From f62e2baac8957b73f0b910d61549087b40f0761a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:13:00 +0800
Subject: [PATCH 01/28] Make the BMP Decoder Core can skip the file header
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Make BmpDecoderCore support AlphaMask.
link #687

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs  | 226 +++++++++++++++---
 .../Formats/Bmp/BmpDecoderOptions.cs          |  24 ++
 2 files changed, 211 insertions(+), 39 deletions(-)

diff --git a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
index bed489752..9bea6867a 100644
--- a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
@@ -71,7 +71,7 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
     /// <summary>
     /// The file header containing general information.
     /// </summary>
-    private BmpFileHeader fileHeader;
+    private BmpFileHeader? fileHeader;
 
     /// <summary>
     /// Indicates which bitmap file marker was read.
@@ -99,6 +99,15 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
     /// </summary>
     private readonly RleSkippedPixelHandling rleSkippedPixelHandling;
 
+    /// <inheritdoc cref="BmpDecoderOptions.ProcessedAlphaMask"/>
+    private readonly bool processedAlphaMask;
+
+    /// <inheritdoc cref="BmpDecoderOptions.SkipFileHeader"/>
+    private readonly bool skipFileHeader;
+
+    /// <inheritdoc cref="BmpDecoderOptions.IsDoubleHeight"/>
+    private readonly bool isDoubleHeight;
+
     /// <summary>
     /// Initializes a new instance of the <see cref="BmpDecoderCore"/> class.
     /// </summary>
@@ -109,6 +118,9 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
         this.rleSkippedPixelHandling = options.RleSkippedPixelHandling;
         this.configuration = options.GeneralOptions.Configuration;
         this.memoryAllocator = this.configuration.MemoryAllocator;
+        this.processedAlphaMask = options.ProcessedAlphaMask;
+        this.skipFileHeader = options.SkipFileHeader;
+        this.isDoubleHeight = options.IsDoubleHeight;
     }
 
     /// <inheritdoc />
@@ -132,38 +144,44 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
 
             switch (this.infoHeader.Compression)
             {
-                case BmpCompression.RGB:
-                    if (this.infoHeader.BitsPerPixel == 32)
-                    {
-                        if (this.bmpMetadata.InfoHeaderType == BmpInfoHeaderType.WinVersion3)
-                        {
-                            this.ReadRgb32Slow(stream, pixels, this.infoHeader.Width, this.infoHeader.Height, inverted);
-                        }
-                        else
-                        {
-                            this.ReadRgb32Fast(stream, pixels, this.infoHeader.Width, this.infoHeader.Height, inverted);
-                        }
-                    }
-                    else if (this.infoHeader.BitsPerPixel == 24)
-                    {
-                        this.ReadRgb24(stream, pixels, this.infoHeader.Width, this.infoHeader.Height, inverted);
-                    }
-                    else if (this.infoHeader.BitsPerPixel == 16)
-                    {
-                        this.ReadRgb16(stream, pixels, this.infoHeader.Width, this.infoHeader.Height, inverted);
-                    }
-                    else if (this.infoHeader.BitsPerPixel <= 8)
-                    {
-                        this.ReadRgbPalette(
-                            stream,
-                            pixels,
-                            palette,
-                            this.infoHeader.Width,
-                            this.infoHeader.Height,
-                            this.infoHeader.BitsPerPixel,
-                            bytesPerColorMapEntry,
-                            inverted);
-                    }
+                case BmpCompression.RGB when this.infoHeader.BitsPerPixel is 32 && this.bmpMetadata.InfoHeaderType is BmpInfoHeaderType.WinVersion3:
+                    this.ReadRgb32Slow(stream, pixels, this.infoHeader.Width, this.infoHeader.Height, inverted);
+
+                    break;
+                case BmpCompression.RGB when this.infoHeader.BitsPerPixel is 32:
+                    this.ReadRgb32Fast(stream, pixels, this.infoHeader.Width, this.infoHeader.Height, inverted);
+
+                    break;
+                case BmpCompression.RGB when this.infoHeader.BitsPerPixel is 24:
+                    this.ReadRgb24(stream, pixels, this.infoHeader.Width, this.infoHeader.Height, inverted);
+
+                    break;
+                case BmpCompression.RGB when this.infoHeader.BitsPerPixel is 16:
+                    this.ReadRgb16(stream, pixels, this.infoHeader.Width, this.infoHeader.Height, inverted);
+
+                    break;
+                case BmpCompression.RGB when this.infoHeader.BitsPerPixel is <= 8 && this.processedAlphaMask:
+                    this.ReadRgbPaletteWithAlphaMask(
+                        stream,
+                        pixels,
+                        palette,
+                        this.infoHeader.Width,
+                        this.infoHeader.Height,
+                        this.infoHeader.BitsPerPixel,
+                        bytesPerColorMapEntry,
+                        inverted);
+
+                    break;
+                case BmpCompression.RGB when this.infoHeader.BitsPerPixel is <= 8:
+                    this.ReadRgbPalette(
+                        stream,
+                        pixels,
+                        palette,
+                        this.infoHeader.Width,
+                        this.infoHeader.Height,
+                        this.infoHeader.BitsPerPixel,
+                        bytesPerColorMapEntry,
+                        inverted);
 
                     break;
 
@@ -839,6 +857,108 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
         }
     }
 
+    /// <inheritdoc cref="ReadRgbPalette"/>
+    private void ReadRgbPaletteWithAlphaMask<TPixel>(BufferedReadStream stream, Buffer2D<TPixel> pixels, byte[] colors, int width, int height, int bitsPerPixel, int bytesPerColorMapEntry, bool inverted)
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        // Pixels per byte (bits per pixel).
+        int ppb = 8 / bitsPerPixel;
+
+        int arrayWidth = (width + ppb - 1) / ppb;
+
+        // Bit mask
+        int mask = 0xFF >> (8 - bitsPerPixel);
+
+        // Rows are aligned on 4 byte boundaries.
+        int padding = arrayWidth % 4;
+        if (padding != 0)
+        {
+            padding = 4 - padding;
+        }
+
+        Bgra32[,] image = new Bgra32[height, width];
+        using (IMemoryOwner<byte> row = this.memoryAllocator.Allocate<byte>(arrayWidth + padding, AllocationOptions.Clean))
+        {
+            Span<byte> rowSpan = row.GetSpan();
+
+            for (int y = 0; y < height; y++)
+            {
+                int newY = Invert(y, height, inverted);
+                if (stream.Read(rowSpan) == 0)
+                {
+                    BmpThrowHelper.ThrowInvalidImageContentException("Could not read enough data for a pixel row!");
+                }
+
+                int offset = 0;
+
+                for (int x = 0; x < arrayWidth; x++)
+                {
+                    int colOffset = x * ppb;
+                    for (int shift = 0, newX = colOffset; shift < ppb && newX < width; shift++, newX++)
+                    {
+                        int colorIndex = ((rowSpan[offset] >> (8 - bitsPerPixel - (shift * bitsPerPixel))) & mask) * bytesPerColorMapEntry;
+
+                        image[newY, newX].FromBgr24(Unsafe.As<byte, Bgr24>(ref colors[colorIndex]));
+                    }
+
+                    offset++;
+                }
+            }
+        }
+
+        arrayWidth = width / 8;
+        padding = arrayWidth % 4;
+        if (padding != 0)
+        {
+            padding = 4 - padding;
+        }
+
+        for (int y = 0; y < height; y++)
+        {
+            int newY = Invert(y, height, inverted);
+
+            for (int i = 0; i < arrayWidth; i++)
+            {
+                int x = i * 8;
+                int and = stream.ReadByte();
+                if (and is -1)
+                {
+                    throw new EndOfStreamException();
+                }
+
+                for (int j = 0; j < 8; j++)
+                {
+                    SetAlpha(ref image[newY, x + j], and, j);
+                }
+            }
+
+            stream.Skip(padding);
+        }
+
+        for (int y = 0; y < height; y++)
+        {
+            int newY = Invert(y, height, inverted);
+            Span<TPixel> pixelRow = pixels.DangerousGetRowSpan(newY);
+
+            for (int x = 0; x < width; x++)
+            {
+                pixelRow[x].FromBgra32(image[newY, x]);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Set pixel's alpha with alpha mask.
+    /// </summary>
+    /// <param name="pixel">Bgra32 pixel.</param>
+    /// <param name="mask">alpha mask.</param>
+    /// <param name="index">bit index of pixel.</param>
+    private static void SetAlpha(ref Bgra32 pixel, in int mask, in int index)
+    {
+        bool isTransparently = (mask & (0b10000000 >> index)) is not 0;
+        pixel.A = isTransparently ? byte.MinValue : byte.MaxValue;
+    }
+
     /// <summary>
     /// Reads the 16 bit color palette from the stream.
     /// </summary>
@@ -1333,6 +1453,11 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
             this.metadata.VerticalResolution = Math.Round(UnitConverter.InchToMeter(ImageMetadata.DefaultVerticalResolution));
         }
 
+        if (this.isDoubleHeight)
+        {
+            this.infoHeader.Height >>= 1;
+        }
+
         ushort bitsPerPixel = this.infoHeader.BitsPerPixel;
         this.bmpMetadata = this.metadata.GetBmpMetadata();
         this.bmpMetadata.InfoHeaderType = infoHeaderType;
@@ -1362,9 +1487,9 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
                 // The bitmap file header of the first image follows the array header.
                 stream.Read(buffer, 0, BmpFileHeader.Size);
                 this.fileHeader = BmpFileHeader.Parse(buffer);
-                if (this.fileHeader.Type != BmpConstants.TypeMarkers.Bitmap)
+                if (this.fileHeader.Value.Type != BmpConstants.TypeMarkers.Bitmap)
                 {
-                    BmpThrowHelper.ThrowNotSupportedException($"Unsupported bitmap file inside a BitmapArray file. File header bitmap type marker '{this.fileHeader.Type}'.");
+                    BmpThrowHelper.ThrowNotSupportedException($"Unsupported bitmap file inside a BitmapArray file. File header bitmap type marker '{this.fileHeader.Value.Type}'.");
                 }
 
                 break;
@@ -1387,7 +1512,11 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
     [MemberNotNull(nameof(bmpMetadata))]
     private int ReadImageHeaders(BufferedReadStream stream, out bool inverted, out byte[] palette)
     {
-        this.ReadFileHeader(stream);
+        if (!this.skipFileHeader)
+        {
+            this.ReadFileHeader(stream);
+        }
+
         this.ReadInfoHeader(stream);
 
         // see http://www.drdobbs.com/architecture-and-design/the-bmp-file-format-part-1/184409517
@@ -1411,7 +1540,21 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
                 switch (this.fileMarkerType)
                 {
                     case BmpFileMarkerType.Bitmap:
-                        colorMapSizeBytes = this.fileHeader.Offset - BmpFileHeader.Size - this.infoHeader.HeaderSize;
+                        if (this.fileHeader.HasValue)
+                        {
+                            colorMapSizeBytes = this.fileHeader.Value.Offset - BmpFileHeader.Size - this.infoHeader.HeaderSize;
+                        }
+                        else
+                        {
+                            colorMapSizeBytes = this.infoHeader.ClrUsed;
+                            if (colorMapSizeBytes is 0 && this.infoHeader.BitsPerPixel is <= 8)
+                            {
+                                colorMapSizeBytes = ColorNumerics.GetColorCountForBitDepth(this.infoHeader.BitsPerPixel);
+                            }
+
+                            colorMapSizeBytes *= 4;
+                        }
+
                         int colorCountForBitDepth = ColorNumerics.GetColorCountForBitDepth(this.infoHeader.BitsPerPixel);
                         bytesPerColorMapEntry = colorMapSizeBytes / colorCountForBitDepth;
 
@@ -1442,7 +1585,7 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
         {
             // Usually the color palette is 1024 byte (256 colors * 4), but the documentation does not mention a size limit.
             // Make sure, that we will not read pass the bitmap offset (starting position of image data).
-            if (stream.Position > this.fileHeader.Offset - colorMapSizeBytes)
+            if (this.fileHeader.HasValue && stream.Position > this.fileHeader.Value.Offset - colorMapSizeBytes)
             {
                 BmpThrowHelper.ThrowInvalidImageContentException(
                     $"Reading the color map would read beyond the bitmap offset. Either the color map size of '{colorMapSizeBytes}' is invalid or the bitmap offset.");
@@ -1456,7 +1599,12 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
             }
         }
 
-        int skipAmount = this.fileHeader.Offset - (int)stream.Position;
+        int skipAmount = 0;
+        if (this.fileHeader.HasValue)
+        {
+            skipAmount = this.fileHeader.Value.Offset - (int)stream.Position;
+        }
+
         if ((skipAmount + (int)stream.Position) > stream.Length)
         {
             BmpThrowHelper.ThrowInvalidImageContentException("Invalid file header offset found. Offset is greater than the stream length.");
diff --git a/src/ImageSharp/Formats/Bmp/BmpDecoderOptions.cs b/src/ImageSharp/Formats/Bmp/BmpDecoderOptions.cs
index b3387ce80..17d37cab2 100644
--- a/src/ImageSharp/Formats/Bmp/BmpDecoderOptions.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpDecoderOptions.cs
@@ -16,4 +16,28 @@ public sealed class BmpDecoderOptions : ISpecializedDecoderOptions
     /// which can occur during decoding run length encoded bitmaps.
     /// </summary>
     public RleSkippedPixelHandling RleSkippedPixelHandling { get; init; }
+
+    /// <summary>
+    /// Gets a value indicating whether the additional AlphaMask is processed at decoding time.
+    /// </summary>
+    /// <remarks>
+    /// It will be used at IcoDecoder.
+    /// </remarks>
+    internal bool ProcessedAlphaMask { get; init; }
+
+    /// <summary>
+    /// Gets a value indicating whether to skip loading the BMP file header.
+    /// </summary>
+    /// <remarks>
+    /// It will be used at IcoDecoder.
+    /// </remarks>
+    internal bool SkipFileHeader { get; init; }
+
+    /// <summary>
+    /// Gets a value indicating whether the height is double of true height.
+    /// </summary>
+    /// <remarks>
+    /// It will be used at IcoDecoder.
+    /// </remarks>
+    internal bool IsDoubleHeight { get; init; }
 }

From 520ff46baaf9927a734947d167072a40bd5b85a3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:13:02 +0800
Subject: [PATCH 02/28] Append BMP's MIME Type
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 src/ImageSharp/Formats/Bmp/BmpConstants.cs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/ImageSharp/Formats/Bmp/BmpConstants.cs b/src/ImageSharp/Formats/Bmp/BmpConstants.cs
index 5cf0c9732..62edfdfdf 100644
--- a/src/ImageSharp/Formats/Bmp/BmpConstants.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpConstants.cs
@@ -11,7 +11,12 @@ internal static class BmpConstants
     /// <summary>
     /// The list of mimetypes that equate to a bmp.
     /// </summary>
-    public static readonly IEnumerable<string> MimeTypes = new[] { "image/bmp", "image/x-windows-bmp" };
+    public static readonly IEnumerable<string> MimeTypes = new[]
+    {
+        "image/bmp",
+        "image/x-windows-bmp",
+        "image/x-win-bitmap"
+    };
 
     /// <summary>
     /// The list of file extensions that equate to a bmp.

From 11293824e3213133eb6e1e4bcdec8a67fed3cbbc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:13:03 +0800
Subject: [PATCH 03/28] Add UnsafeSetFormatMetadata in ImageFrameMetadata
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 src/ImageSharp/Metadata/ImageFrameMetadata.cs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/ImageSharp/Metadata/ImageFrameMetadata.cs b/src/ImageSharp/Metadata/ImageFrameMetadata.cs
index 1c0330d5d..0567c8916 100644
--- a/src/ImageSharp/Metadata/ImageFrameMetadata.cs
+++ b/src/ImageSharp/Metadata/ImageFrameMetadata.cs
@@ -99,6 +99,11 @@ public sealed class ImageFrameMetadata : IDeepCloneable<ImageFrameMetadata>
         return newMeta;
     }
 
+    internal void UnsafeSetFormatMetadata(
+        IImageFormat key,
+        IDeepCloneable value)
+        => this.formatMetadata[key] = value;
+
     /// <summary>
     /// Gets the metadata value associated with the specified key.
     /// </summary>

From 4832d8f24aaadef2827d46f988be0a77bca5018a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:13:03 +0800
Subject: [PATCH 04/28] Add Icon Support
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Ico Decoder
- Ico Detector
- Ico Detector UnitTest
- Cur Decoder
- Cur Detector
- Cur Detector UnitTest

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 ImageSharp.sln                                |   7 +
 src/ImageSharp/Configuration.cs               |   6 +-
 .../Icon/Cur/CurConfigurationModule.cs        |  19 +++
 .../Formats/Icon/Cur/CurConstants.cs          |  28 ++++
 src/ImageSharp/Formats/Icon/Cur/CurDecoder.cs |  47 ++++++
 .../Formats/Icon/Cur/CurDecoderCore.cs        |  16 +++
 src/ImageSharp/Formats/Icon/Cur/CurFormat.cs  |  37 +++++
 .../Formats/Icon/Cur/CurFrameMetadata.cs      |  52 +++++++
 .../Formats/Icon/Cur/CurMetadata.cs           |  16 +++
 .../Formats/Icon/Cur/MetadataExtensions.cs    |  44 ++++++
 .../Icon/Ico/IcoConfigurationModule.cs        |  19 +++
 .../Formats/Icon/Ico/IcoConstants.cs          |  38 +++++
 src/ImageSharp/Formats/Icon/Ico/IcoDecoder.cs |  47 ++++++
 .../Formats/Icon/Ico/IcoDecoderCore.cs        |  16 +++
 src/ImageSharp/Formats/Icon/Ico/IcoFormat.cs  |  37 +++++
 .../Formats/Icon/Ico/IcoFrameMetadata.cs      |  50 +++++++
 .../Formats/Icon/Ico/IcoMetadata.cs           |  16 +++
 .../Formats/Icon/Ico/MetadataExtensions.cs    |  44 ++++++
 src/ImageSharp/Formats/Icon/IconAssert.cs     |  43 ++++++
 .../Formats/Icon/IconDecoderCore.cs           | 136 ++++++++++++++++++
 src/ImageSharp/Formats/Icon/IconDir.cs        |  26 ++++
 src/ImageSharp/Formats/Icon/IconDirEntry.cs   |  28 ++++
 src/ImageSharp/Formats/Icon/IconFileType.cs   |  20 +++
 .../Formats/Icon/IconFrameCompression.cs      |  25 ++++
 .../Formats/Icon/IconFrameMetadata.cs         | 103 +++++++++++++
 .../Formats/Icon/IconImageFormatDetector.cs   |  33 +++++
 tests/ImageSharp.Tests/ConfigurationTests.cs  |   2 +-
 .../Formats/Icon/Cur/CurDecoderTests.cs       |  23 +++
 .../Formats/Icon/Ico/IcoDecoderTests.cs       |  23 +++
 tests/ImageSharp.Tests/TestImages.cs          |  10 ++
 tests/Images/Input/Icon/aero_arrow.cur        |   3 +
 tests/Images/Input/Icon/flutter.ico           |   3 +
 32 files changed, 1015 insertions(+), 2 deletions(-)
 create mode 100644 src/ImageSharp/Formats/Icon/Cur/CurConfigurationModule.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Cur/CurConstants.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Cur/CurDecoder.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Cur/CurFormat.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Cur/CurMetadata.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Cur/MetadataExtensions.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Ico/IcoConfigurationModule.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Ico/IcoConstants.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Ico/IcoDecoder.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Ico/IcoFormat.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Ico/IcoMetadata.cs
 create mode 100644 src/ImageSharp/Formats/Icon/Ico/MetadataExtensions.cs
 create mode 100644 src/ImageSharp/Formats/Icon/IconAssert.cs
 create mode 100644 src/ImageSharp/Formats/Icon/IconDecoderCore.cs
 create mode 100644 src/ImageSharp/Formats/Icon/IconDir.cs
 create mode 100644 src/ImageSharp/Formats/Icon/IconDirEntry.cs
 create mode 100644 src/ImageSharp/Formats/Icon/IconFileType.cs
 create mode 100644 src/ImageSharp/Formats/Icon/IconFrameCompression.cs
 create mode 100644 src/ImageSharp/Formats/Icon/IconFrameMetadata.cs
 create mode 100644 src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
 create mode 100644 tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
 create mode 100644 tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
 create mode 100644 tests/Images/Input/Icon/aero_arrow.cur
 create mode 100644 tests/Images/Input/Icon/flutter.ico

diff --git a/ImageSharp.sln b/ImageSharp.sln
index 162de8416..7ccd92c07 100644
--- a/ImageSharp.sln
+++ b/ImageSharp.sln
@@ -661,6 +661,12 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Qoi", "Qoi", "{E801B508-493
 		tests\Images\Input\Qoi\wikipedia_008.qoi = tests\Images\Input\Qoi\wikipedia_008.qoi
 	EndProjectSection
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Icon", "Icon", "{95E45DDE-A67D-48AD-BBA8-5FAA151B860D}"
+	ProjectSection(SolutionItems) = preProject
+		tests\Images\Input\Icon\aero_arrow.cur = tests\Images\Input\Icon\aero_arrow.cur
+		tests\Images\Input\Icon\flutter.ico = tests\Images\Input\Icon\flutter.ico
+	EndProjectSection
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -714,6 +720,7 @@ Global
 		{670DD46C-82E9-499A-B2D2-00A802ED0141} = {E1C42A6F-913B-4A7B-B1A8-2BB62843B254}
 		{5DFC394F-136F-4B76-9BCA-3BA786515EFC} = {9DA226A1-8656-49A8-A58A-A8B5C081AD66}
 		{E801B508-4935-41CD-BA85-CF11BFF55A45} = {9DA226A1-8656-49A8-A58A-A8B5C081AD66}
+		{95E45DDE-A67D-48AD-BBA8-5FAA151B860D} = {9DA226A1-8656-49A8-A58A-A8B5C081AD66}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {5F8B9D1F-CD8B-4CC5-8216-D531E25BD795}
diff --git a/src/ImageSharp/Configuration.cs b/src/ImageSharp/Configuration.cs
index 1ca5d0a46..d6cfd480d 100644
--- a/src/ImageSharp/Configuration.cs
+++ b/src/ImageSharp/Configuration.cs
@@ -5,6 +5,8 @@ using System.Collections.Concurrent;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Gif;
+using SixLabors.ImageSharp.Formats.Icon.Cur;
+using SixLabors.ImageSharp.Formats.Icon.Ico;
 using SixLabors.ImageSharp.Formats.Jpeg;
 using SixLabors.ImageSharp.Formats.Pbm;
 using SixLabors.ImageSharp.Formats.Png;
@@ -222,5 +224,7 @@ public sealed class Configuration
             new TgaConfigurationModule(),
             new TiffConfigurationModule(),
             new WebpConfigurationModule(),
-            new QoiConfigurationModule());
+            new QoiConfigurationModule(),
+            new IcoConfigurationModule(),
+            new CurConfigurationModule());
 }
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurConfigurationModule.cs b/src/ImageSharp/Formats/Icon/Cur/CurConfigurationModule.cs
new file mode 100644
index 000000000..c975bc609
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Cur/CurConfigurationModule.cs
@@ -0,0 +1,19 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+
+/// <summary>
+/// Registers the image encoders, decoders and mime type detectors for the Ico format.
+/// </summary>
+public sealed class CurConfigurationModule : IImageFormatConfigurationModule
+{
+    /// <inheritdoc/>
+    public void Configure(Configuration configuration)
+    {
+        // TODO: CurEncoder
+        // configuration.ImageFormatsManager.SetEncoder(CurFormat.Instance, new CurEncoder());
+        configuration.ImageFormatsManager.SetDecoder(CurFormat.Instance, CurDecoder.Instance);
+        configuration.ImageFormatsManager.AddImageFormatDetector(new IconImageFormatDetector());
+    }
+}
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurConstants.cs b/src/ImageSharp/Formats/Icon/Cur/CurConstants.cs
new file mode 100644
index 000000000..701b40cf4
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Cur/CurConstants.cs
@@ -0,0 +1,28 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+
+/// <summary>
+/// Defines constants relating to ICOs
+/// </summary>
+internal static class CurConstants
+{
+    /// <summary>
+    /// The list of mimetypes that equate to a ico.
+    /// </summary>
+    /// <remarks>
+    /// See <see href="https://en.wikipedia.org/wiki/ICO_(file_format)#MIME_type"/>
+    /// </remarks>
+    public static readonly IEnumerable<string> MimeTypes = new[]
+    {
+        "application/octet-stream",
+    };
+
+    /// <summary>
+    /// The list of file extensions that equate to a ico.
+    /// </summary>
+    public static readonly IEnumerable<string> FileExtensions = new[] { "cur" };
+
+    public const uint FileHeader = 0x00_02_00_00;
+}
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurDecoder.cs b/src/ImageSharp/Formats/Icon/Cur/CurDecoder.cs
new file mode 100644
index 000000000..ceefdcaba
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Cur/CurDecoder.cs
@@ -0,0 +1,47 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+
+/// <summary>
+/// Decoder for generating an image out of a ico encoded stream.
+/// </summary>
+public sealed class CurDecoder : ImageDecoder
+{
+    private CurDecoder()
+    {
+    }
+
+    /// <summary>
+    /// Gets the shared instance.
+    /// </summary>
+    public static CurDecoder Instance { get; } = new();
+
+    /// <inheritdoc/>
+    protected override Image<TPixel> Decode<TPixel>(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+    {
+        Guard.NotNull(options, nameof(options));
+        Guard.NotNull(stream, nameof(stream));
+
+        Image<TPixel> image = new CurDecoderCore(options).Decode<TPixel>(options.Configuration, stream, cancellationToken);
+
+        ScaleToTargetSize(options, image);
+
+        return image;
+    }
+
+    /// <inheritdoc/>
+    protected override Image Decode(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+            => this.Decode<Rgba32>(options, stream, cancellationToken);
+
+    /// <inheritdoc/>
+    protected override ImageInfo Identify(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+    {
+        Guard.NotNull(options, nameof(options));
+        Guard.NotNull(stream, nameof(stream));
+
+        return new CurDecoderCore(options).Identify(options.Configuration, stream, cancellationToken);
+    }
+}
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs b/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
new file mode 100644
index 000000000..8b08f127d
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
@@ -0,0 +1,16 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Metadata;
+
+namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+
+internal sealed class CurDecoderCore : IconDecoderCore
+{
+    public CurDecoderCore(DecoderOptions options)
+        : base(options)
+    {
+    }
+
+    protected override IconFrameMetadata GetFrameMetadata(ImageFrameMetadata metadata) => metadata.GetCurMetadata();
+}
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurFormat.cs b/src/ImageSharp/Formats/Icon/Cur/CurFormat.cs
new file mode 100644
index 000000000..1e5758bc4
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Cur/CurFormat.cs
@@ -0,0 +1,37 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+
+/// <summary>
+/// Registers the image encoders, decoders and mime type detectors for the ICO format.
+/// </summary>
+public sealed class CurFormat : IImageFormat<CurMetadata, CurFrameMetadata>
+{
+    private CurFormat()
+    {
+    }
+
+    /// <summary>
+    /// Gets the shared instance.
+    /// </summary>
+    public static CurFormat Instance { get; } = new();
+
+    /// <inheritdoc/>
+    public string Name => "ICO";
+
+    /// <inheritdoc/>
+    public string DefaultMimeType => CurConstants.MimeTypes.First();
+
+    /// <inheritdoc/>
+    public IEnumerable<string> MimeTypes => CurConstants.MimeTypes;
+
+    /// <inheritdoc/>
+    public IEnumerable<string> FileExtensions => CurConstants.FileExtensions;
+
+    /// <inheritdoc/>
+    public CurMetadata CreateDefaultFormatMetadata() => new();
+
+    /// <inheritdoc/>
+    public CurFrameMetadata CreateDefaultFormatFrameMetadata() => new();
+}
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs b/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
new file mode 100644
index 000000000..c94afdd3a
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
@@ -0,0 +1,52 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+
+/// <summary>
+/// IcoFrameMetadata
+/// </summary>
+public class CurFrameMetadata : IconFrameMetadata, IDeepCloneable<CurFrameMetadata>, IDeepCloneable
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="CurFrameMetadata"/> class.
+    /// </summary>
+    public CurFrameMetadata()
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="CurFrameMetadata"/> class.
+    /// </summary>
+    /// <param name="metadata">metadata</param>
+    public CurFrameMetadata(IconFrameMetadata metadata)
+        : base(metadata)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="CurFrameMetadata"/> class.
+    /// </summary>
+    /// <param name="width">width</param>
+    /// <param name="height">height</param>
+    /// <param name="colorCount">colorCount</param>
+    /// <param name="field1">field1</param>
+    /// <param name="field2">field2</param>
+    public CurFrameMetadata(byte width, byte height, byte colorCount, ushort field1, ushort field2)
+        : base(width, height, colorCount, field1, field2)
+    {
+    }
+
+    /// <summary>
+    /// Gets or sets Specifies the horizontal coordinates of the hotspot in number of pixels from the left.
+    /// </summary>
+    public ushort HotspotX { get => this.Field1; set => this.Field1 = value; }
+
+    /// <summary>
+    /// Gets or sets Specifies the vertical coordinates of the hotspot in number of pixels from the top.
+    /// </summary>
+    public ushort HotspotY { get => this.Field2; set => this.Field2 = value; }
+
+    /// <inheritdoc/>
+    public override CurFrameMetadata DeepClone() => new(this);
+}
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurMetadata.cs b/src/ImageSharp/Formats/Icon/Cur/CurMetadata.cs
new file mode 100644
index 000000000..ed3c322b4
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Cur/CurMetadata.cs
@@ -0,0 +1,16 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+
+/// <summary>
+/// Provides Ico specific metadata information for the image.
+/// </summary>
+public class CurMetadata : IDeepCloneable<CurMetadata>, IDeepCloneable
+{
+    /// <inheritdoc/>
+    public CurMetadata DeepClone() => new();
+
+    /// <inheritdoc/>
+    IDeepCloneable IDeepCloneable.DeepClone() => this.DeepClone();
+}
diff --git a/src/ImageSharp/Formats/Icon/Cur/MetadataExtensions.cs b/src/ImageSharp/Formats/Icon/Cur/MetadataExtensions.cs
new file mode 100644
index 000000000..400ece648
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Cur/MetadataExtensions.cs
@@ -0,0 +1,44 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Diagnostics.CodeAnalysis;
+using SixLabors.ImageSharp.Metadata;
+
+namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+
+/// <summary>
+/// Extension methods for the <see cref="ImageMetadata"/> type.
+/// </summary>
+public static class MetadataExtensions
+{
+    /// <summary>
+    /// Gets the Icon format specific metadata for the image.
+    /// </summary>
+    /// <param name="source">The metadata this method extends.</param>
+    /// <returns>The <see cref="CurMetadata"/>.</returns>
+    public static CurMetadata GetCurMetadata(this ImageMetadata source)
+        => source.GetFormatMetadata(CurFormat.Instance);
+
+    /// <summary>
+    /// Gets the Icon format specific metadata for the image frame.
+    /// </summary>
+    /// <param name="source">The metadata this method extends.</param>
+    /// <returns>The <see cref="CurFrameMetadata"/>.</returns>
+    public static CurFrameMetadata GetCurMetadata(this ImageFrameMetadata source)
+        => source.GetFormatMetadata(CurFormat.Instance);
+
+    /// <summary>
+    /// Gets the Icon format specific metadata for the image frame.
+    /// </summary>
+    /// <param name="source">The metadata this method extends.</param>
+    /// <param name="metadata">
+    /// When this method returns, contains the metadata associated with the specified frame,
+    /// if found; otherwise, the default value for the type of the metadata parameter.
+    /// This parameter is passed uninitialized.
+    /// </param>
+    /// <returns>
+    /// <see langword="true"/> if the Icon frame metadata exists; otherwise, <see langword="false"/>.
+    /// </returns>
+    public static bool TryGetCurMetadata(this ImageFrameMetadata source, [NotNullWhen(true)] out CurFrameMetadata? metadata)
+        => source.TryGetFormatMetadata(CurFormat.Instance, out metadata);
+}
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoConfigurationModule.cs b/src/ImageSharp/Formats/Icon/Ico/IcoConfigurationModule.cs
new file mode 100644
index 000000000..7074189c7
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoConfigurationModule.cs
@@ -0,0 +1,19 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+
+/// <summary>
+/// Registers the image encoders, decoders and mime type detectors for the Ico format.
+/// </summary>
+public sealed class IcoConfigurationModule : IImageFormatConfigurationModule
+{
+    /// <inheritdoc/>
+    public void Configure(Configuration configuration)
+    {
+        // TODO: IcoEncoder
+        // configuration.ImageFormatsManager.SetEncoder(IcoFormat.Instance, new IcoEncoder());
+        configuration.ImageFormatsManager.SetDecoder(IcoFormat.Instance, IcoDecoder.Instance);
+        configuration.ImageFormatsManager.AddImageFormatDetector(new IconImageFormatDetector());
+    }
+}
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoConstants.cs b/src/ImageSharp/Formats/Icon/Ico/IcoConstants.cs
new file mode 100644
index 000000000..345711705
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoConstants.cs
@@ -0,0 +1,38 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+
+/// <summary>
+/// Defines constants relating to ICOs
+/// </summary>
+internal static class IcoConstants
+{
+    /// <summary>
+    /// The list of mimetypes that equate to a ico.
+    /// </summary>
+    /// <remarks>
+    /// See <see href="https://en.wikipedia.org/wiki/ICO_(file_format)#MIME_type"/>
+    /// </remarks>
+    public static readonly IEnumerable<string> MimeTypes = new[]
+    {
+        // IANA-registered
+        "image/vnd.microsoft.icon",
+
+        // ICO & CUR types used by Windows
+        "image/x-icon",
+
+        // Erroneous types but have been used
+        "image/ico",
+        "image/icon",
+        "text/ico",
+        "application/ico",
+    };
+
+    /// <summary>
+    /// The list of file extensions that equate to a ico.
+    /// </summary>
+    public static readonly IEnumerable<string> FileExtensions = new[] { "ico" };
+
+    public const uint FileHeader = 0x00_01_00_00;
+}
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoDecoder.cs b/src/ImageSharp/Formats/Icon/Ico/IcoDecoder.cs
new file mode 100644
index 000000000..5d6137920
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoDecoder.cs
@@ -0,0 +1,47 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+
+/// <summary>
+/// Decoder for generating an image out of a ico encoded stream.
+/// </summary>
+public sealed class IcoDecoder : ImageDecoder
+{
+    private IcoDecoder()
+    {
+    }
+
+    /// <summary>
+    /// Gets the shared instance.
+    /// </summary>
+    public static IcoDecoder Instance { get; } = new();
+
+    /// <inheritdoc/>
+    protected override Image<TPixel> Decode<TPixel>(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+    {
+        Guard.NotNull(options, nameof(options));
+        Guard.NotNull(stream, nameof(stream));
+
+        Image<TPixel> image = new IcoDecoderCore(options).Decode<TPixel>(options.Configuration, stream, cancellationToken);
+
+        ScaleToTargetSize(options, image);
+
+        return image;
+    }
+
+    /// <inheritdoc/>
+    protected override Image Decode(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+            => this.Decode<Rgba32>(options, stream, cancellationToken);
+
+    /// <inheritdoc/>
+    protected override ImageInfo Identify(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+    {
+        Guard.NotNull(options, nameof(options));
+        Guard.NotNull(stream, nameof(stream));
+
+        return new IcoDecoderCore(options).Identify(options.Configuration, stream, cancellationToken);
+    }
+}
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs b/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
new file mode 100644
index 000000000..0782c2128
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
@@ -0,0 +1,16 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Metadata;
+
+namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+
+internal sealed class IcoDecoderCore : IconDecoderCore
+{
+    public IcoDecoderCore(DecoderOptions options)
+        : base(options)
+    {
+    }
+
+    protected override IconFrameMetadata GetFrameMetadata(ImageFrameMetadata metadata) => metadata.GetIcoMetadata();
+}
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoFormat.cs b/src/ImageSharp/Formats/Icon/Ico/IcoFormat.cs
new file mode 100644
index 000000000..27b0525bf
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoFormat.cs
@@ -0,0 +1,37 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+
+/// <summary>
+/// Registers the image encoders, decoders and mime type detectors for the ICO format.
+/// </summary>
+public sealed class IcoFormat : IImageFormat<IcoMetadata, IcoFrameMetadata>
+{
+    private IcoFormat()
+    {
+    }
+
+    /// <summary>
+    /// Gets the shared instance.
+    /// </summary>
+    public static IcoFormat Instance { get; } = new();
+
+    /// <inheritdoc/>
+    public string Name => "ICO";
+
+    /// <inheritdoc/>
+    public string DefaultMimeType => IcoConstants.MimeTypes.First();
+
+    /// <inheritdoc/>
+    public IEnumerable<string> MimeTypes => IcoConstants.MimeTypes;
+
+    /// <inheritdoc/>
+    public IEnumerable<string> FileExtensions => IcoConstants.FileExtensions;
+
+    /// <inheritdoc/>
+    public IcoMetadata CreateDefaultFormatMetadata() => new();
+
+    /// <inheritdoc/>
+    public IcoFrameMetadata CreateDefaultFormatFrameMetadata() => new();
+}
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs b/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
new file mode 100644
index 000000000..7c903facd
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
@@ -0,0 +1,50 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+
+/// <summary>
+/// IcoFrameMetadata
+/// </summary>
+public class IcoFrameMetadata : IconFrameMetadata, IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="IcoFrameMetadata"/> class.
+    /// </summary>
+    public IcoFrameMetadata()
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="IcoFrameMetadata"/> class.
+    /// </summary>
+    /// <param name="metadata">metadata</param>
+    public IcoFrameMetadata(IconFrameMetadata metadata)
+        : base(metadata)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="IcoFrameMetadata"/> class.
+    /// </summary>
+    /// <param name="width">width</param>
+    /// <param name="height">height</param>
+    /// <param name="colorCount">colorCount</param>
+    /// <param name="field1">field1</param>
+    /// <param name="field2">field2</param>
+    public IcoFrameMetadata(byte width, byte height, byte colorCount, ushort field1, ushort field2)
+        : base(width, height, colorCount, field1, field2)
+    {
+    }
+
+    /// <summary>
+    /// Gets or sets Specifies bits per pixel.
+    /// </summary>
+    /// <remarks>
+    /// It may used by Encoder.
+    /// </remarks>
+    public ushort BitCount { get => this.Field2; set => this.Field2 = value; }
+
+    /// <inheritdoc/>
+    public override IcoFrameMetadata DeepClone() => new(this);
+}
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoMetadata.cs b/src/ImageSharp/Formats/Icon/Ico/IcoMetadata.cs
new file mode 100644
index 000000000..b227d0bd6
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoMetadata.cs
@@ -0,0 +1,16 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+
+/// <summary>
+/// Provides Ico specific metadata information for the image.
+/// </summary>
+public class IcoMetadata : IDeepCloneable<IcoMetadata>, IDeepCloneable
+{
+    /// <inheritdoc/>
+    public IcoMetadata DeepClone() => new();
+
+    /// <inheritdoc/>
+    IDeepCloneable IDeepCloneable.DeepClone() => this.DeepClone();
+}
diff --git a/src/ImageSharp/Formats/Icon/Ico/MetadataExtensions.cs b/src/ImageSharp/Formats/Icon/Ico/MetadataExtensions.cs
new file mode 100644
index 000000000..fb5b4afe7
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/Ico/MetadataExtensions.cs
@@ -0,0 +1,44 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Diagnostics.CodeAnalysis;
+using SixLabors.ImageSharp.Metadata;
+
+namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+
+/// <summary>
+/// Extension methods for the <see cref="ImageMetadata"/> type.
+/// </summary>
+public static class MetadataExtensions
+{
+    /// <summary>
+    /// Gets the Ico format specific metadata for the image.
+    /// </summary>
+    /// <param name="source">The metadata this method extends.</param>
+    /// <returns>The <see cref="IcoMetadata"/>.</returns>
+    public static IcoMetadata GetIcoMetadata(this ImageMetadata source)
+        => source.GetFormatMetadata(IcoFormat.Instance);
+
+    /// <summary>
+    /// Gets the Ico format specific metadata for the image frame.
+    /// </summary>
+    /// <param name="source">The metadata this method extends.</param>
+    /// <returns>The <see cref="IcoFrameMetadata"/>.</returns>
+    public static IcoFrameMetadata GetIcoMetadata(this ImageFrameMetadata source)
+        => source.GetFormatMetadata(IcoFormat.Instance);
+
+    /// <summary>
+    /// Gets the Ico format specific metadata for the image frame.
+    /// </summary>
+    /// <param name="source">The metadata this method extends.</param>
+    /// <param name="metadata">
+    /// When this method returns, contains the metadata associated with the specified frame,
+    /// if found; otherwise, the default value for the type of the metadata parameter.
+    /// This parameter is passed uninitialized.
+    /// </param>
+    /// <returns>
+    /// <see langword="true"/> if the Ico frame metadata exists; otherwise, <see langword="false"/>.
+    /// </returns>
+    public static bool TryGetIcoMetadata(this ImageFrameMetadata source, [NotNullWhen(true)] out IcoFrameMetadata? metadata)
+        => source.TryGetFormatMetadata(IcoFormat.Instance, out metadata);
+}
diff --git a/src/ImageSharp/Formats/Icon/IconAssert.cs b/src/ImageSharp/Formats/Icon/IconAssert.cs
new file mode 100644
index 000000000..bcb427c1a
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/IconAssert.cs
@@ -0,0 +1,43 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon;
+
+internal class IconAssert
+{
+    internal static void CanSeek(Stream stream)
+    {
+        if (!stream.CanSeek)
+        {
+            throw new NotSupportedException("This stream cannot support seek");
+        }
+    }
+
+    internal static int EndOfStream(int v, int length)
+    {
+        if (v != length)
+        {
+            throw new EndOfStreamException();
+        }
+
+        return v;
+    }
+
+    internal static long EndOfStream(long v, long length)
+    {
+        if (v != length)
+        {
+            throw new EndOfStreamException();
+        }
+
+        return v;
+    }
+
+    internal static void NotSquare(in Size size)
+    {
+        if (size.Width != size.Height)
+        {
+            throw new FormatException("This image is not square.");
+        }
+    }
+}
diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
new file mode 100644
index 000000000..d9a578ff2
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -0,0 +1,136 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Runtime.InteropServices;
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.IO;
+using SixLabors.ImageSharp.Metadata;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Icon;
+
+internal abstract class IconDecoderCore : IImageDecoderInternals
+{
+    private IconDir fileHeader;
+
+    public IconDecoderCore(DecoderOptions options) => this.Options = options;
+
+    public DecoderOptions Options { get; }
+
+    public Size Dimensions { get; private set; }
+
+    protected IconDir FileHeader { get => this.fileHeader; private set => this.fileHeader = value; }
+
+    protected IconDirEntry[] Entries { get; private set; } = Array.Empty<IconDirEntry>();
+
+    public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken)
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        // Stream may not at 0.
+        long basePosition = stream.Position;
+        this.ReadHeader(stream);
+
+        Span<byte> flag = stackalloc byte[Png.PngConstants.HeaderBytes.Length];
+
+        List<(Image<TPixel> Image, bool IsPng, int Index)> frames = new(this.Entries.Length);
+        for (int i = 0; i < this.Entries.Length; i++)
+        {
+            _ = IconAssert.EndOfStream(stream.Seek(basePosition + this.Entries[i].ImageOffset, SeekOrigin.Begin), basePosition + this.Entries[i].ImageOffset);
+            _ = IconAssert.EndOfStream(stream.Read(flag), Png.PngConstants.HeaderBytes.Length);
+            _ = stream.Seek(-Png.PngConstants.HeaderBytes.Length, SeekOrigin.Current);
+
+            bool isPng = flag.SequenceEqual(Png.PngConstants.HeaderBytes);
+
+            Image<TPixel> img = this.GetDecoder(isPng).Decode<TPixel>(stream, cancellationToken);
+            IconAssert.NotSquare(img.Size);
+            frames.Add((img, isPng, i));
+            if (isPng && img.Size.Width > this.Dimensions.Width)
+            {
+                this.Dimensions = img.Size;
+            }
+        }
+
+        ImageMetadata metadata = new();
+        return new(this.Options.Configuration, metadata, frames.Select(i =>
+        {
+            ImageFrame<TPixel> target = new(this.Options.Configuration, this.Dimensions);
+            ImageFrame<TPixel> source = i.Image.Frames.RootFrameUnsafe;
+            for (int h = 0; h < source.Height; h++)
+            {
+                source.PixelBuffer.DangerousGetRowSpan(h).CopyTo(target.PixelBuffer.DangerousGetRowSpan(h));
+            }
+
+            if (i.IsPng)
+            {
+                target.Metadata.UnsafeSetFormatMetadata(Png.PngFormat.Instance, i.Image.Metadata.GetPngMetadata());
+            }
+            else
+            {
+                target.Metadata.UnsafeSetFormatMetadata(Bmp.BmpFormat.Instance, i.Image.Metadata.GetBmpMetadata());
+            }
+
+            this.GetFrameMetadata(target.Metadata).FromIconDirEntry(this.Entries[i.Index]);
+
+            i.Image.Dispose();
+            return target;
+        }).ToArray());
+    }
+
+    public ImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken)
+    {
+        this.ReadHeader(stream);
+
+        ImageMetadata metadata = new();
+        ImageFrameMetadata[] frames = new ImageFrameMetadata[this.FileHeader.Count];
+        for (int i = 0; i < frames.Length; i++)
+        {
+            frames[i] = new();
+            IconFrameMetadata icoFrameMetadata = this.GetFrameMetadata(frames[i]);
+            icoFrameMetadata.FromIconDirEntry(this.Entries[i]);
+        }
+
+        return new(new(32), new(0), metadata, frames);
+    }
+
+    protected abstract IconFrameMetadata GetFrameMetadata(ImageFrameMetadata metadata);
+
+    protected void ReadHeader(Stream stream)
+    {
+        _ = Read(stream, out this.fileHeader, IconDir.Size);
+        this.Entries = new IconDirEntry[this.FileHeader.Count];
+        for (int i = 0; i < this.Entries.Length; i++)
+        {
+            _ = Read(stream, out this.Entries[i], IconDirEntry.Size);
+        }
+
+        this.Dimensions = new(
+             this.Entries.Max(i => i.Width),
+             this.Entries.Max(i => i.Height));
+    }
+
+    private static int Read<T>(Stream stream, out T data, int size)
+        where T : unmanaged
+    {
+        Span<byte> buffer = stackalloc byte[size];
+        _ = IconAssert.EndOfStream(stream.Read(buffer), size);
+        data = MemoryMarshal.Cast<byte, T>(buffer)[0];
+        return size;
+    }
+
+    private IImageDecoderInternals GetDecoder(bool isPng)
+    {
+        if (isPng)
+        {
+            return new Png.PngDecoderCore(this.Options);
+        }
+        else
+        {
+            return new Bmp.BmpDecoderCore(new()
+            {
+                ProcessedAlphaMask = true,
+                SkipFileHeader = true,
+                IsDoubleHeight = true,
+            });
+        }
+    }
+}
diff --git a/src/ImageSharp/Formats/Icon/IconDir.cs b/src/ImageSharp/Formats/Icon/IconDir.cs
new file mode 100644
index 000000000..f1281a568
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/IconDir.cs
@@ -0,0 +1,26 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Runtime.InteropServices;
+
+namespace SixLabors.ImageSharp.Formats.Icon;
+
+[StructLayout(LayoutKind.Sequential, Pack = 1, Size = Size)]
+internal struct IconDir
+{
+    public const int Size = 3 * sizeof(ushort);
+    public ushort Reserved;
+    public IconFileType Type;
+    public ushort Count;
+
+    public IconDir(IconFileType type)
+        : this(type, 0)
+        => this.Type = type;
+
+    public IconDir(IconFileType type, ushort count)
+    {
+        this.Reserved = 0;
+        this.Type = type;
+        this.Count = count;
+    }
+}
diff --git a/src/ImageSharp/Formats/Icon/IconDirEntry.cs b/src/ImageSharp/Formats/Icon/IconDirEntry.cs
new file mode 100644
index 000000000..43254f89d
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/IconDirEntry.cs
@@ -0,0 +1,28 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Runtime.InteropServices;
+
+namespace SixLabors.ImageSharp.Formats.Icon;
+
+[StructLayout(LayoutKind.Sequential, Pack = 1, Size = Size)]
+internal struct IconDirEntry
+{
+    public const int Size = (4 * sizeof(byte)) + (2 * sizeof(ushort)) + (2 * sizeof(uint));
+
+    public byte Width;
+
+    public byte Height;
+
+    public byte ColorCount;
+
+    public byte Reserved;
+
+    public ushort Planes;
+
+    public ushort BitCount;
+
+    public uint BytesInRes;
+
+    public uint ImageOffset;
+}
diff --git a/src/ImageSharp/Formats/Icon/IconFileType.cs b/src/ImageSharp/Formats/Icon/IconFileType.cs
new file mode 100644
index 000000000..3450698f1
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/IconFileType.cs
@@ -0,0 +1,20 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon;
+
+/// <summary>
+/// Ico file type
+/// </summary>
+internal enum IconFileType : ushort
+{
+    /// <summary>
+    /// ICO file
+    /// </summary>
+    ICO = 1,
+
+    /// <summary>
+    /// CUR file
+    /// </summary>
+    CUR = 2,
+}
diff --git a/src/ImageSharp/Formats/Icon/IconFrameCompression.cs b/src/ImageSharp/Formats/Icon/IconFrameCompression.cs
new file mode 100644
index 000000000..f6509f40c
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/IconFrameCompression.cs
@@ -0,0 +1,25 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon;
+
+/// <summary>
+/// IconFrameCompression
+/// </summary>
+public enum IconFrameCompression
+{
+    /// <summary>
+    /// Unknown
+    /// </summary>
+    Unknown,
+
+    /// <summary>
+    /// Bmp
+    /// </summary>
+    Bmp,
+
+    /// <summary>
+    /// Png
+    /// </summary>
+    Png
+}
diff --git a/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs b/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs
new file mode 100644
index 000000000..17e641c71
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs
@@ -0,0 +1,103 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Icon;
+
+/// <summary>
+/// IconFrameMetadata
+/// </summary>
+public abstract class IconFrameMetadata : IDeepCloneable
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="IconFrameMetadata"/> class.
+    /// </summary>
+    protected IconFrameMetadata()
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="IconFrameMetadata"/> class.
+    /// </summary>
+    /// <param name="width">width</param>
+    /// <param name="height">height</param>
+    /// <param name="colorCount">colorCount</param>
+    /// <param name="field1">field1</param>
+    /// <param name="field2">field2</param>
+    protected IconFrameMetadata(byte width, byte height, byte colorCount, ushort field1, ushort field2)
+    {
+        this.EncodingWidth = width;
+        this.EncodingHeight = height;
+        this.ColorCount = colorCount;
+        this.Field1 = field1;
+        this.Field2 = field2;
+    }
+
+    /// <inheritdoc cref="IconFrameMetadata()"/>
+    protected IconFrameMetadata(IconFrameMetadata metadata)
+    {
+        this.EncodingWidth = metadata.EncodingWidth;
+        this.EncodingHeight = metadata.EncodingHeight;
+        this.ColorCount = metadata.ColorCount;
+        this.Field1 = metadata.Field1;
+        this.Field2 = metadata.Field2;
+    }
+
+    /// <summary>
+    /// Gets or sets icoFrameCompression.
+    /// </summary>
+    public IconFrameCompression Compression { get; protected set; }
+
+    /// <summary>
+    /// Gets or sets ColorCount field. <br />
+    /// Specifies number of colors in the color palette. Should be 0 if the image does not use a color palette.
+    /// </summary>
+    // TODO: BmpMetadata does not supported palette yet.
+    public byte ColorCount { get; set; }
+
+    /// <summary>
+    /// Gets or sets Planes field. <br />
+    /// In ICO format: Specifies color planes. Should be 0 or 1. <br />
+    /// In CUR format: Specifies the horizontal coordinates of the hotspot in number of pixels from the left.
+    /// </summary>
+    protected ushort Field1 { get; set; }
+
+    /// <summary>
+    /// Gets or sets BitCount field. <br />
+    /// In ICO format: Specifies bits per pixel. <br />
+    /// In CUR format: Specifies the vertical coordinates of the hotspot in number of pixels from the top.
+    /// </summary>
+    protected ushort Field2 { get; set; }
+
+    /// <summary>
+    /// Gets or sets Height field. <br />
+    /// Specifies image height in pixels. Can be any number between 0 and 255. Value 0 means image height is 256 pixels.
+    /// </summary>
+    public byte EncodingHeight { get; set; }
+
+    /// <summary>
+    /// Gets or sets Width field. <br />
+    /// Specifies image width in pixels. Can be any number between 0 and 255. Value 0 means image width is 256 pixels.
+    /// </summary>
+    public byte EncodingWidth { get; set; }
+
+    /// <inheritdoc/>
+    public abstract IDeepCloneable DeepClone();
+
+    internal void FromIconDirEntry(in IconDirEntry metadata)
+    {
+        this.EncodingWidth = metadata.Width;
+        this.EncodingHeight = metadata.Height;
+        this.ColorCount = metadata.ColorCount;
+        this.Field1 = metadata.Planes;
+        this.Field2 = metadata.BitCount;
+    }
+
+    internal IconDirEntry ToIconDirEntry() => new()
+    {
+        Width = this.EncodingWidth,
+        Height = this.EncodingHeight,
+        ColorCount = this.ColorCount,
+        Planes = this.Field1,
+        BitCount = this.Field2,
+    };
+}
diff --git a/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs b/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
new file mode 100644
index 000000000..aff8dfe0a
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
@@ -0,0 +1,33 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.InteropServices;
+
+namespace SixLabors.ImageSharp.Formats.Icon;
+
+/// <summary>
+/// Detects ico file headers.
+/// </summary>
+public class IconImageFormatDetector : IImageFormatDetector
+{
+    /// <inheritdoc/>
+    public int HeaderSize { get; } = 4;
+
+    /// <inheritdoc/>
+    public bool TryDetectFormat(ReadOnlySpan<byte> header, [NotNullWhen(true)] out IImageFormat? format)
+    {
+        switch (MemoryMarshal.Cast<byte, uint>(header)[0])
+        {
+            case Ico.IcoConstants.FileHeader:
+                format = Ico.IcoFormat.Instance;
+                return true;
+            case Cur.CurConstants.FileHeader:
+                format = Cur.CurFormat.Instance;
+                return true;
+            default:
+                format = default;
+                return false;
+        }
+    }
+}
diff --git a/tests/ImageSharp.Tests/ConfigurationTests.cs b/tests/ImageSharp.Tests/ConfigurationTests.cs
index c5d61726c..c8e6cd265 100644
--- a/tests/ImageSharp.Tests/ConfigurationTests.cs
+++ b/tests/ImageSharp.Tests/ConfigurationTests.cs
@@ -20,7 +20,7 @@ public class ConfigurationTests
 
     public Configuration DefaultConfiguration { get; }
 
-    private readonly int expectedDefaultConfigurationCount = 9;
+    private readonly int expectedDefaultConfigurationCount = 11;
 
     public ConfigurationTests()
     {
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
new file mode 100644
index 000000000..c3c9ad1c4
--- /dev/null
+++ b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
@@ -0,0 +1,23 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Formats.Icon.Cur;
+using SixLabors.ImageSharp.Formats.Tiff;
+using SixLabors.ImageSharp.PixelFormats;
+using static SixLabors.ImageSharp.Tests.TestImages.Cur;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Icon.Cur;
+
+[Trait("Format", "Cur")]
+[ValidateDisposedMemoryAllocations]
+public class CurDecoderTests
+{
+    [Theory]
+    [WithFile(WindowsMouse, PixelTypes.Rgba32)]
+    public void CurDecoder_Decode(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(CurDecoder.Instance);
+
+        image.DebugSave(provider, extension: "tiff", encoder: new TiffEncoder());
+    }
+}
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
new file mode 100644
index 000000000..6e7b35111
--- /dev/null
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
@@ -0,0 +1,23 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Formats.Icon.Ico;
+using SixLabors.ImageSharp.Formats.Tiff;
+using SixLabors.ImageSharp.PixelFormats;
+using static SixLabors.ImageSharp.Tests.TestImages.Ico;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Icon.Ico;
+
+[Trait("Format", "Icon")]
+[ValidateDisposedMemoryAllocations]
+public class IcoDecoderTests
+{
+    [Theory]
+    [WithFile(Flutter, PixelTypes.Rgba32)]
+    public void IcoDecoder_Decode(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSave(provider, extension: "tiff", encoder: new TiffEncoder());
+    }
+}
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index a45931e29..c64bf2b34 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -1121,4 +1121,14 @@ public static class TestImages
         public const string TestCardRGBA = "Qoi/testcard_rgba.qoi";
         public const string Wikipedia008 = "Qoi/wikipedia_008.qoi";
     }
+
+    public static class Ico
+    {
+        public const string Flutter = "Icon/flutter.ico";
+    }
+
+    public static class Cur
+    {
+        public const string WindowsMouse = "Icon/aero_arrow.cur";
+    }
 }
diff --git a/tests/Images/Input/Icon/aero_arrow.cur b/tests/Images/Input/Icon/aero_arrow.cur
new file mode 100644
index 000000000..82cbbd33e
--- /dev/null
+++ b/tests/Images/Input/Icon/aero_arrow.cur
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:06678bbf954f0bece61062633dc63a52a34a6f3c27ac7108f28c0f0d26bb22a7
+size 136606
diff --git a/tests/Images/Input/Icon/flutter.ico b/tests/Images/Input/Icon/flutter.ico
new file mode 100644
index 000000000..4001f1426
--- /dev/null
+++ b/tests/Images/Input/Icon/flutter.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c098d3fc85cacff98b8e69811b48e9f0d852fcee278132d794411d978869cbf8
+size 33772

From ffde9a9380698c19b693847ad24f7789ccae9207 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 14 Dec 2023 14:13:53 +0800
Subject: [PATCH 05/28] Refactor decoder and add notes

---
 src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs  |   4 +-
 .../Formats/Bmp/BmpDecoderOptions.cs          |  12 +-
 .../Formats/Icon/Cur/CurDecoderCore.cs        |   2 +
 .../Formats/Icon/Cur/CurFrameMetadata.cs      |   2 +-
 .../Formats/Icon/Ico/IcoDecoderCore.cs        |   2 +
 .../Formats/Icon/Ico/IcoFrameMetadata.cs      |   8 +-
 src/ImageSharp/Formats/Icon/IconAssert.cs     |   8 --
 .../Formats/Icon/IconDecoderCore.cs           | 107 ++++++++++++------
 .../Formats/Icon/IconFrameCompression.cs      |   5 -
 .../Formats/Icon/IconFrameMetadata.cs         |   1 +
 src/ImageSharp/Metadata/ImageFrameMetadata.cs |   6 +-
 src/ImageSharp/Metadata/ImageMetadata.cs      |   3 +
 .../Formats/Icon/Cur/CurDecoderTests.cs       |   7 +-
 .../Formats/Icon/Ico/IcoDecoderTests.cs       |   5 +-
 14 files changed, 106 insertions(+), 66 deletions(-)

diff --git a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
index 9bea6867a..568eea00a 100644
--- a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
@@ -105,7 +105,7 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
     /// <inheritdoc cref="BmpDecoderOptions.SkipFileHeader"/>
     private readonly bool skipFileHeader;
 
-    /// <inheritdoc cref="BmpDecoderOptions.IsDoubleHeight"/>
+    /// <inheritdoc cref="BmpDecoderOptions.UseDoubleHeight"/>
     private readonly bool isDoubleHeight;
 
     /// <summary>
@@ -120,7 +120,7 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
         this.memoryAllocator = this.configuration.MemoryAllocator;
         this.processedAlphaMask = options.ProcessedAlphaMask;
         this.skipFileHeader = options.SkipFileHeader;
-        this.isDoubleHeight = options.IsDoubleHeight;
+        this.isDoubleHeight = options.UseDoubleHeight;
     }
 
     /// <inheritdoc />
diff --git a/src/ImageSharp/Formats/Bmp/BmpDecoderOptions.cs b/src/ImageSharp/Formats/Bmp/BmpDecoderOptions.cs
index 17d37cab2..158a9d479 100644
--- a/src/ImageSharp/Formats/Bmp/BmpDecoderOptions.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpDecoderOptions.cs
@@ -18,10 +18,10 @@ public sealed class BmpDecoderOptions : ISpecializedDecoderOptions
     public RleSkippedPixelHandling RleSkippedPixelHandling { get; init; }
 
     /// <summary>
-    /// Gets a value indicating whether the additional AlphaMask is processed at decoding time.
+    /// Gets a value indicating whether the additional alpha mask is processed at decoding time.
     /// </summary>
     /// <remarks>
-    /// It will be used at IcoDecoder.
+    /// Used by the icon decoder.
     /// </remarks>
     internal bool ProcessedAlphaMask { get; init; }
 
@@ -29,15 +29,15 @@ public sealed class BmpDecoderOptions : ISpecializedDecoderOptions
     /// Gets a value indicating whether to skip loading the BMP file header.
     /// </summary>
     /// <remarks>
-    /// It will be used at IcoDecoder.
+    /// Used by the icon decoder.
     /// </remarks>
     internal bool SkipFileHeader { get; init; }
 
     /// <summary>
-    /// Gets a value indicating whether the height is double of true height.
+    /// Gets a value indicating whether to treat the height as double of true height.
     /// </summary>
     /// <remarks>
-    /// It will be used at IcoDecoder.
+    /// Used by the icon decoder.
     /// </remarks>
-    internal bool IsDoubleHeight { get; init; }
+    internal bool UseDoubleHeight { get; init; }
 }
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs b/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
index 8b08f127d..44fcc8fcc 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
@@ -3,6 +3,8 @@
 
 using SixLabors.ImageSharp.Metadata;
 
+// TODO: flatten namespace.
+// namespace SixLabors.ImageSharp.Formats.Cur;
 namespace SixLabors.ImageSharp.Formats.Icon.Cur;
 
 internal sealed class CurDecoderCore : IconDecoderCore
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs b/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
index c94afdd3a..60ced16ea 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
@@ -4,7 +4,7 @@
 namespace SixLabors.ImageSharp.Formats.Icon.Cur;
 
 /// <summary>
-/// IcoFrameMetadata
+/// IcoFrameMetadata. TODO: Remove base class and merge into this class.
 /// </summary>
 public class CurFrameMetadata : IconFrameMetadata, IDeepCloneable<CurFrameMetadata>, IDeepCloneable
 {
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs b/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
index 0782c2128..677a9c07a 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
@@ -3,6 +3,8 @@
 
 using SixLabors.ImageSharp.Metadata;
 
+// TODO: flatten namespace.
+// namespace SixLabors.ImageSharp.Formats.Ico;
 namespace SixLabors.ImageSharp.Formats.Icon.Ico;
 
 internal sealed class IcoDecoderCore : IconDecoderCore
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs b/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
index 7c903facd..4f557715d 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
@@ -4,7 +4,7 @@
 namespace SixLabors.ImageSharp.Formats.Icon.Ico;
 
 /// <summary>
-/// IcoFrameMetadata
+/// IcoFrameMetadata. TODO: Remove base class and merge into this class.
 /// </summary>
 public class IcoFrameMetadata : IconFrameMetadata, IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
 {
@@ -38,11 +38,9 @@ public class IcoFrameMetadata : IconFrameMetadata, IDeepCloneable<IcoFrameMetada
     }
 
     /// <summary>
-    /// Gets or sets Specifies bits per pixel.
+    /// Gets or sets the bits per pixel.
+    /// TODO: This needs to be constrained and calculated using the metadata returned from the png/bmp.
     /// </summary>
-    /// <remarks>
-    /// It may used by Encoder.
-    /// </remarks>
     public ushort BitCount { get => this.Field2; set => this.Field2 = value; }
 
     /// <inheritdoc/>
diff --git a/src/ImageSharp/Formats/Icon/IconAssert.cs b/src/ImageSharp/Formats/Icon/IconAssert.cs
index bcb427c1a..04a9527b9 100644
--- a/src/ImageSharp/Formats/Icon/IconAssert.cs
+++ b/src/ImageSharp/Formats/Icon/IconAssert.cs
@@ -32,12 +32,4 @@ internal class IconAssert
 
         return v;
     }
-
-    internal static void NotSquare(in Size size)
-    {
-        if (size.Width != size.Height)
-        {
-            throw new FormatException("This image is not square.");
-        }
-    }
 }
diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index d9a578ff2..d7fc25c69 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -2,7 +2,8 @@
 // Licensed under the Six Labors Split License.
 
 using System.Runtime.InteropServices;
-using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.Formats.Bmp;
+using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.IO;
 using SixLabors.ImageSharp.Metadata;
 using SixLabors.ImageSharp.PixelFormats;
@@ -30,50 +31,63 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         long basePosition = stream.Position;
         this.ReadHeader(stream);
 
-        Span<byte> flag = stackalloc byte[Png.PngConstants.HeaderBytes.Length];
+        Span<byte> flag = stackalloc byte[PngConstants.HeaderBytes.Length];
+        Image<TPixel> result = new(this.Dimensions.Width, this.Dimensions.Height);
 
-        List<(Image<TPixel> Image, bool IsPng, int Index)> frames = new(this.Entries.Length);
         for (int i = 0; i < this.Entries.Length; i++)
         {
-            _ = IconAssert.EndOfStream(stream.Seek(basePosition + this.Entries[i].ImageOffset, SeekOrigin.Begin), basePosition + this.Entries[i].ImageOffset);
-            _ = IconAssert.EndOfStream(stream.Read(flag), Png.PngConstants.HeaderBytes.Length);
-            _ = stream.Seek(-Png.PngConstants.HeaderBytes.Length, SeekOrigin.Current);
+            ref IconDirEntry entry = ref this.Entries[i];
 
-            bool isPng = flag.SequenceEqual(Png.PngConstants.HeaderBytes);
+            // If we hit the end of the stream we should break.
+            if (stream.Seek(basePosition + entry.ImageOffset, SeekOrigin.Begin) >= stream.Length)
+            {
+                break;
+            }
 
-            Image<TPixel> img = this.GetDecoder(isPng).Decode<TPixel>(stream, cancellationToken);
-            IconAssert.NotSquare(img.Size);
-            frames.Add((img, isPng, i));
-            if (isPng && img.Size.Width > this.Dimensions.Width)
+            // There should always be enough bytes for this regardless of the entry type.
+            if (stream.Read(flag) != PngConstants.HeaderBytes.Length)
             {
-                this.Dimensions = img.Size;
+                break;
             }
-        }
 
-        ImageMetadata metadata = new();
-        return new(this.Options.Configuration, metadata, frames.Select(i =>
-        {
-            ImageFrame<TPixel> target = new(this.Options.Configuration, this.Dimensions);
-            ImageFrame<TPixel> source = i.Image.Frames.RootFrameUnsafe;
+            // Reset the stream position.
+            stream.Seek(-PngConstants.HeaderBytes.Length, SeekOrigin.Current);
+
+            bool isPng = flag.SequenceEqual(PngConstants.HeaderBytes);
+            using Image<TPixel> temp = this.GetDecoder(isPng).Decode<TPixel>(stream, cancellationToken);
+
+            ImageFrame<TPixel> source = temp.Frames.RootFrameUnsafe;
+            ImageFrame<TPixel> target = i == 0 ? result.Frames.RootFrameUnsafe : result.Frames.CreateFrame();
+
+            // Draw the new frame at position 0,0. We capture the dimensions for cropping during encoding
+            // via the icon entry.
             for (int h = 0; h < source.Height; h++)
             {
                 source.PixelBuffer.DangerousGetRowSpan(h).CopyTo(target.PixelBuffer.DangerousGetRowSpan(h));
             }
 
-            if (i.IsPng)
+            // Copy the format specific metadata to the image.
+            if (isPng)
             {
-                target.Metadata.UnsafeSetFormatMetadata(Png.PngFormat.Instance, i.Image.Metadata.GetPngMetadata());
+                if (i == 0)
+                {
+                    result.Metadata.SetFormatMetadata(PngFormat.Instance, temp.Metadata.GetPngMetadata());
+                }
+
+                target.Metadata.SetFormatMetadata(PngFormat.Instance, target.Metadata.GetPngFrameMetadata());
             }
-            else
+            else if (i == 0)
             {
-                target.Metadata.UnsafeSetFormatMetadata(Bmp.BmpFormat.Instance, i.Image.Metadata.GetBmpMetadata());
+                // Bmp does not contain frame specific metadata.
+                result.Metadata.SetFormatMetadata(BmpFormat.Instance, temp.Metadata.GetBmpMetadata());
             }
 
-            this.GetFrameMetadata(target.Metadata).FromIconDirEntry(this.Entries[i.Index]);
+            // TODO: The inheriting decoder should be responsible for setting the actual data (FromIconDirEntry)
+            // so we can avoid the protected Field1 and Field2 properties and use strong typing.
+            this.GetFrameMetadata(target.Metadata).FromIconDirEntry(entry);
+        }
 
-            i.Image.Dispose();
-            return target;
-        }).ToArray());
+        return result;
     }
 
     public ImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken)
@@ -84,11 +98,14 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         ImageFrameMetadata[] frames = new ImageFrameMetadata[this.FileHeader.Count];
         for (int i = 0; i < frames.Length; i++)
         {
+            // TODO: Use the Identify methods in each decoder to return the
+            // format specific metadata for the image and frame.
             frames[i] = new();
             IconFrameMetadata icoFrameMetadata = this.GetFrameMetadata(frames[i]);
             icoFrameMetadata.FromIconDirEntry(this.Entries[i]);
         }
 
+        // TODO: Use real values from the metadata.
         return new(new(32), new(0), metadata, frames);
     }
 
@@ -96,6 +113,7 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
 
     protected void ReadHeader(Stream stream)
     {
+        // TODO: Check length and throw if the header cannot be read.
         _ = Read(stream, out this.fileHeader, IconDir.Size);
         this.Entries = new IconDirEntry[this.FileHeader.Count];
         for (int i = 0; i < this.Entries.Length; i++)
@@ -103,15 +121,39 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
             _ = Read(stream, out this.Entries[i], IconDirEntry.Size);
         }
 
-        this.Dimensions = new(
-             this.Entries.Max(i => i.Width),
-             this.Entries.Max(i => i.Height));
+        int width = 0;
+        int height = 0;
+        foreach (IconDirEntry entry in this.Entries)
+        {
+            if (entry.Width == 0)
+            {
+                width = 256;
+            }
+
+            if (entry.Height == 0)
+            {
+                height = 256;
+            }
+
+            if (width == 256 && height == 256)
+            {
+                break;
+            }
+
+            width = Math.Max(width, entry.Width);
+            height = Math.Max(height, entry.Height);
+        }
+
+        this.Dimensions = new(width, height);
     }
 
     private static int Read<T>(Stream stream, out T data, int size)
         where T : unmanaged
     {
+        // TODO: Use explicit parsing methods for each T type.
+        // See PngHeader.Parse() for example.
         Span<byte> buffer = stackalloc byte[size];
+
         _ = IconAssert.EndOfStream(stream.Read(buffer), size);
         data = MemoryMarshal.Cast<byte, T>(buffer)[0];
         return size;
@@ -121,15 +163,16 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
     {
         if (isPng)
         {
-            return new Png.PngDecoderCore(this.Options);
+            return new PngDecoderCore(this.Options);
         }
         else
         {
-            return new Bmp.BmpDecoderCore(new()
+            return new BmpDecoderCore(new()
             {
+                GeneralOptions = this.Options,
                 ProcessedAlphaMask = true,
                 SkipFileHeader = true,
-                IsDoubleHeight = true,
+                UseDoubleHeight = true,
             });
         }
     }
diff --git a/src/ImageSharp/Formats/Icon/IconFrameCompression.cs b/src/ImageSharp/Formats/Icon/IconFrameCompression.cs
index f6509f40c..5c772c3fe 100644
--- a/src/ImageSharp/Formats/Icon/IconFrameCompression.cs
+++ b/src/ImageSharp/Formats/Icon/IconFrameCompression.cs
@@ -8,11 +8,6 @@ namespace SixLabors.ImageSharp.Formats.Icon;
 /// </summary>
 public enum IconFrameCompression
 {
-    /// <summary>
-    /// Unknown
-    /// </summary>
-    Unknown,
-
     /// <summary>
     /// Bmp
     /// </summary>
diff --git a/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs b/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs
index 17e641c71..5c23388e7 100644
--- a/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs
@@ -5,6 +5,7 @@ namespace SixLabors.ImageSharp.Formats.Icon;
 
 /// <summary>
 /// IconFrameMetadata
+/// TODO: Delete this. Treat the individual metadata types as separate types so we can avoid Field1, Field2 and use strong typing with constaints.
 /// </summary>
 public abstract class IconFrameMetadata : IDeepCloneable
 {
diff --git a/src/ImageSharp/Metadata/ImageFrameMetadata.cs b/src/ImageSharp/Metadata/ImageFrameMetadata.cs
index 0567c8916..562e47803 100644
--- a/src/ImageSharp/Metadata/ImageFrameMetadata.cs
+++ b/src/ImageSharp/Metadata/ImageFrameMetadata.cs
@@ -99,9 +99,9 @@ public sealed class ImageFrameMetadata : IDeepCloneable<ImageFrameMetadata>
         return newMeta;
     }
 
-    internal void UnsafeSetFormatMetadata(
-        IImageFormat key,
-        IDeepCloneable value)
+    internal void SetFormatMetadata<TFormatMetadata, TFormatFrameMetadata>(IImageFormat<TFormatMetadata, TFormatFrameMetadata> key, TFormatFrameMetadata value)
+        where TFormatMetadata : class
+        where TFormatFrameMetadata : class, IDeepCloneable
         => this.formatMetadata[key] = value;
 
     /// <summary>
diff --git a/src/ImageSharp/Metadata/ImageMetadata.cs b/src/ImageSharp/Metadata/ImageMetadata.cs
index 6b62be08f..d9aba6631 100644
--- a/src/ImageSharp/Metadata/ImageMetadata.cs
+++ b/src/ImageSharp/Metadata/ImageMetadata.cs
@@ -215,6 +215,9 @@ public sealed class ImageMetadata : IDeepCloneable<ImageMetadata>
         metadata = default;
         return false;
     }
+    internal void SetFormatMetadata<TFormatMetadata>(IImageFormat<TFormatMetadata> key, TFormatMetadata value)
+        where TFormatMetadata : class, IDeepCloneable
+        => this.formatMetadata[key] = value;
 
     /// <inheritdoc/>
     public ImageMetadata DeepClone() => new(this);
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
index c3c9ad1c4..f78c04cdf 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
@@ -2,7 +2,6 @@
 // Licensed under the Six Labors Split License.
 
 using SixLabors.ImageSharp.Formats.Icon.Cur;
-using SixLabors.ImageSharp.Formats.Tiff;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Cur;
 
@@ -18,6 +17,10 @@ public class CurDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(CurDecoder.Instance);
 
-        image.DebugSave(provider, extension: "tiff", encoder: new TiffEncoder());
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
     }
 }
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
index 6e7b35111..86f8b003b 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
@@ -2,7 +2,6 @@
 // Licensed under the Six Labors Split License.
 
 using SixLabors.ImageSharp.Formats.Icon.Ico;
-using SixLabors.ImageSharp.Formats.Tiff;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Ico;
 
@@ -18,6 +17,8 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSave(provider, extension: "tiff", encoder: new TiffEncoder());
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
     }
 }

From 79f538723f6500350be073bf66bfc22d65784d56 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 14 Dec 2023 14:13:54 +0800
Subject: [PATCH 06/28] Handle frames exceeding 256 pixels

---
 .../Formats/Icon/IconDecoderCore.cs           | 60 ++++++++++++++-----
 1 file changed, 44 insertions(+), 16 deletions(-)

diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index d7fc25c69..874e93411 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -32,7 +32,8 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         this.ReadHeader(stream);
 
         Span<byte> flag = stackalloc byte[PngConstants.HeaderBytes.Length];
-        Image<TPixel> result = new(this.Dimensions.Width, this.Dimensions.Height);
+
+        List<(Image<TPixel> Image, bool IsPng, int Index)> decodedEntries = new(this.Entries.Length);
 
         for (int i = 0; i < this.Entries.Length; i++)
         {
@@ -54,37 +55,62 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
             stream.Seek(-PngConstants.HeaderBytes.Length, SeekOrigin.Current);
 
             bool isPng = flag.SequenceEqual(PngConstants.HeaderBytes);
-            using Image<TPixel> temp = this.GetDecoder(isPng).Decode<TPixel>(stream, cancellationToken);
 
-            ImageFrame<TPixel> source = temp.Frames.RootFrameUnsafe;
-            ImageFrame<TPixel> target = i == 0 ? result.Frames.RootFrameUnsafe : result.Frames.CreateFrame();
+            // Decode the frame into a temp image buffer. This is disposed after the frame is copied to the result.
+            Image<TPixel> temp = this.GetDecoder(isPng).Decode<TPixel>(stream, cancellationToken);
+            decodedEntries.Add((temp, isPng, i));
+
+            // Since Windows Vista, the size of an image is determined from the BITMAPINFOHEADER structure or PNG image data
+            // which technically allows storing icons with larger than 256 pixels, but such larger sizes are not recommended by Microsoft.
+            this.Dimensions = new(Math.Max(this.Dimensions.Width, temp.Size.Width), Math.Max(this.Dimensions.Height, temp.Size.Height));
+        }
 
-            // Draw the new frame at position 0,0. We capture the dimensions for cropping during encoding
-            // via the icon entry.
-            for (int h = 0; h < source.Height; h++)
+        ImageMetadata metadata = new();
+        BmpMetadata? bmpMetadata = null;
+        PngMetadata? pngMetadata = null;
+        Image<TPixel> result = new(this.Options.Configuration, metadata, decodedEntries.Select(x =>
+        {
+            ImageFrame<TPixel> target = new(this.Options.Configuration, this.Dimensions);
+            ImageFrame<TPixel> source = x.Image.Frames.RootFrameUnsafe;
+            for (int y = 0; y < source.Height; y++)
             {
-                source.PixelBuffer.DangerousGetRowSpan(h).CopyTo(target.PixelBuffer.DangerousGetRowSpan(h));
+                source.PixelBuffer.DangerousGetRowSpan(y).CopyTo(target.PixelBuffer.DangerousGetRowSpan(y));
             }
 
-            // Copy the format specific metadata to the image.
-            if (isPng)
+            // Copy the format specific frame metadata to the image.
+            if (x.IsPng)
             {
-                if (i == 0)
+                if (x.Index == 0)
                 {
-                    result.Metadata.SetFormatMetadata(PngFormat.Instance, temp.Metadata.GetPngMetadata());
+                    pngMetadata = x.Image.Metadata.GetPngMetadata();
                 }
 
+                // Bmp does not contain frame specific metadata.
                 target.Metadata.SetFormatMetadata(PngFormat.Instance, target.Metadata.GetPngFrameMetadata());
             }
-            else if (i == 0)
+            else if (x.Index == 0)
             {
-                // Bmp does not contain frame specific metadata.
-                result.Metadata.SetFormatMetadata(BmpFormat.Instance, temp.Metadata.GetBmpMetadata());
+                bmpMetadata = x.Image.Metadata.GetBmpMetadata();
             }
 
             // TODO: The inheriting decoder should be responsible for setting the actual data (FromIconDirEntry)
             // so we can avoid the protected Field1 and Field2 properties and use strong typing.
-            this.GetFrameMetadata(target.Metadata).FromIconDirEntry(entry);
+            this.GetFrameMetadata(target.Metadata).FromIconDirEntry(this.Entries[x.Index]);
+
+            x.Image.Dispose();
+
+            return target;
+        }).ToArray());
+
+        // Copy the format specific metadata to the image.
+        if (bmpMetadata != null)
+        {
+            result.Metadata.SetFormatMetadata(BmpFormat.Instance, bmpMetadata);
+        }
+
+        if (pngMetadata != null)
+        {
+            result.Metadata.SetFormatMetadata(PngFormat.Instance, pngMetadata);
         }
 
         return result;
@@ -125,6 +151,8 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         int height = 0;
         foreach (IconDirEntry entry in this.Entries)
         {
+            // Since Windows 95 size of an image in the ICONDIRENTRY structure might
+            // be set to zero, which means 256 pixels.
             if (entry.Width == 0)
             {
                 width = 256;

From a811784d34c87e46322f8b8e1d8b3f48ebe9e3ef Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 14 Dec 2023 14:13:55 +0800
Subject: [PATCH 07/28] Update TgaFileHeaderTests.cs

---
 tests/ImageSharp.Tests/Formats/Tga/TgaFileHeaderTests.cs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tests/ImageSharp.Tests/Formats/Tga/TgaFileHeaderTests.cs b/tests/ImageSharp.Tests/Formats/Tga/TgaFileHeaderTests.cs
index bf24ba350..2f96b6d43 100644
--- a/tests/ImageSharp.Tests/Formats/Tga/TgaFileHeaderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Tga/TgaFileHeaderTests.cs
@@ -9,6 +9,8 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tga;
 [Trait("Format", "Tga")]
 public class TgaFileHeaderTests
 {
+    // TODO: Some of these clash with the ICO magic bytes. Check correctness.
+    // https://en.wikipedia.org/wiki/Truevision_TGA#Header
     [Theory]
     [InlineData(new byte[] { 0, 0, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 250, 0, 195, 0, 32, 8 })] // invalid tga image type.
     [InlineData(new byte[] { 0, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 250, 0, 195, 0, 32, 8 })] // invalid colormap type.

From 43ea25fe8b612cf1da5713b1149ac2a078be64e8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:13:55 +0800
Subject: [PATCH 08/28] Add Parse Method and Check Stream
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 .../Formats/Icon/IconDecoderCore.cs           | 24 +++++++------------
 src/ImageSharp/Formats/Icon/IconDir.cs        | 15 +++++++++---
 src/ImageSharp/Formats/Icon/IconDirEntry.cs   |  3 +++
 3 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index 874e93411..1077bde51 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -139,12 +139,18 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
 
     protected void ReadHeader(Stream stream)
     {
-        // TODO: Check length and throw if the header cannot be read.
-        _ = Read(stream, out this.fileHeader, IconDir.Size);
+        Span<byte> buffer = stackalloc byte[IconDirEntry.Size];
+
+        // ICONDIR
+        _ = IconAssert.EndOfStream(stream.Read(buffer[..IconDir.Size]), IconDir.Size);
+        this.fileHeader = IconDir.Parse(buffer);
+
+        // ICONDIRENTRY
         this.Entries = new IconDirEntry[this.FileHeader.Count];
         for (int i = 0; i < this.Entries.Length; i++)
         {
-            _ = Read(stream, out this.Entries[i], IconDirEntry.Size);
+            _ = IconAssert.EndOfStream(stream.Read(buffer[..IconDirEntry.Size]), IconDirEntry.Size);
+            this.Entries[i] = IconDirEntry.Parse(buffer);
         }
 
         int width = 0;
@@ -175,18 +181,6 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         this.Dimensions = new(width, height);
     }
 
-    private static int Read<T>(Stream stream, out T data, int size)
-        where T : unmanaged
-    {
-        // TODO: Use explicit parsing methods for each T type.
-        // See PngHeader.Parse() for example.
-        Span<byte> buffer = stackalloc byte[size];
-
-        _ = IconAssert.EndOfStream(stream.Read(buffer), size);
-        data = MemoryMarshal.Cast<byte, T>(buffer)[0];
-        return size;
-    }
-
     private IImageDecoderInternals GetDecoder(bool isPng)
     {
         if (isPng)
diff --git a/src/ImageSharp/Formats/Icon/IconDir.cs b/src/ImageSharp/Formats/Icon/IconDir.cs
index f1281a568..53b87bc9f 100644
--- a/src/ImageSharp/Formats/Icon/IconDir.cs
+++ b/src/ImageSharp/Formats/Icon/IconDir.cs
@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
 using System.Runtime.InteropServices;
@@ -15,12 +15,21 @@ internal struct IconDir
 
     public IconDir(IconFileType type)
         : this(type, 0)
-        => this.Type = type;
+    {
+    }
 
     public IconDir(IconFileType type, ushort count)
+        : this(0, type, count)
+    {
+    }
+
+    public IconDir(ushort reserved, IconFileType type, ushort count)
     {
-        this.Reserved = 0;
+        this.Reserved = reserved;
         this.Type = type;
         this.Count = count;
     }
+
+    public static IconDir Parse(in ReadOnlySpan<byte> data)
+        => MemoryMarshal.Cast<byte, IconDir>(data)[0];
 }
diff --git a/src/ImageSharp/Formats/Icon/IconDirEntry.cs b/src/ImageSharp/Formats/Icon/IconDirEntry.cs
index 43254f89d..edd778f7e 100644
--- a/src/ImageSharp/Formats/Icon/IconDirEntry.cs
+++ b/src/ImageSharp/Formats/Icon/IconDirEntry.cs
@@ -25,4 +25,7 @@ internal struct IconDirEntry
     public uint BytesInRes;
 
     public uint ImageOffset;
+
+    public static IconDirEntry Parse(in ReadOnlySpan<byte> data)
+        => MemoryMarshal.Cast<byte, IconDirEntry>(data)[0];
 }

From 05d33f2895db1505940b92427b164091088cece6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:13:56 +0800
Subject: [PATCH 09/28] Remove IconFrameMetadata
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 .../Formats/Icon/Cur/CurDecoderCore.cs        |   2 +-
 .../Formats/Icon/Cur/CurFrameMetadata.cs      |  90 ++++++++++++---
 .../Formats/Icon/Ico/IcoDecoderCore.cs        |   3 +-
 .../Formats/Icon/Ico/IcoFrameMetadata.cs      |  80 +++++++++++---
 .../Formats/Icon/IconDecoderCore.cs           |   9 +-
 .../Formats/Icon/IconFrameMetadata.cs         | 104 ------------------
 6 files changed, 140 insertions(+), 148 deletions(-)
 delete mode 100644 src/ImageSharp/Formats/Icon/IconFrameMetadata.cs

diff --git a/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs b/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
index 44fcc8fcc..afd751279 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
@@ -14,5 +14,5 @@ internal sealed class CurDecoderCore : IconDecoderCore
     {
     }
 
-    protected override IconFrameMetadata GetFrameMetadata(ImageFrameMetadata metadata) => metadata.GetCurMetadata();
+    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry) => metadata.GetCurMetadata().FromIconDirEntry(entry);
 }
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs b/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
index 60ced16ea..2d1c22776 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
@@ -4,9 +4,9 @@
 namespace SixLabors.ImageSharp.Formats.Icon.Cur;
 
 /// <summary>
-/// IcoFrameMetadata. TODO: Remove base class and merge into this class.
+/// IcoFrameMetadata.
 /// </summary>
-public class CurFrameMetadata : IconFrameMetadata, IDeepCloneable<CurFrameMetadata>, IDeepCloneable
+public class CurFrameMetadata : IDeepCloneable<CurFrameMetadata>, IDeepCloneable
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="CurFrameMetadata"/> class.
@@ -15,38 +15,92 @@ public class CurFrameMetadata : IconFrameMetadata, IDeepCloneable<CurFrameMetada
     {
     }
 
-    /// <summary>
-    /// Initializes a new instance of the <see cref="CurFrameMetadata"/> class.
-    /// </summary>
-    /// <param name="metadata">metadata</param>
-    public CurFrameMetadata(IconFrameMetadata metadata)
-        : base(metadata)
-    {
-    }
-
     /// <summary>
     /// Initializes a new instance of the <see cref="CurFrameMetadata"/> class.
     /// </summary>
     /// <param name="width">width</param>
     /// <param name="height">height</param>
     /// <param name="colorCount">colorCount</param>
-    /// <param name="field1">field1</param>
-    /// <param name="field2">field2</param>
-    public CurFrameMetadata(byte width, byte height, byte colorCount, ushort field1, ushort field2)
-        : base(width, height, colorCount, field1, field2)
+    /// <param name="hotspotX">hotspotX</param>
+    /// <param name="hotspotY">hotspotY</param>
+    public CurFrameMetadata(byte width, byte height, byte colorCount, ushort hotspotX, ushort hotspotY)
     {
+        this.EncodingWidth = width;
+        this.EncodingHeight = height;
+        this.ColorCount = colorCount;
+        this.HotspotX = hotspotX;
+        this.HotspotY = hotspotY;
     }
 
+    /// <inheritdoc cref="CurFrameMetadata()"/>
+    public CurFrameMetadata(CurFrameMetadata metadata)
+    {
+        this.EncodingWidth = metadata.EncodingWidth;
+        this.EncodingHeight = metadata.EncodingHeight;
+        this.ColorCount = metadata.ColorCount;
+        this.HotspotX = metadata.HotspotX;
+        this.HotspotY = metadata.HotspotY;
+        this.Compression = metadata.Compression;
+    }
+
+    /// <summary>
+    /// Gets or sets icoFrameCompression.
+    /// </summary>
+    public IconFrameCompression Compression { get; set; }
+
+    /// <summary>
+    /// Gets or sets ColorCount field. <br />
+    /// Specifies number of colors in the color palette. Should be 0 if the image does not use a color palette.
+    /// </summary>
+    // TODO: BmpMetadata does not supported palette yet.
+    public byte ColorCount { get; set; }
+
     /// <summary>
     /// Gets or sets Specifies the horizontal coordinates of the hotspot in number of pixels from the left.
     /// </summary>
-    public ushort HotspotX { get => this.Field1; set => this.Field1 = value; }
+    public ushort HotspotX { get; set; }
 
     /// <summary>
     /// Gets or sets Specifies the vertical coordinates of the hotspot in number of pixels from the top.
     /// </summary>
-    public ushort HotspotY { get => this.Field2; set => this.Field2 = value; }
+    public ushort HotspotY { get; set; }
+
+    /// <summary>
+    /// Gets or sets Height field. <br />
+    /// Specifies image height in pixels. Can be any number between 0 and 255. Value 0 means image height is 256 pixels.
+    /// </summary>
+    public byte EncodingHeight { get; set; }
+
+    /// <summary>
+    /// Gets or sets Width field. <br />
+    /// Specifies image width in pixels. Can be any number between 0 and 255. Value 0 means image width is 256 pixels.
+    /// </summary>
+    public byte EncodingWidth { get; set; }
+
+    /// <inheritdoc cref="Bmp.BmpMetadata.BitsPerPixel" />
+    public Bmp.BmpBitsPerPixel BitsPerPixel { get; set; } = Bmp.BmpBitsPerPixel.Pixel24;
 
     /// <inheritdoc/>
-    public override CurFrameMetadata DeepClone() => new(this);
+    public CurFrameMetadata DeepClone() => new(this);
+
+    /// <inheritdoc/>
+    IDeepCloneable IDeepCloneable.DeepClone() => this.DeepClone();
+
+    internal void FromIconDirEntry(in IconDirEntry entry)
+    {
+        this.EncodingWidth = entry.Width;
+        this.EncodingHeight = entry.Height;
+        this.ColorCount = entry.ColorCount;
+        this.HotspotX = entry.Planes;
+        this.HotspotY = entry.BitCount;
+    }
+
+    internal IconDirEntry ToIconDirEntry() => new()
+    {
+        Width = this.EncodingWidth,
+        Height = this.EncodingHeight,
+        ColorCount = this.ColorCount,
+        Planes = this.HotspotX,
+        BitCount = this.HotspotY,
+    };
 }
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs b/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
index 677a9c07a..4884fdf9a 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
@@ -14,5 +14,6 @@ internal sealed class IcoDecoderCore : IconDecoderCore
     {
     }
 
-    protected override IconFrameMetadata GetFrameMetadata(ImageFrameMetadata metadata) => metadata.GetIcoMetadata();
+    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry)
+        => metadata.GetIcoMetadata().FromIconDirEntry(entry);
 }
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs b/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
index 4f557715d..82e3c1db3 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
@@ -6,7 +6,7 @@ namespace SixLabors.ImageSharp.Formats.Icon.Ico;
 /// <summary>
 /// IcoFrameMetadata. TODO: Remove base class and merge into this class.
 /// </summary>
-public class IcoFrameMetadata : IconFrameMetadata, IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
+public class IcoFrameMetadata : IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="IcoFrameMetadata"/> class.
@@ -15,34 +15,78 @@ public class IcoFrameMetadata : IconFrameMetadata, IDeepCloneable<IcoFrameMetada
     {
     }
 
-    /// <summary>
-    /// Initializes a new instance of the <see cref="IcoFrameMetadata"/> class.
-    /// </summary>
-    /// <param name="metadata">metadata</param>
-    public IcoFrameMetadata(IconFrameMetadata metadata)
-        : base(metadata)
-    {
-    }
-
     /// <summary>
     /// Initializes a new instance of the <see cref="IcoFrameMetadata"/> class.
     /// </summary>
     /// <param name="width">width</param>
     /// <param name="height">height</param>
     /// <param name="colorCount">colorCount</param>
-    /// <param name="field1">field1</param>
-    /// <param name="field2">field2</param>
-    public IcoFrameMetadata(byte width, byte height, byte colorCount, ushort field1, ushort field2)
-        : base(width, height, colorCount, field1, field2)
+    public IcoFrameMetadata(byte width, byte height, byte colorCount)
     {
+        this.EncodingWidth = width;
+        this.EncodingHeight = height;
+        this.ColorCount = colorCount;
     }
 
+    /// <inheritdoc cref="IcoFrameMetadata()"/>
+    public IcoFrameMetadata(IcoFrameMetadata metadata)
+    {
+        this.EncodingWidth = metadata.EncodingWidth;
+        this.EncodingHeight = metadata.EncodingHeight;
+        this.ColorCount = metadata.ColorCount;
+        this.Compression = metadata.Compression;
+    }
+
+    /// <summary>
+    /// Gets or sets icoFrameCompression.
+    /// </summary>
+    public IconFrameCompression Compression { get; set; }
+
+    /// <summary>
+    /// Gets or sets ColorCount field. <br />
+    /// Specifies number of colors in the color palette. Should be 0 if the image does not use a color palette.
+    /// </summary>
+    // TODO: BmpMetadata does not supported palette yet.
+    public byte ColorCount { get; set; }
+
     /// <summary>
-    /// Gets or sets the bits per pixel.
-    /// TODO: This needs to be constrained and calculated using the metadata returned from the png/bmp.
+    /// Gets or sets Height field. <br />
+    /// Specifies image height in pixels. Can be any number between 0 and 255. Value 0 means image height is 256 pixels.
     /// </summary>
-    public ushort BitCount { get => this.Field2; set => this.Field2 = value; }
+    public byte EncodingHeight { get; set; }
+
+    /// <summary>
+    /// Gets or sets Width field. <br />
+    /// Specifies image width in pixels. Can be any number between 0 and 255. Value 0 means image width is 256 pixels.
+    /// </summary>
+    public byte EncodingWidth { get; set; }
+
+    /// <inheritdoc cref="Bmp.BmpMetadata.BitsPerPixel" />
+    public Bmp.BmpBitsPerPixel BitsPerPixel { get; set; } = Bmp.BmpBitsPerPixel.Pixel24;
 
     /// <inheritdoc/>
-    public override IcoFrameMetadata DeepClone() => new(this);
+    public IcoFrameMetadata DeepClone() => new(this);
+
+    /// <inheritdoc/>
+    IDeepCloneable IDeepCloneable.DeepClone() => this.DeepClone();
+
+    internal void FromIconDirEntry(in IconDirEntry entry)
+    {
+        this.EncodingWidth = entry.Width;
+        this.EncodingHeight = entry.Height;
+        this.ColorCount = entry.ColorCount;
+    }
+
+    internal IconDirEntry ToIconDirEntry() => new()
+    {
+        Width = this.EncodingWidth,
+        Height = this.EncodingHeight,
+        ColorCount = this.ColorCount,
+        Planes = 1,
+        BitCount = this.Compression switch
+        {
+            IconFrameCompression.Bmp => (ushort)this.BitsPerPixel,
+            _ => 0,
+        },
+    };
 }
diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index 1077bde51..21c0a3bc4 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -93,9 +93,7 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
                 bmpMetadata = x.Image.Metadata.GetBmpMetadata();
             }
 
-            // TODO: The inheriting decoder should be responsible for setting the actual data (FromIconDirEntry)
-            // so we can avoid the protected Field1 and Field2 properties and use strong typing.
-            this.GetFrameMetadata(target.Metadata).FromIconDirEntry(this.Entries[x.Index]);
+            this.SetFrameMetadata(target.Metadata, this.Entries[x.Index]);
 
             x.Image.Dispose();
 
@@ -127,15 +125,14 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
             // TODO: Use the Identify methods in each decoder to return the
             // format specific metadata for the image and frame.
             frames[i] = new();
-            IconFrameMetadata icoFrameMetadata = this.GetFrameMetadata(frames[i]);
-            icoFrameMetadata.FromIconDirEntry(this.Entries[i]);
+            this.SetFrameMetadata(frames[i], this.Entries[i]);
         }
 
         // TODO: Use real values from the metadata.
         return new(new(32), new(0), metadata, frames);
     }
 
-    protected abstract IconFrameMetadata GetFrameMetadata(ImageFrameMetadata metadata);
+    protected abstract void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry);
 
     protected void ReadHeader(Stream stream)
     {
diff --git a/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs b/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs
deleted file mode 100644
index 5c23388e7..000000000
--- a/src/ImageSharp/Formats/Icon/IconFrameMetadata.cs
+++ /dev/null
@@ -1,104 +0,0 @@
-// Copyright (c) Six Labors.
-// Licensed under the Six Labors Split License.
-
-namespace SixLabors.ImageSharp.Formats.Icon;
-
-/// <summary>
-/// IconFrameMetadata
-/// TODO: Delete this. Treat the individual metadata types as separate types so we can avoid Field1, Field2 and use strong typing with constaints.
-/// </summary>
-public abstract class IconFrameMetadata : IDeepCloneable
-{
-    /// <summary>
-    /// Initializes a new instance of the <see cref="IconFrameMetadata"/> class.
-    /// </summary>
-    protected IconFrameMetadata()
-    {
-    }
-
-    /// <summary>
-    /// Initializes a new instance of the <see cref="IconFrameMetadata"/> class.
-    /// </summary>
-    /// <param name="width">width</param>
-    /// <param name="height">height</param>
-    /// <param name="colorCount">colorCount</param>
-    /// <param name="field1">field1</param>
-    /// <param name="field2">field2</param>
-    protected IconFrameMetadata(byte width, byte height, byte colorCount, ushort field1, ushort field2)
-    {
-        this.EncodingWidth = width;
-        this.EncodingHeight = height;
-        this.ColorCount = colorCount;
-        this.Field1 = field1;
-        this.Field2 = field2;
-    }
-
-    /// <inheritdoc cref="IconFrameMetadata()"/>
-    protected IconFrameMetadata(IconFrameMetadata metadata)
-    {
-        this.EncodingWidth = metadata.EncodingWidth;
-        this.EncodingHeight = metadata.EncodingHeight;
-        this.ColorCount = metadata.ColorCount;
-        this.Field1 = metadata.Field1;
-        this.Field2 = metadata.Field2;
-    }
-
-    /// <summary>
-    /// Gets or sets icoFrameCompression.
-    /// </summary>
-    public IconFrameCompression Compression { get; protected set; }
-
-    /// <summary>
-    /// Gets or sets ColorCount field. <br />
-    /// Specifies number of colors in the color palette. Should be 0 if the image does not use a color palette.
-    /// </summary>
-    // TODO: BmpMetadata does not supported palette yet.
-    public byte ColorCount { get; set; }
-
-    /// <summary>
-    /// Gets or sets Planes field. <br />
-    /// In ICO format: Specifies color planes. Should be 0 or 1. <br />
-    /// In CUR format: Specifies the horizontal coordinates of the hotspot in number of pixels from the left.
-    /// </summary>
-    protected ushort Field1 { get; set; }
-
-    /// <summary>
-    /// Gets or sets BitCount field. <br />
-    /// In ICO format: Specifies bits per pixel. <br />
-    /// In CUR format: Specifies the vertical coordinates of the hotspot in number of pixels from the top.
-    /// </summary>
-    protected ushort Field2 { get; set; }
-
-    /// <summary>
-    /// Gets or sets Height field. <br />
-    /// Specifies image height in pixels. Can be any number between 0 and 255. Value 0 means image height is 256 pixels.
-    /// </summary>
-    public byte EncodingHeight { get; set; }
-
-    /// <summary>
-    /// Gets or sets Width field. <br />
-    /// Specifies image width in pixels. Can be any number between 0 and 255. Value 0 means image width is 256 pixels.
-    /// </summary>
-    public byte EncodingWidth { get; set; }
-
-    /// <inheritdoc/>
-    public abstract IDeepCloneable DeepClone();
-
-    internal void FromIconDirEntry(in IconDirEntry metadata)
-    {
-        this.EncodingWidth = metadata.Width;
-        this.EncodingHeight = metadata.Height;
-        this.ColorCount = metadata.ColorCount;
-        this.Field1 = metadata.Planes;
-        this.Field2 = metadata.BitCount;
-    }
-
-    internal IconDirEntry ToIconDirEntry() => new()
-    {
-        Width = this.EncodingWidth,
-        Height = this.EncodingHeight,
-        ColorCount = this.ColorCount,
-        Planes = this.Field1,
-        BitCount = this.Field2,
-    };
-}

From 729d64ec757536c30c3f3ed5255f2460762206d5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:13:56 +0800
Subject: [PATCH 10/28] Refactor SetFrameMetadata
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 .../Formats/Icon/Cur/CurDecoderCore.cs        |  8 ++-
 .../Formats/Icon/Ico/IcoDecoderCore.cs        |  9 ++-
 .../Formats/Icon/IconDecoderCore.cs           | 64 +++++++++++++------
 3 files changed, 60 insertions(+), 21 deletions(-)

diff --git a/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs b/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
index afd751279..2ed89483a 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
@@ -14,5 +14,11 @@ internal sealed class CurDecoderCore : IconDecoderCore
     {
     }
 
-    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry) => metadata.GetCurMetadata().FromIconDirEntry(entry);
+    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, Bmp.BmpBitsPerPixel bitsPerPixel)
+    {
+        CurFrameMetadata curFrameMetadata = metadata.GetCurMetadata();
+        curFrameMetadata.FromIconDirEntry(entry);
+        curFrameMetadata.Compression = compression;
+        curFrameMetadata.BitsPerPixel = bitsPerPixel;
+    }
 }
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs b/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
index 4884fdf9a..c7841ce39 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
@@ -14,6 +14,11 @@ internal sealed class IcoDecoderCore : IconDecoderCore
     {
     }
 
-    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry)
-        => metadata.GetIcoMetadata().FromIconDirEntry(entry);
+    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, Bmp.BmpBitsPerPixel bitsPerPixel)
+    {
+        IcoFrameMetadata icoFrameMetadata = metadata.GetIcoMetadata();
+        icoFrameMetadata.FromIconDirEntry(entry);
+        icoFrameMetadata.Compression = compression;
+        icoFrameMetadata.BitsPerPixel = bitsPerPixel;
+    }
 }
diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index 21c0a3bc4..6af9553cc 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -33,7 +33,7 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
 
         Span<byte> flag = stackalloc byte[PngConstants.HeaderBytes.Length];
 
-        List<(Image<TPixel> Image, bool IsPng, int Index)> decodedEntries = new(this.Entries.Length);
+        List<(Image<TPixel> Image, IconFrameCompression Compression, int Index)> decodedEntries = new(this.Entries.Length);
 
         for (int i = 0; i < this.Entries.Length; i++)
         {
@@ -58,7 +58,7 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
 
             // Decode the frame into a temp image buffer. This is disposed after the frame is copied to the result.
             Image<TPixel> temp = this.GetDecoder(isPng).Decode<TPixel>(stream, cancellationToken);
-            decodedEntries.Add((temp, isPng, i));
+            decodedEntries.Add((temp, isPng ? IconFrameCompression.Png : IconFrameCompression.Bmp, i));
 
             // Since Windows Vista, the size of an image is determined from the BITMAPINFOHEADER structure or PNG image data
             // which technically allows storing icons with larger than 256 pixels, but such larger sizes are not recommended by Microsoft.
@@ -66,10 +66,10 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         }
 
         ImageMetadata metadata = new();
-        BmpMetadata? bmpMetadata = null;
         PngMetadata? pngMetadata = null;
         Image<TPixel> result = new(this.Options.Configuration, metadata, decodedEntries.Select(x =>
         {
+            BmpBitsPerPixel bitsPerPixel = default;
             ImageFrame<TPixel> target = new(this.Options.Configuration, this.Dimensions);
             ImageFrame<TPixel> source = x.Image.Frames.RootFrameUnsafe;
             for (int y = 0; y < source.Height; y++)
@@ -78,7 +78,7 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
             }
 
             // Copy the format specific frame metadata to the image.
-            if (x.IsPng)
+            if (x.Compression is IconFrameCompression.Png)
             {
                 if (x.Index == 0)
                 {
@@ -88,12 +88,12 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
                 // Bmp does not contain frame specific metadata.
                 target.Metadata.SetFormatMetadata(PngFormat.Instance, target.Metadata.GetPngFrameMetadata());
             }
-            else if (x.Index == 0)
+            else
             {
-                bmpMetadata = x.Image.Metadata.GetBmpMetadata();
+                bitsPerPixel = x.Image.Metadata.GetBmpMetadata().BitsPerPixel;
             }
 
-            this.SetFrameMetadata(target.Metadata, this.Entries[x.Index]);
+            this.SetFrameMetadata(target.Metadata, this.Entries[x.Index], x.Compression, bitsPerPixel);
 
             x.Image.Dispose();
 
@@ -101,11 +101,6 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         }).ToArray());
 
         // Copy the format specific metadata to the image.
-        if (bmpMetadata != null)
-        {
-            result.Metadata.SetFormatMetadata(BmpFormat.Instance, bmpMetadata);
-        }
-
         if (pngMetadata != null)
         {
             result.Metadata.SetFormatMetadata(PngFormat.Instance, pngMetadata);
@@ -116,23 +111,56 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
 
     public ImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken)
     {
+        // Stream may not at 0.
+        long basePosition = stream.Position;
         this.ReadHeader(stream);
 
+        Span<byte> flag = stackalloc byte[PngConstants.HeaderBytes.Length];
+
         ImageMetadata metadata = new();
         ImageFrameMetadata[] frames = new ImageFrameMetadata[this.FileHeader.Count];
         for (int i = 0; i < frames.Length; i++)
         {
-            // TODO: Use the Identify methods in each decoder to return the
-            // format specific metadata for the image and frame.
+            BmpBitsPerPixel bitsPerPixel = default;
+            ref IconDirEntry entry = ref this.Entries[i];
+
+            // If we hit the end of the stream we should break.
+            if (stream.Seek(basePosition + entry.ImageOffset, SeekOrigin.Begin) >= stream.Length)
+            {
+                break;
+            }
+
+            // There should always be enough bytes for this regardless of the entry type.
+            if (stream.Read(flag) != PngConstants.HeaderBytes.Length)
+            {
+                break;
+            }
+
+            // Reset the stream position.
+            stream.Seek(-PngConstants.HeaderBytes.Length, SeekOrigin.Current);
+
+            bool isPng = flag.SequenceEqual(PngConstants.HeaderBytes);
+
+            // Decode the frame into a temp image buffer. This is disposed after the frame is copied to the result.
+            ImageInfo temp = this.GetDecoder(isPng).Identify(stream, cancellationToken);
+
             frames[i] = new();
-            this.SetFrameMetadata(frames[i], this.Entries[i]);
+            if (isPng)
+            {
+                bitsPerPixel = temp.Metadata.GetBmpMetadata().BitsPerPixel;
+            }
+
+            this.SetFrameMetadata(frames[i], this.Entries[i], isPng ? IconFrameCompression.Png : IconFrameCompression.Bmp, bitsPerPixel);
+
+            // Since Windows Vista, the size of an image is determined from the BITMAPINFOHEADER structure or PNG image data
+            // which technically allows storing icons with larger than 256 pixels, but such larger sizes are not recommended by Microsoft.
+            this.Dimensions = new(Math.Max(this.Dimensions.Width, temp.Size.Width), Math.Max(this.Dimensions.Height, temp.Size.Height));
         }
 
-        // TODO: Use real values from the metadata.
-        return new(new(32), new(0), metadata, frames);
+        return new(new(32), this.Dimensions, metadata, frames);
     }
 
-    protected abstract void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry);
+    protected abstract void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, BmpBitsPerPixel bitsPerPixel);
 
     protected void ReadHeader(Stream stream)
     {

From 63da967c7f8e41467243993ef64cc45079f46b8c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:13:57 +0800
Subject: [PATCH 11/28] Flatten namespace.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 src/ImageSharp/Configuration.cs                              | 4 ++--
 .../Formats/{Icon => }/Cur/CurConfigurationModule.cs         | 4 +++-
 src/ImageSharp/Formats/{Icon => }/Cur/CurConstants.cs        | 2 +-
 src/ImageSharp/Formats/{Icon => }/Cur/CurDecoder.cs          | 2 +-
 src/ImageSharp/Formats/{Icon => }/Cur/CurDecoderCore.cs      | 5 ++---
 src/ImageSharp/Formats/{Icon => }/Cur/CurFormat.cs           | 2 +-
 src/ImageSharp/Formats/{Icon => }/Cur/CurFrameMetadata.cs    | 4 +++-
 src/ImageSharp/Formats/{Icon => }/Cur/CurMetadata.cs         | 2 +-
 src/ImageSharp/Formats/{Icon => }/Cur/MetadataExtensions.cs  | 2 +-
 .../Formats/{Icon => }/Ico/IcoConfigurationModule.cs         | 4 +++-
 src/ImageSharp/Formats/{Icon => }/Ico/IcoConstants.cs        | 2 +-
 src/ImageSharp/Formats/{Icon => }/Ico/IcoDecoder.cs          | 2 +-
 src/ImageSharp/Formats/{Icon => }/Ico/IcoDecoderCore.cs      | 5 ++---
 src/ImageSharp/Formats/{Icon => }/Ico/IcoFormat.cs           | 2 +-
 src/ImageSharp/Formats/{Icon => }/Ico/IcoFrameMetadata.cs    | 4 +++-
 src/ImageSharp/Formats/{Icon => }/Ico/IcoMetadata.cs         | 2 +-
 src/ImageSharp/Formats/{Icon => }/Ico/MetadataExtensions.cs  | 2 +-
 tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs   | 4 +---
 tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs   | 2 +-
 19 files changed, 30 insertions(+), 26 deletions(-)
 rename src/ImageSharp/Formats/{Icon => }/Cur/CurConfigurationModule.cs (88%)
 rename src/ImageSharp/Formats/{Icon => }/Cur/CurConstants.cs (93%)
 rename src/ImageSharp/Formats/{Icon => }/Cur/CurDecoder.cs (96%)
 rename src/ImageSharp/Formats/{Icon => }/Cur/CurDecoderCore.cs (84%)
 rename src/ImageSharp/Formats/{Icon => }/Cur/CurFormat.cs (95%)
 rename src/ImageSharp/Formats/{Icon => }/Cur/CurFrameMetadata.cs (97%)
 rename src/ImageSharp/Formats/{Icon => }/Cur/CurMetadata.cs (89%)
 rename src/ImageSharp/Formats/{Icon => }/Cur/MetadataExtensions.cs (97%)
 rename src/ImageSharp/Formats/{Icon => }/Ico/IcoConfigurationModule.cs (88%)
 rename src/ImageSharp/Formats/{Icon => }/Ico/IcoConstants.cs (95%)
 rename src/ImageSharp/Formats/{Icon => }/Ico/IcoDecoder.cs (96%)
 rename src/ImageSharp/Formats/{Icon => }/Ico/IcoDecoderCore.cs (84%)
 rename src/ImageSharp/Formats/{Icon => }/Ico/IcoFormat.cs (95%)
 rename src/ImageSharp/Formats/{Icon => }/Ico/IcoFrameMetadata.cs (97%)
 rename src/ImageSharp/Formats/{Icon => }/Ico/IcoMetadata.cs (89%)
 rename src/ImageSharp/Formats/{Icon => }/Ico/MetadataExtensions.cs (97%)

diff --git a/src/ImageSharp/Configuration.cs b/src/ImageSharp/Configuration.cs
index d6cfd480d..1d9f3bb85 100644
--- a/src/ImageSharp/Configuration.cs
+++ b/src/ImageSharp/Configuration.cs
@@ -4,9 +4,9 @@
 using System.Collections.Concurrent;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Bmp;
+using SixLabors.ImageSharp.Formats.Cur;
 using SixLabors.ImageSharp.Formats.Gif;
-using SixLabors.ImageSharp.Formats.Icon.Cur;
-using SixLabors.ImageSharp.Formats.Icon.Ico;
+using SixLabors.ImageSharp.Formats.Ico;
 using SixLabors.ImageSharp.Formats.Jpeg;
 using SixLabors.ImageSharp.Formats.Pbm;
 using SixLabors.ImageSharp.Formats.Png;
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurConfigurationModule.cs b/src/ImageSharp/Formats/Cur/CurConfigurationModule.cs
similarity index 88%
rename from src/ImageSharp/Formats/Icon/Cur/CurConfigurationModule.cs
rename to src/ImageSharp/Formats/Cur/CurConfigurationModule.cs
index c975bc609..1c7db4bab 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurConfigurationModule.cs
+++ b/src/ImageSharp/Formats/Cur/CurConfigurationModule.cs
@@ -1,7 +1,9 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+using SixLabors.ImageSharp.Formats.Icon;
+
+namespace SixLabors.ImageSharp.Formats.Cur;
 
 /// <summary>
 /// Registers the image encoders, decoders and mime type detectors for the Ico format.
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurConstants.cs b/src/ImageSharp/Formats/Cur/CurConstants.cs
similarity index 93%
rename from src/ImageSharp/Formats/Icon/Cur/CurConstants.cs
rename to src/ImageSharp/Formats/Cur/CurConstants.cs
index 701b40cf4..6efd2817c 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurConstants.cs
+++ b/src/ImageSharp/Formats/Cur/CurConstants.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+namespace SixLabors.ImageSharp.Formats.Cur;
 
 /// <summary>
 /// Defines constants relating to ICOs
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurDecoder.cs b/src/ImageSharp/Formats/Cur/CurDecoder.cs
similarity index 96%
rename from src/ImageSharp/Formats/Icon/Cur/CurDecoder.cs
rename to src/ImageSharp/Formats/Cur/CurDecoder.cs
index ceefdcaba..cbe646c47 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurDecoder.cs
+++ b/src/ImageSharp/Formats/Cur/CurDecoder.cs
@@ -3,7 +3,7 @@
 
 using SixLabors.ImageSharp.PixelFormats;
 
-namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+namespace SixLabors.ImageSharp.Formats.Cur;
 
 /// <summary>
 /// Decoder for generating an image out of a ico encoded stream.
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs b/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
similarity index 84%
rename from src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
rename to src/ImageSharp/Formats/Cur/CurDecoderCore.cs
index 2ed89483a..4c0224652 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurDecoderCore.cs
+++ b/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
@@ -1,11 +1,10 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Formats.Icon;
 using SixLabors.ImageSharp.Metadata;
 
-// TODO: flatten namespace.
-// namespace SixLabors.ImageSharp.Formats.Cur;
-namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+namespace SixLabors.ImageSharp.Formats.Cur;
 
 internal sealed class CurDecoderCore : IconDecoderCore
 {
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurFormat.cs b/src/ImageSharp/Formats/Cur/CurFormat.cs
similarity index 95%
rename from src/ImageSharp/Formats/Icon/Cur/CurFormat.cs
rename to src/ImageSharp/Formats/Cur/CurFormat.cs
index 1e5758bc4..af93382ec 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurFormat.cs
+++ b/src/ImageSharp/Formats/Cur/CurFormat.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+namespace SixLabors.ImageSharp.Formats.Cur;
 
 /// <summary>
 /// Registers the image encoders, decoders and mime type detectors for the ICO format.
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs b/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs
similarity index 97%
rename from src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
rename to src/ImageSharp/Formats/Cur/CurFrameMetadata.cs
index 2d1c22776..e8f3cfe8e 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs
@@ -1,7 +1,9 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+using SixLabors.ImageSharp.Formats.Icon;
+
+namespace SixLabors.ImageSharp.Formats.Cur;
 
 /// <summary>
 /// IcoFrameMetadata.
diff --git a/src/ImageSharp/Formats/Icon/Cur/CurMetadata.cs b/src/ImageSharp/Formats/Cur/CurMetadata.cs
similarity index 89%
rename from src/ImageSharp/Formats/Icon/Cur/CurMetadata.cs
rename to src/ImageSharp/Formats/Cur/CurMetadata.cs
index ed3c322b4..5c3486d4a 100644
--- a/src/ImageSharp/Formats/Icon/Cur/CurMetadata.cs
+++ b/src/ImageSharp/Formats/Cur/CurMetadata.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+namespace SixLabors.ImageSharp.Formats.Cur;
 
 /// <summary>
 /// Provides Ico specific metadata information for the image.
diff --git a/src/ImageSharp/Formats/Icon/Cur/MetadataExtensions.cs b/src/ImageSharp/Formats/Cur/MetadataExtensions.cs
similarity index 97%
rename from src/ImageSharp/Formats/Icon/Cur/MetadataExtensions.cs
rename to src/ImageSharp/Formats/Cur/MetadataExtensions.cs
index 400ece648..2b410a0f9 100644
--- a/src/ImageSharp/Formats/Icon/Cur/MetadataExtensions.cs
+++ b/src/ImageSharp/Formats/Cur/MetadataExtensions.cs
@@ -4,7 +4,7 @@
 using System.Diagnostics.CodeAnalysis;
 using SixLabors.ImageSharp.Metadata;
 
-namespace SixLabors.ImageSharp.Formats.Icon.Cur;
+namespace SixLabors.ImageSharp.Formats.Cur;
 
 /// <summary>
 /// Extension methods for the <see cref="ImageMetadata"/> type.
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoConfigurationModule.cs b/src/ImageSharp/Formats/Ico/IcoConfigurationModule.cs
similarity index 88%
rename from src/ImageSharp/Formats/Icon/Ico/IcoConfigurationModule.cs
rename to src/ImageSharp/Formats/Ico/IcoConfigurationModule.cs
index 7074189c7..b27d91465 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoConfigurationModule.cs
+++ b/src/ImageSharp/Formats/Ico/IcoConfigurationModule.cs
@@ -1,7 +1,9 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+using SixLabors.ImageSharp.Formats.Icon;
+
+namespace SixLabors.ImageSharp.Formats.Ico;
 
 /// <summary>
 /// Registers the image encoders, decoders and mime type detectors for the Ico format.
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoConstants.cs b/src/ImageSharp/Formats/Ico/IcoConstants.cs
similarity index 95%
rename from src/ImageSharp/Formats/Icon/Ico/IcoConstants.cs
rename to src/ImageSharp/Formats/Ico/IcoConstants.cs
index 345711705..0b963a431 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoConstants.cs
+++ b/src/ImageSharp/Formats/Ico/IcoConstants.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+namespace SixLabors.ImageSharp.Formats.Ico;
 
 /// <summary>
 /// Defines constants relating to ICOs
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoDecoder.cs b/src/ImageSharp/Formats/Ico/IcoDecoder.cs
similarity index 96%
rename from src/ImageSharp/Formats/Icon/Ico/IcoDecoder.cs
rename to src/ImageSharp/Formats/Ico/IcoDecoder.cs
index 5d6137920..a0c8a3075 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoDecoder.cs
+++ b/src/ImageSharp/Formats/Ico/IcoDecoder.cs
@@ -3,7 +3,7 @@
 
 using SixLabors.ImageSharp.PixelFormats;
 
-namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+namespace SixLabors.ImageSharp.Formats.Ico;
 
 /// <summary>
 /// Decoder for generating an image out of a ico encoded stream.
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs b/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
similarity index 84%
rename from src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
rename to src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
index c7841ce39..859340fb4 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoDecoderCore.cs
+++ b/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
@@ -1,11 +1,10 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Formats.Icon;
 using SixLabors.ImageSharp.Metadata;
 
-// TODO: flatten namespace.
-// namespace SixLabors.ImageSharp.Formats.Ico;
-namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+namespace SixLabors.ImageSharp.Formats.Ico;
 
 internal sealed class IcoDecoderCore : IconDecoderCore
 {
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoFormat.cs b/src/ImageSharp/Formats/Ico/IcoFormat.cs
similarity index 95%
rename from src/ImageSharp/Formats/Icon/Ico/IcoFormat.cs
rename to src/ImageSharp/Formats/Ico/IcoFormat.cs
index 27b0525bf..5f89ab7f2 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoFormat.cs
+++ b/src/ImageSharp/Formats/Ico/IcoFormat.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+namespace SixLabors.ImageSharp.Formats.Ico;
 
 /// <summary>
 /// Registers the image encoders, decoders and mime type detectors for the ICO format.
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs b/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
similarity index 97%
rename from src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
rename to src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
index 82e3c1db3..2a275d1a1 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
@@ -1,7 +1,9 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+using SixLabors.ImageSharp.Formats.Icon;
+
+namespace SixLabors.ImageSharp.Formats.Ico;
 
 /// <summary>
 /// IcoFrameMetadata. TODO: Remove base class and merge into this class.
diff --git a/src/ImageSharp/Formats/Icon/Ico/IcoMetadata.cs b/src/ImageSharp/Formats/Ico/IcoMetadata.cs
similarity index 89%
rename from src/ImageSharp/Formats/Icon/Ico/IcoMetadata.cs
rename to src/ImageSharp/Formats/Ico/IcoMetadata.cs
index b227d0bd6..f165bf916 100644
--- a/src/ImageSharp/Formats/Icon/Ico/IcoMetadata.cs
+++ b/src/ImageSharp/Formats/Ico/IcoMetadata.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+namespace SixLabors.ImageSharp.Formats.Ico;
 
 /// <summary>
 /// Provides Ico specific metadata information for the image.
diff --git a/src/ImageSharp/Formats/Icon/Ico/MetadataExtensions.cs b/src/ImageSharp/Formats/Ico/MetadataExtensions.cs
similarity index 97%
rename from src/ImageSharp/Formats/Icon/Ico/MetadataExtensions.cs
rename to src/ImageSharp/Formats/Ico/MetadataExtensions.cs
index fb5b4afe7..ba21d0abc 100644
--- a/src/ImageSharp/Formats/Icon/Ico/MetadataExtensions.cs
+++ b/src/ImageSharp/Formats/Ico/MetadataExtensions.cs
@@ -4,7 +4,7 @@
 using System.Diagnostics.CodeAnalysis;
 using SixLabors.ImageSharp.Metadata;
 
-namespace SixLabors.ImageSharp.Formats.Icon.Ico;
+namespace SixLabors.ImageSharp.Formats.Ico;
 
 /// <summary>
 /// Extension methods for the <see cref="ImageMetadata"/> type.
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
index f78c04cdf..d1587d35b 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-using SixLabors.ImageSharp.Formats.Icon.Cur;
+using SixLabors.ImageSharp.Formats.Cur;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Cur;
 
@@ -19,8 +19,6 @@ public class CurDecoderTests
 
         image.DebugSaveMultiFrame(provider, extension: "png");
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
-
         // TODO: Assert metadata, frame count, etc
     }
 }
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
index 86f8b003b..56378653a 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-using SixLabors.ImageSharp.Formats.Icon.Ico;
+using SixLabors.ImageSharp.Formats.Ico;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Ico;
 

From 794b2a6433cad5183901bd22e0c08c26126f9110 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:13:58 +0800
Subject: [PATCH 12/28] Refactor IconImageFormatDetector.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 .../Formats/Icon/IconImageFormatDetector.cs   | 59 +++++++++++++++----
 1 file changed, 47 insertions(+), 12 deletions(-)

diff --git a/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs b/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
index aff8dfe0a..4fceef3b8 100644
--- a/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
+++ b/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
@@ -2,7 +2,6 @@
 // Licensed under the Six Labors Split License.
 
 using System.Diagnostics.CodeAnalysis;
-using System.Runtime.InteropServices;
 
 namespace SixLabors.ImageSharp.Formats.Icon;
 
@@ -12,22 +11,58 @@ namespace SixLabors.ImageSharp.Formats.Icon;
 public class IconImageFormatDetector : IImageFormatDetector
 {
     /// <inheritdoc/>
-    public int HeaderSize { get; } = 4;
+    public int HeaderSize { get; } = IconDir.Size + IconDirEntry.Size;
 
     /// <inheritdoc/>
     public bool TryDetectFormat(ReadOnlySpan<byte> header, [NotNullWhen(true)] out IImageFormat? format)
     {
-        switch (MemoryMarshal.Cast<byte, uint>(header)[0])
+        format = this.IsSupportedFileFormat(header) switch
         {
-            case Ico.IcoConstants.FileHeader:
-                format = Ico.IcoFormat.Instance;
-                return true;
-            case Cur.CurConstants.FileHeader:
-                format = Cur.CurFormat.Instance;
-                return true;
-            default:
-                format = default;
-                return false;
+            true => Ico.IcoFormat.Instance,
+            false => Cur.CurFormat.Instance,
+            null => default
+        };
+
+        return format is not null;
+    }
+
+    private bool? IsSupportedFileFormat(ReadOnlySpan<byte> header)
+    {
+        // There are no magic bytes in the first few bytes of a tga file,
+        // so we try to figure out if its a valid tga by checking for valid tga header bytes.
+        if (header.Length < this.HeaderSize)
+        {
+            return null;
+        }
+
+        IconDir dir = IconDir.Parse(header);
+        if (dir is not { Reserved: 0 } // Should be 0.
+            or not { Type: IconFileType.ICO or IconFileType.CUR } // Unknown Type.
+            or { Count: 0 }) // Should not be 0.
+        {
+            return null;
+        }
+
+        IconDirEntry entry = IconDirEntry.Parse(header[IconDir.Size..]);
+        if (entry is not { Reserved: 0 } // Should be 0.
+            or { BytesInRes: 0 } // Should not be 0.
+            || entry.ImageOffset < IconDir.Size + (dir.Count * IconDirEntry.Size))
+        {
+            return null;
+        }
+
+        if (dir.Type is IconFileType.ICO)
+        {
+            if (entry is not { BitCount: 1 or 4 or 8 or 16 or 24 or 32 } or not { Planes: 0 or 1 })
+            {
+                return null;
+            }
+
+            return true;
+        }
+        else
+        {
+            return false;
         }
     }
 }

From 746e742183e671d83c42219a69ff9ea578daeeb2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 14:32:56 +0800
Subject: [PATCH 13/28] Fixed errors and warnings

---
 src/ImageSharp/Formats/Cur/CurDecoderCore.cs  |  7 +------
 src/ImageSharp/Formats/Ico/IcoDecoderCore.cs  |  7 +------
 .../Formats/Icon/IconDecoderCore.cs           | 20 +++++++++----------
 src/ImageSharp/Formats/Icon/IconDir.cs        | 15 ++++----------
 4 files changed, 16 insertions(+), 33 deletions(-)

diff --git a/src/ImageSharp/Formats/Cur/CurDecoderCore.cs b/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
index 4c0224652..538f9a2c6 100644
--- a/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
+++ b/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
@@ -6,13 +6,8 @@ using SixLabors.ImageSharp.Metadata;
 
 namespace SixLabors.ImageSharp.Formats.Cur;
 
-internal sealed class CurDecoderCore : IconDecoderCore
+internal sealed class CurDecoderCore(DecoderOptions options) : IconDecoderCore(options)
 {
-    public CurDecoderCore(DecoderOptions options)
-        : base(options)
-    {
-    }
-
     protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, Bmp.BmpBitsPerPixel bitsPerPixel)
     {
         CurFrameMetadata curFrameMetadata = metadata.GetCurMetadata();
diff --git a/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs b/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
index 859340fb4..78cb0d961 100644
--- a/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
+++ b/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
@@ -6,13 +6,8 @@ using SixLabors.ImageSharp.Metadata;
 
 namespace SixLabors.ImageSharp.Formats.Ico;
 
-internal sealed class IcoDecoderCore : IconDecoderCore
+internal sealed class IcoDecoderCore(DecoderOptions options) : IconDecoderCore(options)
 {
-    public IcoDecoderCore(DecoderOptions options)
-        : base(options)
-    {
-    }
-
     protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, Bmp.BmpBitsPerPixel bitsPerPixel)
     {
         IcoFrameMetadata icoFrameMetadata = metadata.GetIcoMetadata();
diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index 6af9553cc..983d4c346 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.IO;
@@ -10,19 +9,17 @@ using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Icon;
 
-internal abstract class IconDecoderCore : IImageDecoderInternals
+internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderInternals
 {
     private IconDir fileHeader;
 
-    public IconDecoderCore(DecoderOptions options) => this.Options = options;
-
-    public DecoderOptions Options { get; }
+    public DecoderOptions Options { get; } = options;
 
     public Size Dimensions { get; private set; }
 
     protected IconDir FileHeader { get => this.fileHeader; private set => this.fileHeader = value; }
 
-    protected IconDirEntry[] Entries { get; private set; } = Array.Empty<IconDirEntry>();
+    protected IconDirEntry[] Entries { get; private set; } = [];
 
     public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken)
         where TPixel : unmanaged, IPixel<TPixel>
@@ -52,7 +49,7 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
             }
 
             // Reset the stream position.
-            stream.Seek(-PngConstants.HeaderBytes.Length, SeekOrigin.Current);
+            _ = stream.Seek(-PngConstants.HeaderBytes.Length, SeekOrigin.Current);
 
             bool isPng = flag.SequenceEqual(PngConstants.HeaderBytes);
 
@@ -86,7 +83,7 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
                 }
 
                 // Bmp does not contain frame specific metadata.
-                target.Metadata.SetFormatMetadata(PngFormat.Instance, target.Metadata.GetPngFrameMetadata());
+                target.Metadata.SetFormatMetadata(PngFormat.Instance, target.Metadata.GetPngMetadata());
             }
             else
             {
@@ -137,7 +134,7 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
             }
 
             // Reset the stream position.
-            stream.Seek(-PngConstants.HeaderBytes.Length, SeekOrigin.Current);
+            _ = stream.Seek(-PngConstants.HeaderBytes.Length, SeekOrigin.Current);
 
             bool isPng = flag.SequenceEqual(PngConstants.HeaderBytes);
 
@@ -210,7 +207,10 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
     {
         if (isPng)
         {
-            return new PngDecoderCore(this.Options);
+            return new PngDecoderCore(new()
+            {
+                GeneralOptions = this.Options,
+            });
         }
         else
         {
diff --git a/src/ImageSharp/Formats/Icon/IconDir.cs b/src/ImageSharp/Formats/Icon/IconDir.cs
index 53b87bc9f..390a4de65 100644
--- a/src/ImageSharp/Formats/Icon/IconDir.cs
+++ b/src/ImageSharp/Formats/Icon/IconDir.cs
@@ -6,12 +6,12 @@ using System.Runtime.InteropServices;
 namespace SixLabors.ImageSharp.Formats.Icon;
 
 [StructLayout(LayoutKind.Sequential, Pack = 1, Size = Size)]
-internal struct IconDir
+internal struct IconDir(ushort reserved, IconFileType type, ushort count)
 {
     public const int Size = 3 * sizeof(ushort);
-    public ushort Reserved;
-    public IconFileType Type;
-    public ushort Count;
+    public ushort Reserved = reserved;
+    public IconFileType Type = type;
+    public ushort Count = count;
 
     public IconDir(IconFileType type)
         : this(type, 0)
@@ -23,13 +23,6 @@ internal struct IconDir
     {
     }
 
-    public IconDir(ushort reserved, IconFileType type, ushort count)
-    {
-        this.Reserved = reserved;
-        this.Type = type;
-        this.Count = count;
-    }
-
     public static IconDir Parse(in ReadOnlySpan<byte> data)
         => MemoryMarshal.Cast<byte, IconDir>(data)[0];
 }

From dbd178392f21d3cf36d2bb2129193453acb58fb9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 17:34:38 +0800
Subject: [PATCH 14/28] Add encoders that cannot be used.

---
 src/ImageSharp/Formats/Bmp/BmpEncoder.cs      |  9 +++
 src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs  | 81 ++++++++++++++++++-
 .../Formats/Cur/CurConfigurationModule.cs     |  3 +-
 src/ImageSharp/Formats/Cur/CurEncoder.cs      | 17 ++++
 src/ImageSharp/Formats/Cur/CurEncoderCore.cs  | 19 +++++
 .../Formats/Ico/IcoConfigurationModule.cs     |  3 +-
 src/ImageSharp/Formats/Ico/IcoEncoder.cs      | 17 ++++
 src/ImageSharp/Formats/Ico/IcoEncoderCore.cs  | 19 +++++
 src/ImageSharp/Formats/Icon/IconAssert.cs     | 14 ++++
 src/ImageSharp/Formats/Icon/IconDir.cs        |  3 +
 src/ImageSharp/Formats/Icon/IconDirEntry.cs   |  3 +
 .../Formats/Icon/IconEncoderCore.cs           | 69 ++++++++++++++++
 src/ImageSharp/Metadata/ImageMetadata.cs      |  1 +
 .../Formats/Icon/Cur/CurEncoderTests.cs       | 32 ++++++++
 .../Formats/Icon/Ico/IcoEncoderTests.cs       | 32 ++++++++
 15 files changed, 316 insertions(+), 6 deletions(-)
 create mode 100644 src/ImageSharp/Formats/Cur/CurEncoder.cs
 create mode 100644 src/ImageSharp/Formats/Cur/CurEncoderCore.cs
 create mode 100644 src/ImageSharp/Formats/Ico/IcoEncoder.cs
 create mode 100644 src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
 create mode 100644 src/ImageSharp/Formats/Icon/IconEncoderCore.cs
 create mode 100644 tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
 create mode 100644 tests/ImageSharp.Tests/Formats/Icon/Ico/IcoEncoderTests.cs

diff --git a/src/ImageSharp/Formats/Bmp/BmpEncoder.cs b/src/ImageSharp/Formats/Bmp/BmpEncoder.cs
index 0081f6a1a..0be243f9a 100644
--- a/src/ImageSharp/Formats/Bmp/BmpEncoder.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpEncoder.cs
@@ -29,6 +29,15 @@ public sealed class BmpEncoder : QuantizingImageEncoder
     /// </summary>
     public bool SupportTransparency { get; init; }
 
+    /// <inheritdoc cref="BmpDecoderOptions.ProcessedAlphaMask"/>
+    internal bool ProcessedAlphaMask { get; init; }
+
+    /// <inheritdoc cref="BmpDecoderOptions.SkipFileHeader"/>
+    internal bool SkipFileHeader { get; init; }
+
+    /// <inheritdoc cref="BmpDecoderOptions.UseDoubleHeight"/>
+    internal bool UseDoubleHeight { get; init; }
+
     /// <inheritdoc/>
     protected override void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
     {
diff --git a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
index 076d1adf0..b888fa400 100644
--- a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
@@ -3,6 +3,7 @@
 
 using System.Buffers;
 using System.Buffers.Binary;
+using System.IO;
 using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Common.Helpers;
@@ -11,6 +12,7 @@ using SixLabors.ImageSharp.Metadata;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Processing.Processors.Quantization;
+using static System.Net.Mime.MediaTypeNames;
 
 namespace SixLabors.ImageSharp.Formats.Bmp;
 
@@ -92,6 +94,15 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
     /// </summary>
     private readonly IPixelSamplingStrategy pixelSamplingStrategy;
 
+    /// <inheritdoc cref="BmpDecoderOptions.ProcessedAlphaMask"/>
+    private readonly bool processedAlphaMask;
+
+    /// <inheritdoc cref="BmpDecoderOptions.SkipFileHeader"/>
+    private readonly bool skipFileHeader;
+
+    /// <inheritdoc cref="BmpDecoderOptions.UseDoubleHeight"/>
+    private readonly bool isDoubleHeight;
+
     /// <summary>
     /// Initializes a new instance of the <see cref="BmpEncoderCore"/> class.
     /// </summary>
@@ -104,6 +115,9 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
         this.quantizer = encoder.Quantizer ?? KnownQuantizers.Octree;
         this.pixelSamplingStrategy = encoder.PixelSamplingStrategy;
         this.infoHeaderType = encoder.SupportTransparency ? BmpInfoHeaderType.WinVersion4 : BmpInfoHeaderType.WinVersion3;
+        this.processedAlphaMask = encoder.ProcessedAlphaMask;
+        this.skipFileHeader = encoder.SkipFileHeader;
+        this.isDoubleHeight = encoder.UseDoubleHeight;
     }
 
     /// <summary>
@@ -154,11 +168,23 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
             _ => BmpInfoHeader.SizeV3
         };
 
-        BmpInfoHeader infoHeader = this.CreateBmpInfoHeader(image.Width, image.Height, infoHeaderSize, bpp, bytesPerLine, metadata, iccProfileData);
+        // for ico/cur encoder.
+        int height = image.Height;
+        if (this.isDoubleHeight)
+        {
+            height <<= 1;
+        }
+
+        BmpInfoHeader infoHeader = this.CreateBmpInfoHeader(image.Width, height, infoHeaderSize, bpp, bytesPerLine, metadata, iccProfileData);
 
         Span<byte> buffer = stackalloc byte[infoHeaderSize];
 
-        WriteBitmapFileHeader(stream, infoHeaderSize, colorPaletteSize, iccProfileSize, infoHeader, buffer);
+        // for ico/cur encoder.
+        if (!this.skipFileHeader)
+        {
+            WriteBitmapFileHeader(stream, infoHeaderSize, colorPaletteSize, iccProfileSize, infoHeader, buffer);
+        }
+
         this.WriteBitmapInfoHeader(stream, infoHeader, buffer, infoHeaderSize);
         this.WriteImage(configuration, stream, image);
         WriteColorProfile(stream, iccProfileData, buffer);
@@ -455,6 +481,11 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
         {
             this.Write8BitColor(configuration, stream, image, colorPalette);
         }
+
+        if (this.processedAlphaMask)
+        {
+            ProcessedAlphaMask(stream, image);
+        }
     }
 
     /// <summary>
@@ -572,6 +603,11 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
                 stream.WriteByte(0);
             }
         }
+
+        if (this.processedAlphaMask)
+        {
+            ProcessedAlphaMask(stream, image);
+        }
     }
 
     /// <summary>
@@ -629,6 +665,11 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
                 stream.WriteByte(0);
             }
         }
+
+        if (this.processedAlphaMask)
+        {
+            ProcessedAlphaMask(stream, image);
+        }
     }
 
     /// <summary>
@@ -679,6 +720,11 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
                 stream.WriteByte(0);
             }
         }
+
+        if (this.processedAlphaMask)
+        {
+            ProcessedAlphaMask(stream, image);
+        }
     }
 
     /// <summary>
@@ -722,4 +768,35 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
 
         stream.WriteByte(indices);
     }
+
+    private static void ProcessedAlphaMask<TPixel>(Stream stream, Image<TPixel> image)
+         where TPixel : unmanaged, IPixel<TPixel>
+    {
+        Rgba32 rgba = default;
+        int arrayWidth = image.Width / 8;
+        int padding = arrayWidth % 4;
+        if (padding is not 0)
+        {
+            padding = 4 - padding;
+        }
+
+        Span<byte> mask = stackalloc byte[arrayWidth];
+        for (int y = image.Height - 1; y >= 0; y--)
+        {
+            mask.Clear();
+            for (int x = 0; x < image.Width; x++)
+            {
+                int bit = x % 8;
+                int i = x / 8;
+                TPixel pixel = image[x, y];
+                pixel.ToRgba32(ref rgba);
+                if (rgba.A is not 0)
+                {
+                    mask[i] &= unchecked((byte)(0b10000000 >> bit));
+                }
+            }
+
+            stream.Write(mask);
+        }
+    }
 }
diff --git a/src/ImageSharp/Formats/Cur/CurConfigurationModule.cs b/src/ImageSharp/Formats/Cur/CurConfigurationModule.cs
index 1c7db4bab..879b3f112 100644
--- a/src/ImageSharp/Formats/Cur/CurConfigurationModule.cs
+++ b/src/ImageSharp/Formats/Cur/CurConfigurationModule.cs
@@ -13,8 +13,7 @@ public sealed class CurConfigurationModule : IImageFormatConfigurationModule
     /// <inheritdoc/>
     public void Configure(Configuration configuration)
     {
-        // TODO: CurEncoder
-        // configuration.ImageFormatsManager.SetEncoder(CurFormat.Instance, new CurEncoder());
+        configuration.ImageFormatsManager.SetEncoder(CurFormat.Instance, new CurEncoder());
         configuration.ImageFormatsManager.SetDecoder(CurFormat.Instance, CurDecoder.Instance);
         configuration.ImageFormatsManager.AddImageFormatDetector(new IconImageFormatDetector());
     }
diff --git a/src/ImageSharp/Formats/Cur/CurEncoder.cs b/src/ImageSharp/Formats/Cur/CurEncoder.cs
new file mode 100644
index 000000000..d237fe7d0
--- /dev/null
+++ b/src/ImageSharp/Formats/Cur/CurEncoder.cs
@@ -0,0 +1,17 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Cur;
+
+/// <summary>
+/// Image encoder for writing an image to a stream as a Windows Cursor.
+/// </summary>
+public sealed class CurEncoder : QuantizingImageEncoder
+{
+    /// <inheritdoc/>
+    protected override void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
+    {
+        CurEncoderCore encoderCore = new();
+        encoderCore.Encode(image, stream, cancellationToken);
+    }
+}
diff --git a/src/ImageSharp/Formats/Cur/CurEncoderCore.cs b/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
new file mode 100644
index 000000000..0cf8c97a5
--- /dev/null
+++ b/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
@@ -0,0 +1,19 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Formats.Icon;
+
+namespace SixLabors.ImageSharp.Formats.Cur;
+
+internal sealed class CurEncoderCore : IconEncoderCore
+{
+    protected override void GetHeader(in Image image)
+    {
+        this.FileHeader = new(IconFileType.ICO, (ushort)image.Frames.Count);
+        this.Entries = image.Frames.Select(i =>
+        {
+            CurFrameMetadata metadata = i.Metadata.GetCurMetadata();
+            return metadata.ToIconDirEntry();
+        }).ToArray();
+    }
+}
diff --git a/src/ImageSharp/Formats/Ico/IcoConfigurationModule.cs b/src/ImageSharp/Formats/Ico/IcoConfigurationModule.cs
index b27d91465..224aaa31e 100644
--- a/src/ImageSharp/Formats/Ico/IcoConfigurationModule.cs
+++ b/src/ImageSharp/Formats/Ico/IcoConfigurationModule.cs
@@ -13,8 +13,7 @@ public sealed class IcoConfigurationModule : IImageFormatConfigurationModule
     /// <inheritdoc/>
     public void Configure(Configuration configuration)
     {
-        // TODO: IcoEncoder
-        // configuration.ImageFormatsManager.SetEncoder(IcoFormat.Instance, new IcoEncoder());
+        configuration.ImageFormatsManager.SetEncoder(IcoFormat.Instance, new IcoEncoder());
         configuration.ImageFormatsManager.SetDecoder(IcoFormat.Instance, IcoDecoder.Instance);
         configuration.ImageFormatsManager.AddImageFormatDetector(new IconImageFormatDetector());
     }
diff --git a/src/ImageSharp/Formats/Ico/IcoEncoder.cs b/src/ImageSharp/Formats/Ico/IcoEncoder.cs
new file mode 100644
index 000000000..0668a7e23
--- /dev/null
+++ b/src/ImageSharp/Formats/Ico/IcoEncoder.cs
@@ -0,0 +1,17 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Ico;
+
+/// <summary>
+/// Image encoder for writing an image to a stream as a Windows Icon.
+/// </summary>
+public sealed class IcoEncoder : QuantizingImageEncoder
+{
+    /// <inheritdoc/>
+    protected override void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
+    {
+        IcoEncoderCore encoderCore = new();
+        encoderCore.Encode(image, stream, cancellationToken);
+    }
+}
diff --git a/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs b/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
new file mode 100644
index 000000000..6c2f3abe4
--- /dev/null
+++ b/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
@@ -0,0 +1,19 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Formats.Icon;
+
+namespace SixLabors.ImageSharp.Formats.Ico;
+
+internal sealed class IcoEncoderCore : IconEncoderCore
+{
+    protected override void GetHeader(in Image image)
+    {
+        this.FileHeader = new(IconFileType.ICO, (ushort)image.Frames.Count);
+        this.Entries = image.Frames.Select(i =>
+        {
+            IcoFrameMetadata metadata = i.Metadata.GetIcoMetadata();
+            return metadata.ToIconDirEntry();
+        }).ToArray();
+    }
+}
diff --git a/src/ImageSharp/Formats/Icon/IconAssert.cs b/src/ImageSharp/Formats/Icon/IconAssert.cs
index 04a9527b9..547b6a6eb 100644
--- a/src/ImageSharp/Formats/Icon/IconAssert.cs
+++ b/src/ImageSharp/Formats/Icon/IconAssert.cs
@@ -32,4 +32,18 @@ internal class IconAssert
 
         return v;
     }
+
+    internal static byte Is1ByteSize(int i)
+    {
+        if (i is 256)
+        {
+            return 0;
+        }
+        else if (i > byte.MaxValue)
+        {
+            throw new FormatException("Image size Too Large.");
+        }
+
+        return (byte)i;
+    }
 }
diff --git a/src/ImageSharp/Formats/Icon/IconDir.cs b/src/ImageSharp/Formats/Icon/IconDir.cs
index 390a4de65..aa583ee1e 100644
--- a/src/ImageSharp/Formats/Icon/IconDir.cs
+++ b/src/ImageSharp/Formats/Icon/IconDir.cs
@@ -25,4 +25,7 @@ internal struct IconDir(ushort reserved, IconFileType type, ushort count)
 
     public static IconDir Parse(in ReadOnlySpan<byte> data)
         => MemoryMarshal.Cast<byte, IconDir>(data)[0];
+
+    public unsafe void WriteTo(in Stream stream)
+        => stream.Write(MemoryMarshal.Cast<IconDir, byte>([this]));
 }
diff --git a/src/ImageSharp/Formats/Icon/IconDirEntry.cs b/src/ImageSharp/Formats/Icon/IconDirEntry.cs
index edd778f7e..7a8e09e37 100644
--- a/src/ImageSharp/Formats/Icon/IconDirEntry.cs
+++ b/src/ImageSharp/Formats/Icon/IconDirEntry.cs
@@ -28,4 +28,7 @@ internal struct IconDirEntry
 
     public static IconDirEntry Parse(in ReadOnlySpan<byte> data)
         => MemoryMarshal.Cast<byte, IconDirEntry>(data)[0];
+
+    public unsafe void WriteTo(in Stream stream)
+        => stream.Write(MemoryMarshal.Cast<IconDirEntry, byte>([this]));
 }
diff --git a/src/ImageSharp/Formats/Icon/IconEncoderCore.cs b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
new file mode 100644
index 000000000..05a657b51
--- /dev/null
+++ b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
@@ -0,0 +1,69 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Diagnostics.CodeAnalysis;
+using SixLabors.ImageSharp.Formats.Bmp;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Icon;
+
+internal abstract class IconEncoderCore : IImageEncoderInternals
+{
+    protected IconDir FileHeader { get; set; }
+
+    protected IconDirEntry[]? Entries { get; set; }
+
+    public void Encode<TPixel>(
+        Image<TPixel> image,
+        Stream stream,
+        CancellationToken cancellationToken)
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        Guard.NotNull(image, nameof(image));
+        Guard.NotNull(stream, nameof(stream));
+
+        IconAssert.CanSeek(stream);
+
+        // Stream may not at 0.
+        long basePosition = stream.Position;
+        this.GetHeader(image);
+
+        int dataOffset = IconDir.Size + (IconDirEntry.Size * this.Entries.Length);
+        _ = stream.Seek(dataOffset, SeekOrigin.Current);
+
+        for (int i = 0; i < image.Frames.Count; i++)
+        {
+            ImageFrame<TPixel> frame = image.Frames[i];
+            this.Entries[i].ImageOffset = (uint)stream.Position;
+            Image<TPixel> img = new(Configuration.Default, frame.PixelBuffer, new());
+
+            // Note: this encoder are not supported PNG Data.
+            BmpEncoder encoder = new()
+            {
+                ProcessedAlphaMask = true,
+                UseDoubleHeight = true,
+                SkipFileHeader = true,
+                SupportTransparency = false,
+                BitsPerPixel = this.Entries[i].BitCount is 0
+                    ? BmpBitsPerPixel.Pixel8
+                    : (BmpBitsPerPixel?)this.Entries[i].BitCount
+            };
+
+            encoder.Encode(img, stream);
+            this.Entries[i].BytesInRes = this.Entries[i].ImageOffset - (uint)stream.Position;
+        }
+
+        long endPosition = stream.Position;
+        _ = stream.Seek(basePosition, SeekOrigin.Begin);
+        this.FileHeader.WriteTo(stream);
+        foreach (IconDirEntry entry in this.Entries)
+        {
+            entry.WriteTo(stream);
+        }
+
+        _ = stream.Seek(endPosition, SeekOrigin.Begin);
+    }
+
+    [MemberNotNull(nameof(Entries))]
+    protected abstract void GetHeader(in Image image);
+}
diff --git a/src/ImageSharp/Metadata/ImageMetadata.cs b/src/ImageSharp/Metadata/ImageMetadata.cs
index d9aba6631..e811cc1f7 100644
--- a/src/ImageSharp/Metadata/ImageMetadata.cs
+++ b/src/ImageSharp/Metadata/ImageMetadata.cs
@@ -215,6 +215,7 @@ public sealed class ImageMetadata : IDeepCloneable<ImageMetadata>
         metadata = default;
         return false;
     }
+
     internal void SetFormatMetadata<TFormatMetadata>(IImageFormat<TFormatMetadata> key, TFormatMetadata value)
         where TFormatMetadata : class, IDeepCloneable
         => this.formatMetadata[key] = value;
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
new file mode 100644
index 000000000..9908786f1
--- /dev/null
+++ b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
@@ -0,0 +1,32 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Formats.Cur;
+using SixLabors.ImageSharp.PixelFormats;
+using static SixLabors.ImageSharp.Tests.TestImages.Cur;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Icon.Cur;
+
+[Trait("Format", "Cur")]
+public class CurEncoderTests
+{
+    private static CurEncoder CurEncoder => new();
+
+    public static readonly TheoryData<string> Files = new()
+    {
+        { WindowsMouse },
+    };
+
+    [Theory]
+    [MemberData(nameof(Files))]
+    public void Encode(string imagePath)
+    {
+        TestFile testFile = TestFile.Create(imagePath);
+        using Image<Rgba32> input = testFile.CreateRgba32Image();
+        using MemoryStream memStream = new();
+        input.Save(memStream, CurEncoder);
+
+        memStream.Seek(0, SeekOrigin.Begin);
+        CurDecoder.Instance.Decode(new(), memStream);
+    }
+}
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoEncoderTests.cs
new file mode 100644
index 000000000..9a239bdd4
--- /dev/null
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoEncoderTests.cs
@@ -0,0 +1,32 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Formats.Ico;
+using SixLabors.ImageSharp.PixelFormats;
+using static SixLabors.ImageSharp.Tests.TestImages.Ico;
+
+namespace SixLabors.ImageSharp.Tests.Formats.Icon.Ico;
+
+[Trait("Format", "Icon")]
+public class IcoEncoderTests
+{
+    private static IcoEncoder CurEncoder => new();
+
+    public static readonly TheoryData<string> Files = new()
+    {
+        { Flutter },
+    };
+
+    [Theory]
+    [MemberData(nameof(Files))]
+    public void Encode(string imagePath)
+    {
+        TestFile testFile = TestFile.Create(imagePath);
+        using Image<Rgba32> input = testFile.CreateRgba32Image();
+        using MemoryStream memStream = new();
+        input.Save(memStream, CurEncoder);
+
+        memStream.Seek(0, SeekOrigin.Begin);
+        IcoDecoder.Instance.Decode(new(), memStream);
+    }
+}

From 54e87ab63ace1daa546f0476408fb84ab1557967 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 19:43:12 +0800
Subject: [PATCH 15/28] Remove a comment

---
 src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs b/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
index 4fceef3b8..b66b6c79f 100644
--- a/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
+++ b/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
@@ -38,7 +38,7 @@ public class IconImageFormatDetector : IImageFormatDetector
         IconDir dir = IconDir.Parse(header);
         if (dir is not { Reserved: 0 } // Should be 0.
             or not { Type: IconFileType.ICO or IconFileType.CUR } // Unknown Type.
-            or { Count: 0 }) // Should not be 0.
+            or { Count: 0 })
         {
             return null;
         }

From 21b1e71062915603e16792b88e5cb528d5444d02 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 21:47:27 +0800
Subject: [PATCH 16/28] Encoder Worked!

but AlphaMask have some problems
---
 src/ImageSharp/Formats/Cur/CurEncoderCore.cs  | 11 +--
 .../Formats/Cur/MetadataExtensions.cs         |  5 +-
 src/ImageSharp/Formats/Ico/IcoEncoderCore.cs  | 11 +--
 .../Formats/Ico/IcoFrameMetadata.cs           |  3 +-
 .../Formats/Ico/MetadataExtensions.cs         |  5 +-
 .../Formats/Icon/IconEncoderCore.cs           | 97 ++++++++++++++-----
 6 files changed, 84 insertions(+), 48 deletions(-)

diff --git a/src/ImageSharp/Formats/Cur/CurEncoderCore.cs b/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
index 0cf8c97a5..3a7288b71 100644
--- a/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
+++ b/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
@@ -5,15 +5,6 @@ using SixLabors.ImageSharp.Formats.Icon;
 
 namespace SixLabors.ImageSharp.Formats.Cur;
 
-internal sealed class CurEncoderCore : IconEncoderCore
+internal sealed class CurEncoderCore() : IconEncoderCore(IconFileType.CUR)
 {
-    protected override void GetHeader(in Image image)
-    {
-        this.FileHeader = new(IconFileType.ICO, (ushort)image.Frames.Count);
-        this.Entries = image.Frames.Select(i =>
-        {
-            CurFrameMetadata metadata = i.Metadata.GetCurMetadata();
-            return metadata.ToIconDirEntry();
-        }).ToArray();
-    }
 }
diff --git a/src/ImageSharp/Formats/Cur/MetadataExtensions.cs b/src/ImageSharp/Formats/Cur/MetadataExtensions.cs
index 2b410a0f9..6394c564b 100644
--- a/src/ImageSharp/Formats/Cur/MetadataExtensions.cs
+++ b/src/ImageSharp/Formats/Cur/MetadataExtensions.cs
@@ -2,14 +2,15 @@
 // Licensed under the Six Labors Split License.
 
 using System.Diagnostics.CodeAnalysis;
+using SixLabors.ImageSharp.Formats.Cur;
 using SixLabors.ImageSharp.Metadata;
 
-namespace SixLabors.ImageSharp.Formats.Cur;
+namespace SixLabors.ImageSharp;
 
 /// <summary>
 /// Extension methods for the <see cref="ImageMetadata"/> type.
 /// </summary>
-public static class MetadataExtensions
+public static partial class MetadataExtensions
 {
     /// <summary>
     /// Gets the Icon format specific metadata for the image.
diff --git a/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs b/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
index 6c2f3abe4..12ced58fd 100644
--- a/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
+++ b/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
@@ -5,15 +5,6 @@ using SixLabors.ImageSharp.Formats.Icon;
 
 namespace SixLabors.ImageSharp.Formats.Ico;
 
-internal sealed class IcoEncoderCore : IconEncoderCore
+internal sealed class IcoEncoderCore() : IconEncoderCore(IconFileType.ICO)
 {
-    protected override void GetHeader(in Image image)
-    {
-        this.FileHeader = new(IconFileType.ICO, (ushort)image.Frames.Count);
-        this.Entries = image.Frames.Select(i =>
-        {
-            IcoFrameMetadata metadata = i.Metadata.GetIcoMetadata();
-            return metadata.ToIconDirEntry();
-        }).ToArray();
-    }
 }
diff --git a/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs b/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
index 2a275d1a1..8d7eb17b5 100644
--- a/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
@@ -88,7 +88,8 @@ public class IcoFrameMetadata : IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
         BitCount = this.Compression switch
         {
             IconFrameCompression.Bmp => (ushort)this.BitsPerPixel,
-            _ => 0,
+            IconFrameCompression.Png => 32,
+            _ => throw new NotSupportedException($"Value: {this.Compression}"),
         },
     };
 }
diff --git a/src/ImageSharp/Formats/Ico/MetadataExtensions.cs b/src/ImageSharp/Formats/Ico/MetadataExtensions.cs
index ba21d0abc..497375f99 100644
--- a/src/ImageSharp/Formats/Ico/MetadataExtensions.cs
+++ b/src/ImageSharp/Formats/Ico/MetadataExtensions.cs
@@ -2,14 +2,15 @@
 // Licensed under the Six Labors Split License.
 
 using System.Diagnostics.CodeAnalysis;
+using SixLabors.ImageSharp.Formats.Ico;
 using SixLabors.ImageSharp.Metadata;
 
-namespace SixLabors.ImageSharp.Formats.Ico;
+namespace SixLabors.ImageSharp;
 
 /// <summary>
 /// Extension methods for the <see cref="ImageMetadata"/> type.
 /// </summary>
-public static class MetadataExtensions
+public static partial class MetadataExtensions
 {
     /// <summary>
     /// Gets the Ico format specific metadata for the image.
diff --git a/src/ImageSharp/Formats/Icon/IconEncoderCore.cs b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
index 05a657b51..b4d563d4b 100644
--- a/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
@@ -2,16 +2,18 @@
 // Licensed under the Six Labors Split License.
 
 using System.Diagnostics.CodeAnalysis;
-using SixLabors.ImageSharp.Formats.Bmp;
+using SixLabors.ImageSharp.Formats.Cur;
+using SixLabors.ImageSharp.Formats.Ico;
 using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Icon;
 
-internal abstract class IconEncoderCore : IImageEncoderInternals
+internal abstract class IconEncoderCore(IconFileType iconFileType)
+    : IImageEncoderInternals
 {
-    protected IconDir FileHeader { get; set; }
+    private IconDir fileHeader;
 
-    protected IconDirEntry[]? Entries { get; set; }
+    private IconFrameMetadata[]? entries;
 
     public void Encode<TPixel>(
         Image<TPixel> image,
@@ -26,44 +28,93 @@ internal abstract class IconEncoderCore : IImageEncoderInternals
 
         // Stream may not at 0.
         long basePosition = stream.Position;
-        this.GetHeader(image);
+        this.InitHeader(image);
 
-        int dataOffset = IconDir.Size + (IconDirEntry.Size * this.Entries.Length);
+        int dataOffset = IconDir.Size + (IconDirEntry.Size * this.entries.Length);
         _ = stream.Seek(dataOffset, SeekOrigin.Current);
 
         for (int i = 0; i < image.Frames.Count; i++)
         {
             ImageFrame<TPixel> frame = image.Frames[i];
-            this.Entries[i].ImageOffset = (uint)stream.Position;
-            Image<TPixel> img = new(Configuration.Default, frame.PixelBuffer, new());
+            int width = this.entries[i].Entry.Width;
+            if (width is 0)
+            {
+                width = frame.Width;
+            }
+
+            int height = this.entries[i].Entry.Height;
+            if (height is 0)
+            {
+                height = frame.Height;
+            }
+
+            this.entries[i].Entry.ImageOffset = (uint)stream.Position;
 
-            // Note: this encoder are not supported PNG Data.
-            BmpEncoder encoder = new()
+            Image<TPixel> img = new(width, height);
+            for (int y = 0; y < height; y++)
             {
-                ProcessedAlphaMask = true,
-                UseDoubleHeight = true,
-                SkipFileHeader = true,
-                SupportTransparency = false,
-                BitsPerPixel = this.Entries[i].BitCount is 0
-                    ? BmpBitsPerPixel.Pixel8
-                    : (BmpBitsPerPixel?)this.Entries[i].BitCount
+                frame.PixelBuffer.DangerousGetRowSpan(y)[..width].CopyTo(img.GetRootFramePixelBuffer().DangerousGetRowSpan(y));
+            }
+
+            QuantizingImageEncoder encoder = this.entries[i].Compression switch
+            {
+                IconFrameCompression.Bmp => new Bmp.BmpEncoder()
+                {
+                    ProcessedAlphaMask = true,
+                    UseDoubleHeight = true,
+                    SkipFileHeader = true,
+                    SupportTransparency = false,
+                    BitsPerPixel = iconFileType is IconFileType.ICO
+                        ? (Bmp.BmpBitsPerPixel?)this.entries[i].Entry.BitCount
+                        : Bmp.BmpBitsPerPixel.Pixel24 // TODO: Here you need to switch to selecting the corresponding value according to the size of the image
+                },
+                IconFrameCompression.Png => new Png.PngEncoder(),
+                _ => throw new NotSupportedException(),
             };
 
             encoder.Encode(img, stream);
-            this.Entries[i].BytesInRes = this.Entries[i].ImageOffset - (uint)stream.Position;
+            this.entries[i].Entry.BytesInRes = (uint)stream.Position - this.entries[i].Entry.ImageOffset;
         }
 
         long endPosition = stream.Position;
         _ = stream.Seek(basePosition, SeekOrigin.Begin);
-        this.FileHeader.WriteTo(stream);
-        foreach (IconDirEntry entry in this.Entries)
+        this.fileHeader.WriteTo(stream);
+        foreach (IconFrameMetadata frame in this.entries)
         {
-            entry.WriteTo(stream);
+            frame.Entry.WriteTo(stream);
         }
 
         _ = stream.Seek(endPosition, SeekOrigin.Begin);
     }
 
-    [MemberNotNull(nameof(Entries))]
-    protected abstract void GetHeader(in Image image);
+    [MemberNotNull(nameof(entries))]
+    private void InitHeader(in Image image)
+    {
+        this.fileHeader = new(iconFileType, (ushort)image.Frames.Count);
+        this.entries = iconFileType switch
+        {
+            IconFileType.ICO =>
+            image.Frames.Select(i =>
+            {
+                IcoFrameMetadata metadata = i.Metadata.GetIcoMetadata();
+                return new IconFrameMetadata(metadata.Compression, metadata.ToIconDirEntry());
+            }).ToArray(),
+            IconFileType.CUR =>
+            image.Frames.Select(i =>
+            {
+                CurFrameMetadata metadata = i.Metadata.GetCurMetadata();
+                return new IconFrameMetadata(metadata.Compression, metadata.ToIconDirEntry());
+            }).ToArray(),
+            _ => throw new NotSupportedException(),
+        };
+    }
+
+    internal sealed class IconFrameMetadata(IconFrameCompression compression, IconDirEntry iconDirEntry)
+    {
+        private IconDirEntry iconDirEntry = iconDirEntry;
+
+        public IconFrameCompression Compression { get; set; } = compression;
+
+        public ref IconDirEntry Entry => ref this.iconDirEntry;
+    }
 }

From e252a6f223120357fe00cc9c3aa842d250b131ad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 21:48:34 +0800
Subject: [PATCH 17/28] Using Seek requires consideration of whether this
 stream allows Seek and the case where the stream start position is not 0.

---
 src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
index b888fa400..dcccc8363 100644
--- a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
@@ -133,6 +133,9 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
         Guard.NotNull(image, nameof(image));
         Guard.NotNull(stream, nameof(stream));
 
+        // Stream may not at 0.
+        long basePosition = stream.Position;
+
         Configuration configuration = image.Configuration;
         ImageMetadata metadata = image.Metadata;
         BmpMetadata bmpMetadata = metadata.GetBmpMetadata();
@@ -187,7 +190,7 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
 
         this.WriteBitmapInfoHeader(stream, infoHeader, buffer, infoHeaderSize);
         this.WriteImage(configuration, stream, image);
-        WriteColorProfile(stream, iccProfileData, buffer);
+        WriteColorProfile(stream, iccProfileData, buffer, basePosition);
 
         stream.Flush();
     }
@@ -271,16 +274,20 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
     /// <param name="stream">The stream to write to.</param>
     /// <param name="iccProfileData">The color profile data.</param>
     /// <param name="buffer">The buffer.</param>
-    private static void WriteColorProfile(Stream stream, byte[]? iccProfileData, Span<byte> buffer)
+    /// <param name="basePosition">The Stream may not be start with 0.</param>
+    private static void WriteColorProfile(Stream stream, byte[]? iccProfileData, Span<byte> buffer, long basePosition)
     {
         if (iccProfileData != null)
         {
             // The offset, in bytes, from the beginning of the BITMAPV5HEADER structure to the start of the profile data.
             int streamPositionAfterImageData = (int)stream.Position - BmpFileHeader.Size;
             stream.Write(iccProfileData);
+            long position = stream.Position; // Storage Position
             BinaryPrimitives.WriteInt32LittleEndian(buffer, streamPositionAfterImageData);
-            stream.Position = BmpFileHeader.Size + 112;
+            _ = stream.Seek(basePosition, SeekOrigin.Begin);
+            _ = stream.Seek(BmpFileHeader.Size + 112, SeekOrigin.Current);
             stream.Write(buffer[..4]);
+            _ = stream.Seek(position, SeekOrigin.Begin); // Reset Position
         }
     }
 

From fae15ae88aa1b8131076159b199f51c1d32ac70e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 22:51:52 +0800
Subject: [PATCH 18/28] Fixed AlphaMask

---
 src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs | 55 +++++++++-----------
 1 file changed, 24 insertions(+), 31 deletions(-)

diff --git a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
index dcccc8363..fe1c9e0be 100644
--- a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
@@ -3,16 +3,13 @@
 
 using System.Buffers;
 using System.Buffers.Binary;
-using System.IO;
 using System.Runtime.InteropServices;
-using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Common.Helpers;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.Metadata;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Processing.Processors.Quantization;
-using static System.Net.Mime.MediaTypeNames;
 
 namespace SixLabors.ImageSharp.Formats.Bmp;
 
@@ -380,6 +377,11 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
                 this.Write1BitPixelData(configuration, stream, image);
                 break;
         }
+
+        if (this.processedAlphaMask)
+        {
+            ProcessedAlphaMask(stream, image);
+        }
     }
 
     private IMemoryOwner<byte> AllocateRow(int width, int bytesPerPixel)
@@ -488,11 +490,6 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
         {
             this.Write8BitColor(configuration, stream, image, colorPalette);
         }
-
-        if (this.processedAlphaMask)
-        {
-            ProcessedAlphaMask(stream, image);
-        }
     }
 
     /// <summary>
@@ -610,11 +607,6 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
                 stream.WriteByte(0);
             }
         }
-
-        if (this.processedAlphaMask)
-        {
-            ProcessedAlphaMask(stream, image);
-        }
     }
 
     /// <summary>
@@ -672,11 +664,6 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
                 stream.WriteByte(0);
             }
         }
-
-        if (this.processedAlphaMask)
-        {
-            ProcessedAlphaMask(stream, image);
-        }
     }
 
     /// <summary>
@@ -727,11 +714,6 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
                 stream.WriteByte(0);
             }
         }
-
-        if (this.processedAlphaMask)
-        {
-            ProcessedAlphaMask(stream, image);
-        }
     }
 
     /// <summary>
@@ -779,7 +761,6 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
     private static void ProcessedAlphaMask<TPixel>(Stream stream, Image<TPixel> image)
          where TPixel : unmanaged, IPixel<TPixel>
     {
-        Rgba32 rgba = default;
         int arrayWidth = image.Width / 8;
         int padding = arrayWidth % 4;
         if (padding is not 0)
@@ -791,19 +772,31 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
         for (int y = image.Height - 1; y >= 0; y--)
         {
             mask.Clear();
-            for (int x = 0; x < image.Width; x++)
+            Span<TPixel> row = image.GetRootFramePixelBuffer().DangerousGetRowSpan(y);
+
+            for (int i = 0; i < arrayWidth; i++)
             {
-                int bit = x % 8;
-                int i = x / 8;
-                TPixel pixel = image[x, y];
-                pixel.ToRgba32(ref rgba);
-                if (rgba.A is not 0)
+                int x = i * 8;
+
+                for (int j = 0; j < 8; j++)
                 {
-                    mask[i] &= unchecked((byte)(0b10000000 >> bit));
+                    WriteAlphaMask(row[x + j], ref mask[i], j);
                 }
             }
 
             stream.Write(mask);
+            stream.Skip(padding);
+        }
+    }
+
+    private static void WriteAlphaMask<TPixel>(in TPixel pixel, ref byte mask, in int index)
+         where TPixel : unmanaged, IPixel<TPixel>
+    {
+        Rgba32 rgba = default;
+        pixel.ToRgba32(ref rgba);
+        if (rgba.A is 0)
+        {
+            mask |= unchecked((byte)(0b10000000 >> index));
         }
     }
 }

From 52f392db568bf27cbe127ae1812f6d05a9ab7df2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Thu, 14 Dec 2023 22:58:15 +0800
Subject: [PATCH 19/28] Fixed some warnings.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 .../Formats/Icon/IconDecoderCore.cs           | 29 +++++++++----------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index 983d4c346..a502b91c9 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.Diagnostics.CodeAnalysis;
 using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.IO;
@@ -12,15 +13,12 @@ namespace SixLabors.ImageSharp.Formats.Icon;
 internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderInternals
 {
     private IconDir fileHeader;
+    private IconDirEntry[]? entries;
 
     public DecoderOptions Options { get; } = options;
 
     public Size Dimensions { get; private set; }
 
-    protected IconDir FileHeader { get => this.fileHeader; private set => this.fileHeader = value; }
-
-    protected IconDirEntry[] Entries { get; private set; } = [];
-
     public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken)
         where TPixel : unmanaged, IPixel<TPixel>
     {
@@ -30,11 +28,11 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
 
         Span<byte> flag = stackalloc byte[PngConstants.HeaderBytes.Length];
 
-        List<(Image<TPixel> Image, IconFrameCompression Compression, int Index)> decodedEntries = new(this.Entries.Length);
+        List<(Image<TPixel> Image, IconFrameCompression Compression, int Index)> decodedEntries = new(this.entries.Length);
 
-        for (int i = 0; i < this.Entries.Length; i++)
+        for (int i = 0; i < this.entries.Length; i++)
         {
-            ref IconDirEntry entry = ref this.Entries[i];
+            ref IconDirEntry entry = ref this.entries[i];
 
             // If we hit the end of the stream we should break.
             if (stream.Seek(basePosition + entry.ImageOffset, SeekOrigin.Begin) >= stream.Length)
@@ -90,7 +88,7 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
                 bitsPerPixel = x.Image.Metadata.GetBmpMetadata().BitsPerPixel;
             }
 
-            this.SetFrameMetadata(target.Metadata, this.Entries[x.Index], x.Compression, bitsPerPixel);
+            this.SetFrameMetadata(target.Metadata, this.entries[x.Index], x.Compression, bitsPerPixel);
 
             x.Image.Dispose();
 
@@ -115,11 +113,11 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
         Span<byte> flag = stackalloc byte[PngConstants.HeaderBytes.Length];
 
         ImageMetadata metadata = new();
-        ImageFrameMetadata[] frames = new ImageFrameMetadata[this.FileHeader.Count];
+        ImageFrameMetadata[] frames = new ImageFrameMetadata[this.fileHeader.Count];
         for (int i = 0; i < frames.Length; i++)
         {
             BmpBitsPerPixel bitsPerPixel = default;
-            ref IconDirEntry entry = ref this.Entries[i];
+            ref IconDirEntry entry = ref this.entries[i];
 
             // If we hit the end of the stream we should break.
             if (stream.Seek(basePosition + entry.ImageOffset, SeekOrigin.Begin) >= stream.Length)
@@ -147,7 +145,7 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
                 bitsPerPixel = temp.Metadata.GetBmpMetadata().BitsPerPixel;
             }
 
-            this.SetFrameMetadata(frames[i], this.Entries[i], isPng ? IconFrameCompression.Png : IconFrameCompression.Bmp, bitsPerPixel);
+            this.SetFrameMetadata(frames[i], this.entries[i], isPng ? IconFrameCompression.Png : IconFrameCompression.Bmp, bitsPerPixel);
 
             // Since Windows Vista, the size of an image is determined from the BITMAPINFOHEADER structure or PNG image data
             // which technically allows storing icons with larger than 256 pixels, but such larger sizes are not recommended by Microsoft.
@@ -159,6 +157,7 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
 
     protected abstract void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, BmpBitsPerPixel bitsPerPixel);
 
+    [MemberNotNull(nameof(entries))]
     protected void ReadHeader(Stream stream)
     {
         Span<byte> buffer = stackalloc byte[IconDirEntry.Size];
@@ -168,16 +167,16 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
         this.fileHeader = IconDir.Parse(buffer);
 
         // ICONDIRENTRY
-        this.Entries = new IconDirEntry[this.FileHeader.Count];
-        for (int i = 0; i < this.Entries.Length; i++)
+        this.entries = new IconDirEntry[this.fileHeader.Count];
+        for (int i = 0; i < this.entries.Length; i++)
         {
             _ = IconAssert.EndOfStream(stream.Read(buffer[..IconDirEntry.Size]), IconDirEntry.Size);
-            this.Entries[i] = IconDirEntry.Parse(buffer);
+            this.entries[i] = IconDirEntry.Parse(buffer);
         }
 
         int width = 0;
         int height = 0;
-        foreach (IconDirEntry entry in this.Entries)
+        foreach (IconDirEntry entry in this.entries)
         {
             // Since Windows 95 size of an image in the ICONDIRENTRY structure might
             // be set to zero, which means 256 pixels.

From 5be5d64882e5e85fed199cbc621bcd16734b008b Mon Sep 17 00:00:00 2001
From: Poker <poker_sang@outlook.com>
Date: Thu, 14 Mar 2024 12:17:44 +0800
Subject: [PATCH 20/28] fix

---
 src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs | 4 ++--
 src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs | 3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
index 568eea00a..11c6aef29 100644
--- a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
@@ -898,7 +898,7 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
                     {
                         int colorIndex = ((rowSpan[offset] >> (8 - bitsPerPixel - (shift * bitsPerPixel))) & mask) * bytesPerColorMapEntry;
 
-                        image[newY, newX].FromBgr24(Unsafe.As<byte, Bgr24>(ref colors[colorIndex]));
+                        image[newY, newX] = Bgra32.FromBgr24(Unsafe.As<byte, Bgr24>(ref colors[colorIndex]));
                     }
 
                     offset++;
@@ -942,7 +942,7 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
 
             for (int x = 0; x < width; x++)
             {
-                pixelRow[x].FromBgra32(image[newY, x]);
+                pixelRow[x] = TPixel.FromBgra32(image[newY, x]);
             }
         }
     }
diff --git a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
index fe1c9e0be..f84e4f9c2 100644
--- a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
@@ -792,8 +792,7 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
     private static void WriteAlphaMask<TPixel>(in TPixel pixel, ref byte mask, in int index)
          where TPixel : unmanaged, IPixel<TPixel>
     {
-        Rgba32 rgba = default;
-        pixel.ToRgba32(ref rgba);
+        Rgba32 rgba = pixel.ToRgba32();
         if (rgba.A is 0)
         {
             mask |= unchecked((byte)(0b10000000 >> index));

From 6beeba1575ed58dbde57332714c639a2d1451611 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Tue, 18 Jun 2024 21:41:08 +1000
Subject: [PATCH 21/28] Cleanup and fix issues

---
 src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs  |  9 ++
 src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs  |  2 +
 src/ImageSharp/Formats/Bmp/BmpMetadata.cs     | 14 +++-
 src/ImageSharp/Formats/Cur/CurConstants.cs    | 25 ++++--
 src/ImageSharp/Formats/Cur/CurDecoderCore.cs  | 12 ++-
 src/ImageSharp/Formats/Cur/CurEncoderCore.cs  |  6 +-
 .../Formats/Cur/CurFrameMetadata.cs           | 83 ++++++++-----------
 src/ImageSharp/Formats/Ico/IcoConstants.cs    | 11 +--
 src/ImageSharp/Formats/Ico/IcoDecoderCore.cs  | 12 ++-
 src/ImageSharp/Formats/Ico/IcoEncoder.cs      |  4 +-
 src/ImageSharp/Formats/Ico/IcoEncoderCore.cs  |  6 +-
 .../Formats/Ico/IcoFrameMetadata.cs           | 76 +++++++----------
 src/ImageSharp/Formats/Icon/IconAssert.cs     | 32 -------
 .../Formats/Icon/IconDecoderCore.cs           | 44 ++++++----
 src/ImageSharp/Formats/Icon/IconDir.cs        | 16 +++-
 src/ImageSharp/Formats/Icon/IconDirEntry.cs   | 28 ++++++-
 .../Formats/Icon/IconEncoderCore.cs           | 73 +++++++++++-----
 .../Formats/Icon/IconImageFormatDetector.cs   |  6 +-
 18 files changed, 263 insertions(+), 196 deletions(-)

diff --git a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
index 11c6aef29..c26536fd1 100644
--- a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
@@ -6,6 +6,7 @@ using System.Buffers.Binary;
 using System.Diagnostics.CodeAnalysis;
 using System.Numerics;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Common.Helpers;
 using SixLabors.ImageSharp.IO;
 using SixLabors.ImageSharp.Memory;
@@ -1599,6 +1600,14 @@ internal sealed class BmpDecoderCore : IImageDecoderInternals
             }
         }
 
+        if (palette.Length > 0)
+        {
+            Color[] colorTable = new Color[palette.Length / Unsafe.SizeOf<Bgr24>()];
+            ReadOnlySpan<Bgr24> rgbTable = MemoryMarshal.Cast<byte, Bgr24>(palette);
+            Color.FromPixel(rgbTable, colorTable);
+            this.bmpMetadata.ColorTable = colorTable;
+        }
+
         int skipAmount = 0;
         if (this.fileHeader.HasValue)
         {
diff --git a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
index f84e4f9c2..151da1828 100644
--- a/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
@@ -109,6 +109,8 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
     {
         this.memoryAllocator = memoryAllocator;
         this.bitsPerPixel = encoder.BitsPerPixel;
+
+        // TODO: Use a palette quantizer if supplied.
         this.quantizer = encoder.Quantizer ?? KnownQuantizers.Octree;
         this.pixelSamplingStrategy = encoder.PixelSamplingStrategy;
         this.infoHeaderType = encoder.SupportTransparency ? BmpInfoHeaderType.WinVersion4 : BmpInfoHeaderType.WinVersion3;
diff --git a/src/ImageSharp/Formats/Bmp/BmpMetadata.cs b/src/ImageSharp/Formats/Bmp/BmpMetadata.cs
index a2ed1d21d..a50023b27 100644
--- a/src/ImageSharp/Formats/Bmp/BmpMetadata.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpMetadata.cs
@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
 namespace SixLabors.ImageSharp.Formats.Bmp;
@@ -23,6 +23,11 @@ public class BmpMetadata : IDeepCloneable
     {
         this.BitsPerPixel = other.BitsPerPixel;
         this.InfoHeaderType = other.InfoHeaderType;
+
+        if (other.ColorTable?.Length > 0)
+        {
+            this.ColorTable = other.ColorTable.Value.ToArray();
+        }
     }
 
     /// <summary>
@@ -35,8 +40,11 @@ public class BmpMetadata : IDeepCloneable
     /// </summary>
     public BmpBitsPerPixel BitsPerPixel { get; set; } = BmpBitsPerPixel.Pixel24;
 
+    /// <summary>
+    /// Gets or sets the color table, if any.
+    /// </summary>
+    public ReadOnlyMemory<Color>? ColorTable { get; set; }
+
     /// <inheritdoc/>
     public IDeepCloneable DeepClone() => new BmpMetadata(this);
-
-    // TODO: Colors used once we support encoding palette bmps.
 }
diff --git a/src/ImageSharp/Formats/Cur/CurConstants.cs b/src/ImageSharp/Formats/Cur/CurConstants.cs
index 6efd2817c..7abf4c812 100644
--- a/src/ImageSharp/Formats/Cur/CurConstants.cs
+++ b/src/ImageSharp/Formats/Cur/CurConstants.cs
@@ -9,20 +9,31 @@ namespace SixLabors.ImageSharp.Formats.Cur;
 internal static class CurConstants
 {
     /// <summary>
-    /// The list of mimetypes that equate to a ico.
+    /// The list of mime types that equate to a cur.
     /// </summary>
     /// <remarks>
     /// See <see href="https://en.wikipedia.org/wiki/ICO_(file_format)#MIME_type"/>
     /// </remarks>
-    public static readonly IEnumerable<string> MimeTypes = new[]
-    {
-        "application/octet-stream",
-    };
+    public static readonly IEnumerable<string> MimeTypes =
+    [
+
+        // IANA-registered
+        "image/vnd.microsoft.icon",
+
+        // ICO & CUR types used by Windows
+        "image/x-icon",
+
+        // Erroneous types but have been used
+        "image/ico",
+        "image/icon",
+        "text/ico",
+        "application/ico",
+    ];
 
     /// <summary>
-    /// The list of file extensions that equate to a ico.
+    /// The list of file extensions that equate to a cur.
     /// </summary>
-    public static readonly IEnumerable<string> FileExtensions = new[] { "cur" };
+    public static readonly IEnumerable<string> FileExtensions = ["cur"];
 
     public const uint FileHeader = 0x00_02_00_00;
 }
diff --git a/src/ImageSharp/Formats/Cur/CurDecoderCore.cs b/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
index 538f9a2c6..18ab8c75a 100644
--- a/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
+++ b/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
@@ -1,18 +1,24 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Icon;
 using SixLabors.ImageSharp.Metadata;
 
 namespace SixLabors.ImageSharp.Formats.Cur;
 
-internal sealed class CurDecoderCore(DecoderOptions options) : IconDecoderCore(options)
+internal sealed class CurDecoderCore : IconDecoderCore
 {
-    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, Bmp.BmpBitsPerPixel bitsPerPixel)
+    public CurDecoderCore(DecoderOptions options)
+        : base(options)
+    {
+    }
+
+    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, BmpBitsPerPixel bitsPerPixel)
     {
         CurFrameMetadata curFrameMetadata = metadata.GetCurMetadata();
         curFrameMetadata.FromIconDirEntry(entry);
         curFrameMetadata.Compression = compression;
-        curFrameMetadata.BitsPerPixel = bitsPerPixel;
+        curFrameMetadata.BmpBitsPerPixel = bitsPerPixel;
     }
 }
diff --git a/src/ImageSharp/Formats/Cur/CurEncoderCore.cs b/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
index 3a7288b71..a6922d431 100644
--- a/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
+++ b/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
@@ -5,6 +5,10 @@ using SixLabors.ImageSharp.Formats.Icon;
 
 namespace SixLabors.ImageSharp.Formats.Cur;
 
-internal sealed class CurEncoderCore() : IconEncoderCore(IconFileType.CUR)
+internal sealed class CurEncoderCore : IconEncoderCore
 {
+    public CurEncoderCore()
+        : base(IconFileType.CUR)
+    {
+    }
 }
diff --git a/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs b/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs
index e8f3cfe8e..fc5cc5b2c 100644
--- a/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Icon;
 
 namespace SixLabors.ImageSharp.Formats.Cur;
@@ -17,70 +18,48 @@ public class CurFrameMetadata : IDeepCloneable<CurFrameMetadata>, IDeepCloneable
     {
     }
 
-    /// <summary>
-    /// Initializes a new instance of the <see cref="CurFrameMetadata"/> class.
-    /// </summary>
-    /// <param name="width">width</param>
-    /// <param name="height">height</param>
-    /// <param name="colorCount">colorCount</param>
-    /// <param name="hotspotX">hotspotX</param>
-    /// <param name="hotspotY">hotspotY</param>
-    public CurFrameMetadata(byte width, byte height, byte colorCount, ushort hotspotX, ushort hotspotY)
-    {
-        this.EncodingWidth = width;
-        this.EncodingHeight = height;
-        this.ColorCount = colorCount;
-        this.HotspotX = hotspotX;
-        this.HotspotY = hotspotY;
-    }
-
-    /// <inheritdoc cref="CurFrameMetadata()"/>
-    public CurFrameMetadata(CurFrameMetadata metadata)
+    private CurFrameMetadata(CurFrameMetadata metadata)
     {
-        this.EncodingWidth = metadata.EncodingWidth;
-        this.EncodingHeight = metadata.EncodingHeight;
-        this.ColorCount = metadata.ColorCount;
+        this.Compression = metadata.Compression;
         this.HotspotX = metadata.HotspotX;
         this.HotspotY = metadata.HotspotY;
-        this.Compression = metadata.Compression;
+        this.EncodingWidth = metadata.EncodingWidth;
+        this.EncodingHeight = metadata.EncodingHeight;
+        this.BmpBitsPerPixel = metadata.BmpBitsPerPixel;
     }
 
     /// <summary>
-    /// Gets or sets icoFrameCompression.
+    /// Gets or sets the frame compressions format.
     /// </summary>
     public IconFrameCompression Compression { get; set; }
 
     /// <summary>
-    /// Gets or sets ColorCount field. <br />
-    /// Specifies number of colors in the color palette. Should be 0 if the image does not use a color palette.
+    /// Gets or sets the horizontal coordinates of the hotspot in number of pixels from the left.
     /// </summary>
-    // TODO: BmpMetadata does not supported palette yet.
-    public byte ColorCount { get; set; }
+    public ushort HotspotX { get; set; }
 
     /// <summary>
-    /// Gets or sets Specifies the horizontal coordinates of the hotspot in number of pixels from the left.
+    /// Gets or sets the vertical coordinates of the hotspot in number of pixels from the top.
     /// </summary>
-    public ushort HotspotX { get; set; }
+    public ushort HotspotY { get; set; }
 
     /// <summary>
-    /// Gets or sets Specifies the vertical coordinates of the hotspot in number of pixels from the top.
+    /// Gets or sets the encoding width. <br />
+    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels.
     /// </summary>
-    public ushort HotspotY { get; set; }
+    public byte EncodingWidth { get; set; }
 
     /// <summary>
-    /// Gets or sets Height field. <br />
-    /// Specifies image height in pixels. Can be any number between 0 and 255. Value 0 means image height is 256 pixels.
+    /// Gets or sets the encoding height. <br />
+    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels.
     /// </summary>
     public byte EncodingHeight { get; set; }
 
     /// <summary>
-    /// Gets or sets Width field. <br />
-    /// Specifies image width in pixels. Can be any number between 0 and 255. Value 0 means image width is 256 pixels.
+    /// Gets or sets the number of bits per pixel.<br/>
+    /// Used when <see cref="Compression"/> is <see cref="IconFrameCompression.Bmp"/>
     /// </summary>
-    public byte EncodingWidth { get; set; }
-
-    /// <inheritdoc cref="Bmp.BmpMetadata.BitsPerPixel" />
-    public Bmp.BmpBitsPerPixel BitsPerPixel { get; set; } = Bmp.BmpBitsPerPixel.Pixel24;
+    public BmpBitsPerPixel BmpBitsPerPixel { get; set; } = BmpBitsPerPixel.Pixel32;
 
     /// <inheritdoc/>
     public CurFrameMetadata DeepClone() => new(this);
@@ -88,21 +67,27 @@ public class CurFrameMetadata : IDeepCloneable<CurFrameMetadata>, IDeepCloneable
     /// <inheritdoc/>
     IDeepCloneable IDeepCloneable.DeepClone() => this.DeepClone();
 
-    internal void FromIconDirEntry(in IconDirEntry entry)
+    internal void FromIconDirEntry(IconDirEntry entry)
     {
         this.EncodingWidth = entry.Width;
         this.EncodingHeight = entry.Height;
-        this.ColorCount = entry.ColorCount;
         this.HotspotX = entry.Planes;
         this.HotspotY = entry.BitCount;
     }
 
-    internal IconDirEntry ToIconDirEntry() => new()
+    internal IconDirEntry ToIconDirEntry()
     {
-        Width = this.EncodingWidth,
-        Height = this.EncodingHeight,
-        ColorCount = this.ColorCount,
-        Planes = this.HotspotX,
-        BitCount = this.HotspotY,
-    };
+        byte colorCount = this.Compression == IconFrameCompression.Png || this.BmpBitsPerPixel > BmpBitsPerPixel.Pixel8
+            ? (byte)0
+            : (byte)ColorNumerics.GetColorCountForBitDepth((int)this.BmpBitsPerPixel);
+
+        return new()
+        {
+            Width = this.EncodingWidth,
+            Height = this.EncodingHeight,
+            Planes = this.HotspotX,
+            BitCount = this.HotspotY,
+            ColorCount = colorCount
+        };
+    }
 }
diff --git a/src/ImageSharp/Formats/Ico/IcoConstants.cs b/src/ImageSharp/Formats/Ico/IcoConstants.cs
index 0b963a431..116579368 100644
--- a/src/ImageSharp/Formats/Ico/IcoConstants.cs
+++ b/src/ImageSharp/Formats/Ico/IcoConstants.cs
@@ -9,13 +9,14 @@ namespace SixLabors.ImageSharp.Formats.Ico;
 internal static class IcoConstants
 {
     /// <summary>
-    /// The list of mimetypes that equate to a ico.
+    /// The list of mime types that equate to a ico.
     /// </summary>
     /// <remarks>
     /// See <see href="https://en.wikipedia.org/wiki/ICO_(file_format)#MIME_type"/>
     /// </remarks>
-    public static readonly IEnumerable<string> MimeTypes = new[]
-    {
+    public static readonly IEnumerable<string> MimeTypes =
+    [
+
         // IANA-registered
         "image/vnd.microsoft.icon",
 
@@ -27,12 +28,12 @@ internal static class IcoConstants
         "image/icon",
         "text/ico",
         "application/ico",
-    };
+    ];
 
     /// <summary>
     /// The list of file extensions that equate to a ico.
     /// </summary>
-    public static readonly IEnumerable<string> FileExtensions = new[] { "ico" };
+    public static readonly IEnumerable<string> FileExtensions = ["ico"];
 
     public const uint FileHeader = 0x00_01_00_00;
 }
diff --git a/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs b/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
index 78cb0d961..e8629e35b 100644
--- a/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
+++ b/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
@@ -1,18 +1,24 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Icon;
 using SixLabors.ImageSharp.Metadata;
 
 namespace SixLabors.ImageSharp.Formats.Ico;
 
-internal sealed class IcoDecoderCore(DecoderOptions options) : IconDecoderCore(options)
+internal sealed class IcoDecoderCore : IconDecoderCore
 {
-    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, Bmp.BmpBitsPerPixel bitsPerPixel)
+    public IcoDecoderCore(DecoderOptions options)
+        : base(options)
+    {
+    }
+
+    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, BmpBitsPerPixel bitsPerPixel)
     {
         IcoFrameMetadata icoFrameMetadata = metadata.GetIcoMetadata();
         icoFrameMetadata.FromIconDirEntry(entry);
         icoFrameMetadata.Compression = compression;
-        icoFrameMetadata.BitsPerPixel = bitsPerPixel;
+        icoFrameMetadata.BmpBitsPerPixel = bitsPerPixel;
     }
 }
diff --git a/src/ImageSharp/Formats/Ico/IcoEncoder.cs b/src/ImageSharp/Formats/Ico/IcoEncoder.cs
index 0668a7e23..298f93dec 100644
--- a/src/ImageSharp/Formats/Ico/IcoEncoder.cs
+++ b/src/ImageSharp/Formats/Ico/IcoEncoder.cs
@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
 namespace SixLabors.ImageSharp.Formats.Ico;
@@ -6,7 +6,7 @@ namespace SixLabors.ImageSharp.Formats.Ico;
 /// <summary>
 /// Image encoder for writing an image to a stream as a Windows Icon.
 /// </summary>
-public sealed class IcoEncoder : QuantizingImageEncoder
+public sealed class IcoEncoder : ImageEncoder
 {
     /// <inheritdoc/>
     protected override void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
diff --git a/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs b/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
index 12ced58fd..ab3edfbd3 100644
--- a/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
+++ b/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
@@ -5,6 +5,10 @@ using SixLabors.ImageSharp.Formats.Icon;
 
 namespace SixLabors.ImageSharp.Formats.Ico;
 
-internal sealed class IcoEncoderCore() : IconEncoderCore(IconFileType.ICO)
+internal sealed class IcoEncoderCore : IconEncoderCore
 {
+    public IcoEncoderCore()
+        : base(IconFileType.ICO)
+    {
+    }
 }
diff --git a/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs b/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
index 8d7eb17b5..82e4ce3b2 100644
--- a/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
@@ -1,12 +1,13 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Icon;
 
 namespace SixLabors.ImageSharp.Formats.Ico;
 
 /// <summary>
-/// IcoFrameMetadata. TODO: Remove base class and merge into this class.
+/// Provides Ico specific metadata information for the image frame.
 /// </summary>
 public class IcoFrameMetadata : IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
 {
@@ -17,54 +18,36 @@ public class IcoFrameMetadata : IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
     {
     }
 
-    /// <summary>
-    /// Initializes a new instance of the <see cref="IcoFrameMetadata"/> class.
-    /// </summary>
-    /// <param name="width">width</param>
-    /// <param name="height">height</param>
-    /// <param name="colorCount">colorCount</param>
-    public IcoFrameMetadata(byte width, byte height, byte colorCount)
-    {
-        this.EncodingWidth = width;
-        this.EncodingHeight = height;
-        this.ColorCount = colorCount;
-    }
-
-    /// <inheritdoc cref="IcoFrameMetadata()"/>
-    public IcoFrameMetadata(IcoFrameMetadata metadata)
+    private IcoFrameMetadata(IcoFrameMetadata metadata)
     {
+        this.Compression = metadata.Compression;
         this.EncodingWidth = metadata.EncodingWidth;
         this.EncodingHeight = metadata.EncodingHeight;
-        this.ColorCount = metadata.ColorCount;
-        this.Compression = metadata.Compression;
+        this.BmpBitsPerPixel = metadata.BmpBitsPerPixel;
     }
 
     /// <summary>
-    /// Gets or sets icoFrameCompression.
+    /// Gets or sets the frame compressions format.
     /// </summary>
     public IconFrameCompression Compression { get; set; }
 
     /// <summary>
-    /// Gets or sets ColorCount field. <br />
-    /// Specifies number of colors in the color palette. Should be 0 if the image does not use a color palette.
+    /// Gets or sets the encoding width. <br />
+    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels.
     /// </summary>
-    // TODO: BmpMetadata does not supported palette yet.
-    public byte ColorCount { get; set; }
+    public byte EncodingWidth { get; set; }
 
     /// <summary>
-    /// Gets or sets Height field. <br />
-    /// Specifies image height in pixels. Can be any number between 0 and 255. Value 0 means image height is 256 pixels.
+    /// Gets or sets the encoding height. <br />
+    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels.
     /// </summary>
     public byte EncodingHeight { get; set; }
 
     /// <summary>
-    /// Gets or sets Width field. <br />
-    /// Specifies image width in pixels. Can be any number between 0 and 255. Value 0 means image width is 256 pixels.
+    /// Gets or sets the number of bits per pixel.<br/>
+    /// Used when <see cref="Compression"/> is <see cref="IconFrameCompression.Bmp"/>
     /// </summary>
-    public byte EncodingWidth { get; set; }
-
-    /// <inheritdoc cref="Bmp.BmpMetadata.BitsPerPixel" />
-    public Bmp.BmpBitsPerPixel BitsPerPixel { get; set; } = Bmp.BmpBitsPerPixel.Pixel24;
+    public BmpBitsPerPixel BmpBitsPerPixel { get; set; } = BmpBitsPerPixel.Pixel32;
 
     /// <inheritdoc/>
     public IcoFrameMetadata DeepClone() => new(this);
@@ -72,24 +55,29 @@ public class IcoFrameMetadata : IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
     /// <inheritdoc/>
     IDeepCloneable IDeepCloneable.DeepClone() => this.DeepClone();
 
-    internal void FromIconDirEntry(in IconDirEntry entry)
+    internal void FromIconDirEntry(IconDirEntry entry)
     {
         this.EncodingWidth = entry.Width;
         this.EncodingHeight = entry.Height;
-        this.ColorCount = entry.ColorCount;
     }
 
-    internal IconDirEntry ToIconDirEntry() => new()
+    internal IconDirEntry ToIconDirEntry()
     {
-        Width = this.EncodingWidth,
-        Height = this.EncodingHeight,
-        ColorCount = this.ColorCount,
-        Planes = 1,
-        BitCount = this.Compression switch
+        byte colorCount = this.Compression == IconFrameCompression.Png || this.BmpBitsPerPixel > BmpBitsPerPixel.Pixel8
+            ? (byte)0
+            : (byte)ColorNumerics.GetColorCountForBitDepth((int)this.BmpBitsPerPixel);
+
+        return new()
         {
-            IconFrameCompression.Bmp => (ushort)this.BitsPerPixel,
-            IconFrameCompression.Png => 32,
-            _ => throw new NotSupportedException($"Value: {this.Compression}"),
-        },
-    };
+            Width = this.EncodingWidth,
+            Height = this.EncodingHeight,
+            Planes = 1,
+            ColorCount = colorCount,
+            BitCount = this.Compression switch
+            {
+                IconFrameCompression.Bmp => (ushort)this.BmpBitsPerPixel,
+                IconFrameCompression.Png or _ => 32,
+            },
+        };
+    }
 }
diff --git a/src/ImageSharp/Formats/Icon/IconAssert.cs b/src/ImageSharp/Formats/Icon/IconAssert.cs
index 547b6a6eb..398a3e5f4 100644
--- a/src/ImageSharp/Formats/Icon/IconAssert.cs
+++ b/src/ImageSharp/Formats/Icon/IconAssert.cs
@@ -5,14 +5,6 @@ namespace SixLabors.ImageSharp.Formats.Icon;
 
 internal class IconAssert
 {
-    internal static void CanSeek(Stream stream)
-    {
-        if (!stream.CanSeek)
-        {
-            throw new NotSupportedException("This stream cannot support seek");
-        }
-    }
-
     internal static int EndOfStream(int v, int length)
     {
         if (v != length)
@@ -22,28 +14,4 @@ internal class IconAssert
 
         return v;
     }
-
-    internal static long EndOfStream(long v, long length)
-    {
-        if (v != length)
-        {
-            throw new EndOfStreamException();
-        }
-
-        return v;
-    }
-
-    internal static byte Is1ByteSize(int i)
-    {
-        if (i is 256)
-        {
-            return 0;
-        }
-        else if (i > byte.MaxValue)
-        {
-            throw new FormatException("Image size Too Large.");
-        }
-
-        return (byte)i;
-    }
 }
diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index a502b91c9..97d0aec6d 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -10,12 +10,15 @@ using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Icon;
 
-internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderInternals
+internal abstract class IconDecoderCore : IImageDecoderInternals
 {
     private IconDir fileHeader;
     private IconDirEntry[]? entries;
 
-    public DecoderOptions Options { get; } = options;
+    protected IconDecoderCore(DecoderOptions options)
+        => this.Options = options;
+
+    public DecoderOptions Options { get; }
 
     public Size Dimensions { get; private set; }
 
@@ -61,10 +64,11 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
         }
 
         ImageMetadata metadata = new();
+        BmpMetadata? bmpMetadata = null;
         PngMetadata? pngMetadata = null;
         Image<TPixel> result = new(this.Options.Configuration, metadata, decodedEntries.Select(x =>
         {
-            BmpBitsPerPixel bitsPerPixel = default;
+            BmpBitsPerPixel bitsPerPixel = BmpBitsPerPixel.Pixel32;
             ImageFrame<TPixel> target = new(this.Options.Configuration, this.Dimensions);
             ImageFrame<TPixel> source = x.Image.Frames.RootFrameUnsafe;
             for (int y = 0; y < source.Height; y++)
@@ -80,12 +84,12 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
                     pngMetadata = x.Image.Metadata.GetPngMetadata();
                 }
 
-                // Bmp does not contain frame specific metadata.
                 target.Metadata.SetFormatMetadata(PngFormat.Instance, target.Metadata.GetPngMetadata());
             }
             else
             {
-                bitsPerPixel = x.Image.Metadata.GetBmpMetadata().BitsPerPixel;
+                bmpMetadata = x.Image.Metadata.GetBmpMetadata();
+                bitsPerPixel = bmpMetadata.BitsPerPixel;
             }
 
             this.SetFrameMetadata(target.Metadata, this.entries[x.Index], x.Compression, bitsPerPixel);
@@ -96,6 +100,11 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
         }).ToArray());
 
         // Copy the format specific metadata to the image.
+        if (bmpMetadata != null)
+        {
+            result.Metadata.SetFormatMetadata(BmpFormat.Instance, bmpMetadata);
+        }
+
         if (pngMetadata != null)
         {
             result.Metadata.SetFormatMetadata(PngFormat.Instance, pngMetadata);
@@ -114,9 +123,10 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
 
         ImageMetadata metadata = new();
         ImageFrameMetadata[] frames = new ImageFrameMetadata[this.fileHeader.Count];
+        int bpp = 0;
         for (int i = 0; i < frames.Length; i++)
         {
-            BmpBitsPerPixel bitsPerPixel = default;
+            BmpBitsPerPixel bitsPerPixel = BmpBitsPerPixel.Pixel32;
             ref IconDirEntry entry = ref this.entries[i];
 
             // If we hit the end of the stream we should break.
@@ -140,11 +150,13 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
             ImageInfo temp = this.GetDecoder(isPng).Identify(stream, cancellationToken);
 
             frames[i] = new();
-            if (isPng)
+            if (!isPng)
             {
                 bitsPerPixel = temp.Metadata.GetBmpMetadata().BitsPerPixel;
             }
 
+            bpp = Math.Max(bpp, (int)bitsPerPixel);
+
             this.SetFrameMetadata(frames[i], this.entries[i], isPng ? IconFrameCompression.Png : IconFrameCompression.Bmp, bitsPerPixel);
 
             // Since Windows Vista, the size of an image is determined from the BITMAPINFOHEADER structure or PNG image data
@@ -152,7 +164,7 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
             this.Dimensions = new(Math.Max(this.Dimensions.Width, temp.Size.Width), Math.Max(this.Dimensions.Height, temp.Size.Height));
         }
 
-        return new(new(32), this.Dimensions, metadata, frames);
+        return new(new(bpp), this.Dimensions, metadata, frames);
     }
 
     protected abstract void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, BmpBitsPerPixel bitsPerPixel);
@@ -211,15 +223,13 @@ internal abstract class IconDecoderCore(DecoderOptions options) : IImageDecoderI
                 GeneralOptions = this.Options,
             });
         }
-        else
+
+        return new BmpDecoderCore(new()
         {
-            return new BmpDecoderCore(new()
-            {
-                GeneralOptions = this.Options,
-                ProcessedAlphaMask = true,
-                SkipFileHeader = true,
-                UseDoubleHeight = true,
-            });
-        }
+            GeneralOptions = this.Options,
+            ProcessedAlphaMask = true,
+            SkipFileHeader = true,
+            UseDoubleHeight = true,
+        });
     }
 }
diff --git a/src/ImageSharp/Formats/Icon/IconDir.cs b/src/ImageSharp/Formats/Icon/IconDir.cs
index aa583ee1e..3e02538c8 100644
--- a/src/ImageSharp/Formats/Icon/IconDir.cs
+++ b/src/ImageSharp/Formats/Icon/IconDir.cs
@@ -9,8 +9,20 @@ namespace SixLabors.ImageSharp.Formats.Icon;
 internal struct IconDir(ushort reserved, IconFileType type, ushort count)
 {
     public const int Size = 3 * sizeof(ushort);
+
+    /// <summary>
+    /// Reserved. Must always be 0.
+    /// </summary>
     public ushort Reserved = reserved;
+
+    /// <summary>
+    /// Specifies image type: 1 for icon (.ICO) image, 2 for cursor (.CUR) image. Other values are invalid.
+    /// </summary>
     public IconFileType Type = type;
+
+    /// <summary>
+    /// Specifies number of images in the file.
+    /// </summary>
     public ushort Count = count;
 
     public IconDir(IconFileType type)
@@ -23,9 +35,9 @@ internal struct IconDir(ushort reserved, IconFileType type, ushort count)
     {
     }
 
-    public static IconDir Parse(in ReadOnlySpan<byte> data)
+    public static IconDir Parse(ReadOnlySpan<byte> data)
         => MemoryMarshal.Cast<byte, IconDir>(data)[0];
 
-    public unsafe void WriteTo(in Stream stream)
+    public readonly unsafe void WriteTo(Stream stream)
         => stream.Write(MemoryMarshal.Cast<IconDir, byte>([this]));
 }
diff --git a/src/ImageSharp/Formats/Icon/IconDirEntry.cs b/src/ImageSharp/Formats/Icon/IconDirEntry.cs
index 7a8e09e37..eab15dd87 100644
--- a/src/ImageSharp/Formats/Icon/IconDirEntry.cs
+++ b/src/ImageSharp/Formats/Icon/IconDirEntry.cs
@@ -10,25 +10,51 @@ internal struct IconDirEntry
 {
     public const int Size = (4 * sizeof(byte)) + (2 * sizeof(ushort)) + (2 * sizeof(uint));
 
+    /// <summary>
+    /// Specifies image width in pixels. Can be any number between 0 and 255. Value 0 means image width is 256 pixels.
+    /// </summary>
     public byte Width;
 
+    /// <summary>
+    /// Specifies image height in pixels. Can be any number between 0 and 255. Value 0 means image height is 256 pixels.[
+    /// </summary>
     public byte Height;
 
+    /// <summary>
+    /// Specifies number of colors in the color palette. Should be 0 if the image does not use a color palette.
+    /// </summary>
     public byte ColorCount;
 
+    /// <summary>
+    /// Reserved. Should be 0.
+    /// </summary>
     public byte Reserved;
 
+    /// <summary>
+    /// In ICO format: Specifies color planes. Should be 0 or 1.<br/>
+    /// In CUR format: Specifies the horizontal coordinates of the hotspot in number of pixels from the left.
+    /// </summary>
     public ushort Planes;
 
+    /// <summary>
+    /// In ICO format: Specifies bits per pixel.<br/>
+    /// In CUR format: Specifies the vertical coordinates of the hotspot in number of pixels from the top.
+    /// </summary>
     public ushort BitCount;
 
+    /// <summary>
+    /// Specifies the size of the image's data in bytes
+    /// </summary>
     public uint BytesInRes;
 
+    /// <summary>
+    /// Specifies the offset of BMP or PNG data from the beginning of the ICO/CUR file.
+    /// </summary>
     public uint ImageOffset;
 
     public static IconDirEntry Parse(in ReadOnlySpan<byte> data)
         => MemoryMarshal.Cast<byte, IconDirEntry>(data)[0];
 
-    public unsafe void WriteTo(in Stream stream)
+    public readonly unsafe void WriteTo(in Stream stream)
         => stream.Write(MemoryMarshal.Cast<IconDirEntry, byte>([this]));
 }
diff --git a/src/ImageSharp/Formats/Icon/IconEncoderCore.cs b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
index b4d563d4b..5332d9a86 100644
--- a/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
@@ -2,18 +2,23 @@
 // Licensed under the Six Labors Split License.
 
 using System.Diagnostics.CodeAnalysis;
+using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Cur;
 using SixLabors.ImageSharp.Formats.Ico;
+using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing.Processors.Quantization;
 
 namespace SixLabors.ImageSharp.Formats.Icon;
 
-internal abstract class IconEncoderCore(IconFileType iconFileType)
-    : IImageEncoderInternals
+internal abstract class IconEncoderCore : IImageEncoderInternals
 {
+    private readonly IconFileType iconFileType;
     private IconDir fileHeader;
+    private EncodingFrameMetadata[]? entries;
 
-    private IconFrameMetadata[]? entries;
+    protected IconEncoderCore(IconFileType iconFileType)
+        => this.iconFileType = iconFileType;
 
     public void Encode<TPixel>(
         Image<TPixel> image,
@@ -24,17 +29,18 @@ internal abstract class IconEncoderCore(IconFileType iconFileType)
         Guard.NotNull(image, nameof(image));
         Guard.NotNull(stream, nameof(stream));
 
-        IconAssert.CanSeek(stream);
-
         // Stream may not at 0.
         long basePosition = stream.Position;
         this.InitHeader(image);
 
+        // We don't write the header and entries yet as we need to write the image data first.
         int dataOffset = IconDir.Size + (IconDirEntry.Size * this.entries.Length);
         _ = stream.Seek(dataOffset, SeekOrigin.Current);
 
         for (int i = 0; i < image.Frames.Count; i++)
         {
+            // Since Windows Vista, the size of an image is determined from the BITMAPINFOHEADER structure or PNG image data
+            // which technically allows storing icons with larger than 256 pixels, but such larger sizes are not recommended by Microsoft.
             ImageFrame<TPixel> frame = image.Frames[i];
             int width = this.entries[i].Entry.Width;
             if (width is 0)
@@ -50,36 +56,54 @@ internal abstract class IconEncoderCore(IconFileType iconFileType)
 
             this.entries[i].Entry.ImageOffset = (uint)stream.Position;
 
-            Image<TPixel> img = new(width, height);
+            // We crop the frame to the size specified in the metadata.
+            // TODO: we can optimize this by cropping the frame only if the new size is both required and different.
+            using Image<TPixel> encodingFrame = new(width, height);
             for (int y = 0; y < height; y++)
             {
-                frame.PixelBuffer.DangerousGetRowSpan(y)[..width].CopyTo(img.GetRootFramePixelBuffer().DangerousGetRowSpan(y));
+                frame.PixelBuffer.DangerousGetRowSpan(y)[..width]
+                     .CopyTo(encodingFrame.GetRootFramePixelBuffer().DangerousGetRowSpan(y));
             }
 
-            QuantizingImageEncoder encoder = this.entries[i].Compression switch
+            ref EncodingFrameMetadata encodingMetadata = ref this.entries[i];
+
+            QuantizingImageEncoder encoder = encodingMetadata.Compression switch
             {
-                IconFrameCompression.Bmp => new Bmp.BmpEncoder()
+                IconFrameCompression.Bmp => new BmpEncoder()
                 {
+                    // We don't have access to the palette in the metadata so we need to quantize the image
+                    // using a new one generated from the pixel data.
+                    Quantizer = encodingMetadata.Entry.BitCount <= 8
+                    ? new WuQuantizer(new()
+                    {
+                        MaxColors = encodingMetadata.Entry.ColorCount
+                    })
+                    : null,
                     ProcessedAlphaMask = true,
                     UseDoubleHeight = true,
                     SkipFileHeader = true,
                     SupportTransparency = false,
-                    BitsPerPixel = iconFileType is IconFileType.ICO
-                        ? (Bmp.BmpBitsPerPixel?)this.entries[i].Entry.BitCount
-                        : Bmp.BmpBitsPerPixel.Pixel24 // TODO: Here you need to switch to selecting the corresponding value according to the size of the image
+                    BitsPerPixel = encodingMetadata.BmpBitsPerPixel
+                },
+                IconFrameCompression.Png => new PngEncoder()
+                {
+                    // Only 32bit Png supported.
+                    // https://devblogs.microsoft.com/oldnewthing/20101022-00/?p=12473
+                    BitDepth = PngBitDepth.Bit8,
+                    ColorType = PngColorType.RgbWithAlpha
                 },
-                IconFrameCompression.Png => new Png.PngEncoder(),
                 _ => throw new NotSupportedException(),
             };
 
-            encoder.Encode(img, stream);
-            this.entries[i].Entry.BytesInRes = (uint)stream.Position - this.entries[i].Entry.ImageOffset;
+            encoder.Encode(encodingFrame, stream);
+            encodingMetadata.Entry.BytesInRes = (uint)stream.Position - encodingMetadata.Entry.ImageOffset;
         }
 
+        // We now need to rewind the stream and write the header and the entries.
         long endPosition = stream.Position;
         _ = stream.Seek(basePosition, SeekOrigin.Begin);
         this.fileHeader.WriteTo(stream);
-        foreach (IconFrameMetadata frame in this.entries)
+        foreach (EncodingFrameMetadata frame in this.entries)
         {
             frame.Entry.WriteTo(stream);
         }
@@ -88,33 +112,38 @@ internal abstract class IconEncoderCore(IconFileType iconFileType)
     }
 
     [MemberNotNull(nameof(entries))]
-    private void InitHeader(in Image image)
+    private void InitHeader(Image image)
     {
-        this.fileHeader = new(iconFileType, (ushort)image.Frames.Count);
-        this.entries = iconFileType switch
+        this.fileHeader = new(this.iconFileType, (ushort)image.Frames.Count);
+        this.entries = this.iconFileType switch
         {
             IconFileType.ICO =>
             image.Frames.Select(i =>
             {
                 IcoFrameMetadata metadata = i.Metadata.GetIcoMetadata();
-                return new IconFrameMetadata(metadata.Compression, metadata.ToIconDirEntry());
+                return new EncodingFrameMetadata(metadata.Compression, metadata.BmpBitsPerPixel, metadata.ToIconDirEntry());
             }).ToArray(),
             IconFileType.CUR =>
             image.Frames.Select(i =>
             {
                 CurFrameMetadata metadata = i.Metadata.GetCurMetadata();
-                return new IconFrameMetadata(metadata.Compression, metadata.ToIconDirEntry());
+                return new EncodingFrameMetadata(metadata.Compression, metadata.BmpBitsPerPixel, metadata.ToIconDirEntry());
             }).ToArray(),
             _ => throw new NotSupportedException(),
         };
     }
 
-    internal sealed class IconFrameMetadata(IconFrameCompression compression, IconDirEntry iconDirEntry)
+    internal sealed class EncodingFrameMetadata(
+        IconFrameCompression compression,
+        BmpBitsPerPixel bmpBitsPerPixel,
+        IconDirEntry iconDirEntry)
     {
         private IconDirEntry iconDirEntry = iconDirEntry;
 
         public IconFrameCompression Compression { get; set; } = compression;
 
+        public BmpBitsPerPixel BmpBitsPerPixel { get; set; } = bmpBitsPerPixel;
+
         public ref IconDirEntry Entry => ref this.iconDirEntry;
     }
 }
diff --git a/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs b/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
index b66b6c79f..9e7d22de2 100644
--- a/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
+++ b/src/ImageSharp/Formats/Icon/IconImageFormatDetector.cs
@@ -60,9 +60,7 @@ public class IconImageFormatDetector : IImageFormatDetector
 
             return true;
         }
-        else
-        {
-            return false;
-        }
+
+        return false;
     }
 }

From 7c0cd0baab036af0d1726976631beb9beef1487d Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Tue, 18 Jun 2024 21:55:51 +1000
Subject: [PATCH 22/28] Merge separate assert file

---
 src/ImageSharp/Formats/Icon/IconAssert.cs      | 17 -----------------
 src/ImageSharp/Formats/Icon/IconDecoderCore.cs | 14 ++++++++++++--
 src/ImageSharp/Formats/Icon/IconEncoderCore.cs |  3 ++-
 3 files changed, 14 insertions(+), 20 deletions(-)
 delete mode 100644 src/ImageSharp/Formats/Icon/IconAssert.cs

diff --git a/src/ImageSharp/Formats/Icon/IconAssert.cs b/src/ImageSharp/Formats/Icon/IconAssert.cs
deleted file mode 100644
index 398a3e5f4..000000000
--- a/src/ImageSharp/Formats/Icon/IconAssert.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright (c) Six Labors.
-// Licensed under the Six Labors Split License.
-
-namespace SixLabors.ImageSharp.Formats.Icon;
-
-internal class IconAssert
-{
-    internal static int EndOfStream(int v, int length)
-    {
-        if (v != length)
-        {
-            throw new EndOfStreamException();
-        }
-
-        return v;
-    }
-}
diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index 97d0aec6d..a0849fa61 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -175,14 +175,14 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         Span<byte> buffer = stackalloc byte[IconDirEntry.Size];
 
         // ICONDIR
-        _ = IconAssert.EndOfStream(stream.Read(buffer[..IconDir.Size]), IconDir.Size);
+        _ = CheckEndOfStream(stream.Read(buffer[..IconDir.Size]), IconDir.Size);
         this.fileHeader = IconDir.Parse(buffer);
 
         // ICONDIRENTRY
         this.entries = new IconDirEntry[this.fileHeader.Count];
         for (int i = 0; i < this.entries.Length; i++)
         {
-            _ = IconAssert.EndOfStream(stream.Read(buffer[..IconDirEntry.Size]), IconDirEntry.Size);
+            _ = CheckEndOfStream(stream.Read(buffer[..IconDirEntry.Size]), IconDirEntry.Size);
             this.entries[i] = IconDirEntry.Parse(buffer);
         }
 
@@ -232,4 +232,14 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
             UseDoubleHeight = true,
         });
     }
+
+    private static int CheckEndOfStream(int v, int length)
+    {
+        if (v != length)
+        {
+            throw new InvalidImageContentException("Not enough bytes to read icon header.");
+        }
+
+        return v;
+    }
 }
diff --git a/src/ImageSharp/Formats/Icon/IconEncoderCore.cs b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
index 5332d9a86..eb07ab483 100644
--- a/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
@@ -90,7 +90,8 @@ internal abstract class IconEncoderCore : IImageEncoderInternals
                     // Only 32bit Png supported.
                     // https://devblogs.microsoft.com/oldnewthing/20101022-00/?p=12473
                     BitDepth = PngBitDepth.Bit8,
-                    ColorType = PngColorType.RgbWithAlpha
+                    ColorType = PngColorType.RgbWithAlpha,
+                    CompressionLevel = PngCompressionLevel.BestCompression
                 },
                 _ => throw new NotSupportedException(),
             };

From b222a6733e2a978a950b783a7a96979271001841 Mon Sep 17 00:00:00 2001
From: Poker <poker_sang@outlook.com>
Date: Tue, 18 Jun 2024 21:07:08 +0800
Subject: [PATCH 23/28] Add test files

---
 .../Formats/Icon/Cur/CurEncoderTests.cs       |   9 ++
 .../Formats/Icon/Ico/IcoDecoderTests.cs       | 119 ++++++++++++++++++
 tests/ImageSharp.Tests/TestImages.cs          | 114 +++++++++++++++++
 tests/Images/Input/Icon/1bpp_size_15x15.ico   |   3 +
 tests/Images/Input/Icon/1bpp_size_16x16.ico   |   3 +
 tests/Images/Input/Icon/1bpp_size_17x17.ico   |   3 +
 tests/Images/Input/Icon/1bpp_size_1x1.ico     |   3 +
 tests/Images/Input/Icon/1bpp_size_256x256.ico |   3 +
 tests/Images/Input/Icon/1bpp_size_2x2.ico     |   3 +
 tests/Images/Input/Icon/1bpp_size_31x31.ico   |   3 +
 tests/Images/Input/Icon/1bpp_size_32x32.ico   |   3 +
 tests/Images/Input/Icon/1bpp_size_33x33.ico   |   3 +
 tests/Images/Input/Icon/1bpp_size_3x3.ico     |   3 +
 tests/Images/Input/Icon/1bpp_size_4x4.ico     |   3 +
 tests/Images/Input/Icon/1bpp_size_5x5.ico     |   3 +
 tests/Images/Input/Icon/1bpp_size_6x6.ico     |   3 +
 tests/Images/Input/Icon/1bpp_size_7x7.ico     |   3 +
 tests/Images/Input/Icon/1bpp_size_8x8.ico     |   3 +
 tests/Images/Input/Icon/1bpp_size_9x9.ico     |   3 +
 .../Input/Icon/1bpp_transp_not_square.ico     |   3 +
 .../Images/Input/Icon/1bpp_transp_partial.ico |   3 +
 tests/Images/Input/Icon/24bpp_size_15x15.ico  |   3 +
 tests/Images/Input/Icon/24bpp_size_16x16.ico  |   3 +
 tests/Images/Input/Icon/24bpp_size_17x17.ico  |   3 +
 tests/Images/Input/Icon/24bpp_size_1x1.ico    |   3 +
 .../Images/Input/Icon/24bpp_size_256x256.ico  |   3 +
 tests/Images/Input/Icon/24bpp_size_2x2.ico    |   3 +
 tests/Images/Input/Icon/24bpp_size_31x31.ico  |   3 +
 tests/Images/Input/Icon/24bpp_size_32x32.ico  |   3 +
 tests/Images/Input/Icon/24bpp_size_33x33.ico  |   3 +
 tests/Images/Input/Icon/24bpp_size_3x3.ico    |   3 +
 tests/Images/Input/Icon/24bpp_size_4x4.ico    |   3 +
 tests/Images/Input/Icon/24bpp_size_5x5.ico    |   3 +
 tests/Images/Input/Icon/24bpp_size_6x6.ico    |   3 +
 tests/Images/Input/Icon/24bpp_size_7x7.ico    |   3 +
 tests/Images/Input/Icon/24bpp_size_8x8.ico    |   3 +
 tests/Images/Input/Icon/24bpp_size_9x9.ico    |   3 +
 tests/Images/Input/Icon/24bpp_transp.ico      |   3 +
 .../Input/Icon/24bpp_transp_not_square.ico    |   3 +
 .../Input/Icon/24bpp_transp_partial.ico       |   3 +
 tests/Images/Input/Icon/32bpp_size_15x15.ico  |   3 +
 tests/Images/Input/Icon/32bpp_size_16x16.ico  |   3 +
 tests/Images/Input/Icon/32bpp_size_17x17.ico  |   3 +
 tests/Images/Input/Icon/32bpp_size_1x1.ico    |   3 +
 .../Images/Input/Icon/32bpp_size_256x256.ico  |   3 +
 tests/Images/Input/Icon/32bpp_size_2x2.ico    |   3 +
 tests/Images/Input/Icon/32bpp_size_31x31.ico  |   3 +
 tests/Images/Input/Icon/32bpp_size_32x32.ico  |   3 +
 tests/Images/Input/Icon/32bpp_size_33x33.ico  |   3 +
 tests/Images/Input/Icon/32bpp_size_3x3.ico    |   3 +
 tests/Images/Input/Icon/32bpp_size_4x4.ico    |   3 +
 tests/Images/Input/Icon/32bpp_size_5x5.ico    |   3 +
 tests/Images/Input/Icon/32bpp_size_6x6.ico    |   3 +
 tests/Images/Input/Icon/32bpp_size_7x7.ico    |   3 +
 tests/Images/Input/Icon/32bpp_size_8x8.ico    |   3 +
 tests/Images/Input/Icon/32bpp_size_9x9.ico    |   3 +
 tests/Images/Input/Icon/32bpp_transp.ico      |   3 +
 .../Input/Icon/32bpp_transp_not_square.ico    |   3 +
 .../Input/Icon/32bpp_transp_partial.ico       |   3 +
 tests/Images/Input/Icon/4bpp_size_15x15.ico   |   3 +
 tests/Images/Input/Icon/4bpp_size_16x16.ico   |   3 +
 tests/Images/Input/Icon/4bpp_size_17x17.ico   |   3 +
 tests/Images/Input/Icon/4bpp_size_1x1.ico     |   3 +
 tests/Images/Input/Icon/4bpp_size_256x256.ico |   3 +
 tests/Images/Input/Icon/4bpp_size_2x2.ico     |   3 +
 tests/Images/Input/Icon/4bpp_size_31x31.ico   |   3 +
 tests/Images/Input/Icon/4bpp_size_32x32.ico   |   3 +
 tests/Images/Input/Icon/4bpp_size_33x33.ico   |   3 +
 tests/Images/Input/Icon/4bpp_size_3x3.ico     |   3 +
 tests/Images/Input/Icon/4bpp_size_4x4.ico     |   3 +
 tests/Images/Input/Icon/4bpp_size_5x5.ico     |   3 +
 tests/Images/Input/Icon/4bpp_size_6x6.ico     |   3 +
 tests/Images/Input/Icon/4bpp_size_7x7.ico     |   3 +
 tests/Images/Input/Icon/4bpp_size_8x8.ico     |   3 +
 tests/Images/Input/Icon/4bpp_size_9x9.ico     |   3 +
 .../Input/Icon/4bpp_transp_not_square.ico     |   3 +
 .../Images/Input/Icon/4bpp_transp_partial.ico |   3 +
 tests/Images/Input/Icon/8bpp_size_15x15.ico   |   3 +
 tests/Images/Input/Icon/8bpp_size_16x16.ico   |   3 +
 tests/Images/Input/Icon/8bpp_size_17x17.ico   |   3 +
 tests/Images/Input/Icon/8bpp_size_1x1.ico     |   3 +
 tests/Images/Input/Icon/8bpp_size_256x256.ico |   3 +
 tests/Images/Input/Icon/8bpp_size_2x2.ico     |   3 +
 tests/Images/Input/Icon/8bpp_size_31x31.ico   |   3 +
 tests/Images/Input/Icon/8bpp_size_32x32.ico   |   3 +
 tests/Images/Input/Icon/8bpp_size_33x33.ico   |   3 +
 tests/Images/Input/Icon/8bpp_size_3x3.ico     |   3 +
 tests/Images/Input/Icon/8bpp_size_4x4.ico     |   3 +
 tests/Images/Input/Icon/8bpp_size_5x5.ico     |   3 +
 tests/Images/Input/Icon/8bpp_size_6x6.ico     |   3 +
 tests/Images/Input/Icon/8bpp_size_7x7.ico     |   3 +
 tests/Images/Input/Icon/8bpp_size_8x8.ico     |   3 +
 tests/Images/Input/Icon/8bpp_size_9x9.ico     |   3 +
 .../Input/Icon/8bpp_transp_not_square.ico     |   3 +
 .../Images/Input/Icon/8bpp_transp_partial.ico |   3 +
 tests/Images/Input/Icon/cur_fake.ico          |   3 +
 tests/Images/Input/Icon/cur_real.cur          |   3 +
 tests/Images/Input/Icon/ico_fake.cur          |   3 +
 tests/Images/Input/Icon/invalid_RLE4.ico      |   3 +
 tests/Images/Input/Icon/invalid_RLE8.ico      |   3 +
 tests/Images/Input/Icon/invalid_all.ico       |   3 +
 tests/Images/Input/Icon/invalid_bpp.ico       |   3 +
 .../Images/Input/Icon/invalid_compression.ico |   3 +
 tests/Images/Input/Icon/invalid_png.ico       |   3 +
 tests/Images/Input/Icon/mixed_bmp_png_a.ico   |   3 +
 tests/Images/Input/Icon/mixed_bmp_png_b.ico   |   3 +
 tests/Images/Input/Icon/mixed_bmp_png_c.ico   |   3 +
 tests/Images/Input/Icon/multi_size_a.ico      |   3 +
 tests/Images/Input/Icon/multi_size_b.ico      |   3 +
 tests/Images/Input/Icon/multi_size_c.ico      |   3 +
 tests/Images/Input/Icon/multi_size_d.ico      |   3 +
 tests/Images/Input/Icon/multi_size_e.ico      |   3 +
 tests/Images/Input/Icon/multi_size_f.ico      |   3 +
 .../Input/Icon/multi_size_multi_bits_a.ico    |   3 +
 .../Input/Icon/multi_size_multi_bits_b.ico    |   3 +
 .../Input/Icon/multi_size_multi_bits_c.ico    |   3 +
 .../Input/Icon/multi_size_multi_bits_d.ico    |   3 +
 117 files changed, 584 insertions(+)
 create mode 100644 tests/Images/Input/Icon/1bpp_size_15x15.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_16x16.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_17x17.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_1x1.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_256x256.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_2x2.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_31x31.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_32x32.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_33x33.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_3x3.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_4x4.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_5x5.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_6x6.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_7x7.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_8x8.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_size_9x9.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_transp_not_square.ico
 create mode 100644 tests/Images/Input/Icon/1bpp_transp_partial.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_15x15.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_16x16.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_17x17.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_1x1.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_256x256.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_2x2.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_31x31.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_32x32.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_33x33.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_3x3.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_4x4.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_5x5.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_6x6.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_7x7.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_8x8.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_size_9x9.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_transp.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_transp_not_square.ico
 create mode 100644 tests/Images/Input/Icon/24bpp_transp_partial.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_15x15.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_16x16.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_17x17.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_1x1.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_256x256.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_2x2.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_31x31.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_32x32.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_33x33.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_3x3.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_4x4.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_5x5.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_6x6.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_7x7.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_8x8.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_size_9x9.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_transp.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_transp_not_square.ico
 create mode 100644 tests/Images/Input/Icon/32bpp_transp_partial.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_15x15.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_16x16.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_17x17.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_1x1.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_256x256.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_2x2.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_31x31.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_32x32.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_33x33.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_3x3.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_4x4.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_5x5.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_6x6.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_7x7.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_8x8.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_size_9x9.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_transp_not_square.ico
 create mode 100644 tests/Images/Input/Icon/4bpp_transp_partial.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_15x15.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_16x16.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_17x17.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_1x1.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_256x256.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_2x2.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_31x31.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_32x32.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_33x33.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_3x3.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_4x4.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_5x5.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_6x6.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_7x7.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_8x8.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_size_9x9.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_transp_not_square.ico
 create mode 100644 tests/Images/Input/Icon/8bpp_transp_partial.ico
 create mode 100644 tests/Images/Input/Icon/cur_fake.ico
 create mode 100644 tests/Images/Input/Icon/cur_real.cur
 create mode 100644 tests/Images/Input/Icon/ico_fake.cur
 create mode 100644 tests/Images/Input/Icon/invalid_RLE4.ico
 create mode 100644 tests/Images/Input/Icon/invalid_RLE8.ico
 create mode 100644 tests/Images/Input/Icon/invalid_all.ico
 create mode 100644 tests/Images/Input/Icon/invalid_bpp.ico
 create mode 100644 tests/Images/Input/Icon/invalid_compression.ico
 create mode 100644 tests/Images/Input/Icon/invalid_png.ico
 create mode 100644 tests/Images/Input/Icon/mixed_bmp_png_a.ico
 create mode 100644 tests/Images/Input/Icon/mixed_bmp_png_b.ico
 create mode 100644 tests/Images/Input/Icon/mixed_bmp_png_c.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_a.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_b.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_c.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_d.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_e.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_f.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_multi_bits_a.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_multi_bits_b.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_multi_bits_c.ico
 create mode 100644 tests/Images/Input/Icon/multi_size_multi_bits_d.ico

diff --git a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
index 9908786f1..58213397c 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.Diagnostics;
 using SixLabors.ImageSharp.Formats.Cur;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Cur;
@@ -29,4 +30,12 @@ public class CurEncoderTests
         memStream.Seek(0, SeekOrigin.Begin);
         CurDecoder.Instance.Decode(new(), memStream);
     }
+
+    [Theory]
+    [WithFile(CurFake, PixelTypes.Rgba32)]
+    [WithFile(CurReal, PixelTypes.Rgba32)]
+    public void CurDecoder_Decode2(TestImageProvider<Rgba32> provider)
+    {
+        Debug.Assert(false);
+    }
 }
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
index 56378653a..ab4ec0a3d 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.Diagnostics;
 using SixLabors.ImageSharp.Formats.Ico;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Ico;
@@ -21,4 +22,122 @@ public class IcoDecoderTests
 
         // TODO: Assert metadata, frame count, etc
     }
+
+    [Theory]
+    [WithFile(Bpp1_size_15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_size_9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_transp_not_square, PixelTypes.Rgba32)]
+    [WithFile(Bpp1_transp_partial, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_size_9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_transp_not_square, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_transp_partial, PixelTypes.Rgba32)]
+    [WithFile(Bpp24_transp, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_size_9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_transp_not_square, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_transp_partial, PixelTypes.Rgba32)]
+    [WithFile(Bpp32_transp, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_size_9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_transp_not_square, PixelTypes.Rgba32)]
+    [WithFile(Bpp4_transp_partial, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_size_9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_transp_not_square, PixelTypes.Rgba32)]
+    [WithFile(Bpp8_transp_partial, PixelTypes.Rgba32)]
+    [WithFile(IcoFake, PixelTypes.Rgba32)]
+    [WithFile(Invalid_all, PixelTypes.Rgba32)]
+    [WithFile(Invalid_bpp, PixelTypes.Rgba32)]
+    [WithFile(Invalid_compression, PixelTypes.Rgba32)]
+    [WithFile(Invalid_png, PixelTypes.Rgba32)]
+    [WithFile(Invalid_RLE4, PixelTypes.Rgba32)]
+    [WithFile(Invalid_RLE8, PixelTypes.Rgba32)]
+    [WithFile(Mixed_bmp_png_a, PixelTypes.Rgba32)]
+    [WithFile(Mixed_bmp_png_b, PixelTypes.Rgba32)]
+    [WithFile(Mixed_bmp_png_c, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_a, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_b, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_c, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_d, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_e, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_f, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_multi_bits_a, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_multi_bits_b, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_multi_bits_c, PixelTypes.Rgba32)]
+    [WithFile(Multi_size_multi_bits_d, PixelTypes.Rgba32)]
+    public void IcoDecoder_Decode2(TestImageProvider<Rgba32> provider)
+    {
+        Debug.Assert(false);
+    }
 }
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index 8b76abca2..6db11c78f 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -1126,10 +1126,124 @@ public static class TestImages
     public static class Ico
     {
         public const string Flutter = "Icon/flutter.ico";
+        public const string Bpp1_size_15x15 = "Icon/1bpp_size_15x15.ico";
+        public const string Bpp1_size_16x16 = "Icon/1bpp_size_16x16.ico";
+        public const string Bpp1_size_17x17 = "Icon/1bpp_size_17x17.ico";
+        public const string Bpp1_size_1x1 = "Icon/1bpp_size_1x1.ico";
+        public const string Bpp1_size_256x256 = "Icon/1bpp_size_256x256.ico";
+        public const string Bpp1_size_2x2 = "Icon/1bpp_size_2x2.ico";
+        public const string Bpp1_size_31x31 = "Icon/1bpp_size_31x31.ico";
+        public const string Bpp1_size_32x32 = "Icon/1bpp_size_32x32.ico";
+        public const string Bpp1_size_33x33 = "Icon/1bpp_size_33x33.ico";
+        public const string Bpp1_size_3x3 = "Icon/1bpp_size_3x3.ico";
+        public const string Bpp1_size_4x4 = "Icon/1bpp_size_4x4.ico";
+        public const string Bpp1_size_5x5 = "Icon/1bpp_size_5x5.ico";
+        public const string Bpp1_size_6x6 = "Icon/1bpp_size_6x6.ico";
+        public const string Bpp1_size_7x7 = "Icon/1bpp_size_7x7.ico";
+        public const string Bpp1_size_8x8 = "Icon/1bpp_size_8x8.ico";
+        public const string Bpp1_size_9x9 = "Icon/1bpp_size_9x9.ico";
+        public const string Bpp1_transp_not_square = "Icon/1bpp_transp_not_square.ico";
+        public const string Bpp1_transp_partial = "Icon/1bpp_transp_partial.ico";
+        public const string Bpp24_size_15x15 = "Icon/24bpp_size_15x15.ico";
+        public const string Bpp24_size_16x16 = "Icon/24bpp_size_16x16.ico";
+        public const string Bpp24_size_17x17 = "Icon/24bpp_size_17x17.ico";
+        public const string Bpp24_size_1x1 = "Icon/24bpp_size_1x1.ico";
+        public const string Bpp24_size_256x256 = "Icon/24bpp_size_256x256.ico";
+        public const string Bpp24_size_2x2 = "Icon/24bpp_size_2x2.ico";
+        public const string Bpp24_size_31x31 = "Icon/24bpp_size_31x31.ico";
+        public const string Bpp24_size_32x32 = "Icon/24bpp_size_32x32.ico";
+        public const string Bpp24_size_33x33 = "Icon/24bpp_size_33x33.ico";
+        public const string Bpp24_size_3x3 = "Icon/24bpp_size_3x3.ico";
+        public const string Bpp24_size_4x4 = "Icon/24bpp_size_4x4.ico";
+        public const string Bpp24_size_5x5 = "Icon/24bpp_size_5x5.ico";
+        public const string Bpp24_size_6x6 = "Icon/24bpp_size_6x6.ico";
+        public const string Bpp24_size_7x7 = "Icon/24bpp_size_7x7.ico";
+        public const string Bpp24_size_8x8 = "Icon/24bpp_size_8x8.ico";
+        public const string Bpp24_size_9x9 = "Icon/24bpp_size_9x9.ico";
+        public const string Bpp24_transp_not_square = "Icon/24bpp_transp_not_square.ico";
+        public const string Bpp24_transp_partial = "Icon/24bpp_transp_partial.ico";
+        public const string Bpp24_transp = "Icon/24bpp_transp.ico";
+        public const string Bpp32_size_15x15 = "Icon/32bpp_size_15x15.ico";
+        public const string Bpp32_size_16x16 = "Icon/32bpp_size_16x16.ico";
+        public const string Bpp32_size_17x17 = "Icon/32bpp_size_17x17.ico";
+        public const string Bpp32_size_1x1 = "Icon/32bpp_size_1x1.ico";
+        public const string Bpp32_size_256x256 = "Icon/32bpp_size_256x256.ico";
+        public const string Bpp32_size_2x2 = "Icon/32bpp_size_2x2.ico";
+        public const string Bpp32_size_31x31 = "Icon/32bpp_size_31x31.ico";
+        public const string Bpp32_size_32x32 = "Icon/32bpp_size_32x32.ico";
+        public const string Bpp32_size_33x33 = "Icon/32bpp_size_33x33.ico";
+        public const string Bpp32_size_3x3 = "Icon/32bpp_size_3x3.ico";
+        public const string Bpp32_size_4x4 = "Icon/32bpp_size_4x4.ico";
+        public const string Bpp32_size_5x5 = "Icon/32bpp_size_5x5.ico";
+        public const string Bpp32_size_6x6 = "Icon/32bpp_size_6x6.ico";
+        public const string Bpp32_size_7x7 = "Icon/32bpp_size_7x7.ico";
+        public const string Bpp32_size_8x8 = "Icon/32bpp_size_8x8.ico";
+        public const string Bpp32_size_9x9 = "Icon/32bpp_size_9x9.ico";
+        public const string Bpp32_transp_not_square = "Icon/32bpp_transp_not_square.ico";
+        public const string Bpp32_transp_partial = "Icon/32bpp_transp_partial.ico";
+        public const string Bpp32_transp = "Icon/32bpp_transp.ico";
+        public const string Bpp4_size_15x15 = "Icon/4bpp_size_15x15.ico";
+        public const string Bpp4_size_16x16 = "Icon/4bpp_size_16x16.ico";
+        public const string Bpp4_size_17x17 = "Icon/4bpp_size_17x17.ico";
+        public const string Bpp4_size_1x1 = "Icon/4bpp_size_1x1.ico";
+        public const string Bpp4_size_256x256 = "Icon/4bpp_size_256x256.ico";
+        public const string Bpp4_size_2x2 = "Icon/4bpp_size_2x2.ico";
+        public const string Bpp4_size_31x31 = "Icon/4bpp_size_31x31.ico";
+        public const string Bpp4_size_32x32 = "Icon/4bpp_size_32x32.ico";
+        public const string Bpp4_size_33x33 = "Icon/4bpp_size_33x33.ico";
+        public const string Bpp4_size_3x3 = "Icon/4bpp_size_3x3.ico";
+        public const string Bpp4_size_4x4 = "Icon/4bpp_size_4x4.ico";
+        public const string Bpp4_size_5x5 = "Icon/4bpp_size_5x5.ico";
+        public const string Bpp4_size_6x6 = "Icon/4bpp_size_6x6.ico";
+        public const string Bpp4_size_7x7 = "Icon/4bpp_size_7x7.ico";
+        public const string Bpp4_size_8x8 = "Icon/4bpp_size_8x8.ico";
+        public const string Bpp4_size_9x9 = "Icon/4bpp_size_9x9.ico";
+        public const string Bpp4_transp_not_square = "Icon/4bpp_transp_not_square.ico";
+        public const string Bpp4_transp_partial = "Icon/4bpp_transp_partial.ico";
+        public const string Bpp8_size_15x15 = "Icon/8bpp_size_15x15.ico";
+        public const string Bpp8_size_16x16 = "Icon/8bpp_size_16x16.ico";
+        public const string Bpp8_size_17x17 = "Icon/8bpp_size_17x17.ico";
+        public const string Bpp8_size_1x1 = "Icon/8bpp_size_1x1.ico";
+        public const string Bpp8_size_256x256 = "Icon/8bpp_size_256x256.ico";
+        public const string Bpp8_size_2x2 = "Icon/8bpp_size_2x2.ico";
+        public const string Bpp8_size_31x31 = "Icon/8bpp_size_31x31.ico";
+        public const string Bpp8_size_32x32 = "Icon/8bpp_size_32x32.ico";
+        public const string Bpp8_size_33x33 = "Icon/8bpp_size_33x33.ico";
+        public const string Bpp8_size_3x3 = "Icon/8bpp_size_3x3.ico";
+        public const string Bpp8_size_4x4 = "Icon/8bpp_size_4x4.ico";
+        public const string Bpp8_size_5x5 = "Icon/8bpp_size_5x5.ico";
+        public const string Bpp8_size_6x6 = "Icon/8bpp_size_6x6.ico";
+        public const string Bpp8_size_7x7 = "Icon/8bpp_size_7x7.ico";
+        public const string Bpp8_size_8x8 = "Icon/8bpp_size_8x8.ico";
+        public const string Bpp8_size_9x9 = "Icon/8bpp_size_9x9.ico";
+        public const string Bpp8_transp_not_square = "Icon/8bpp_transp_not_square.ico";
+        public const string Bpp8_transp_partial = "Icon/8bpp_transp_partial.ico";
+        public const string Invalid_all = "Icon/invalid_all.ico";
+        public const string IcoFake = "Icon/ico_fake.cur";
+        public const string Invalid_bpp = "Icon/invalid_bpp.ico";
+        public const string Invalid_compression = "Icon/invalid_compression.ico";
+        public const string Invalid_png = "Icon/invalid_png.ico";
+        public const string Invalid_RLE4 = "Icon/invalid_RLE4.ico";
+        public const string Invalid_RLE8 = "Icon/invalid_RLE8.ico";
+        public const string Mixed_bmp_png_a = "Icon/mixed_bmp_png_a.ico";
+        public const string Mixed_bmp_png_b = "Icon/mixed_bmp_png_b.ico";
+        public const string Mixed_bmp_png_c = "Icon/mixed_bmp_png_c.ico";
+        public const string Multi_size_a = "Icon/multi_size_a.ico";
+        public const string Multi_size_b = "Icon/multi_size_b.ico";
+        public const string Multi_size_c = "Icon/multi_size_c.ico";
+        public const string Multi_size_d = "Icon/multi_size_d.ico";
+        public const string Multi_size_e = "Icon/multi_size_e.ico";
+        public const string Multi_size_f = "Icon/multi_size_f.ico";
+        public const string Multi_size_multi_bits_a = "Icon/multi_size_multi_bits_a.ico";
+        public const string Multi_size_multi_bits_b = "Icon/multi_size_multi_bits_b.ico";
+        public const string Multi_size_multi_bits_c = "Icon/multi_size_multi_bits_c.ico";
+        public const string Multi_size_multi_bits_d = "Icon/multi_size_multi_bits_d.ico";
     }
 
     public static class Cur
     {
         public const string WindowsMouse = "Icon/aero_arrow.cur";
+        public const string CurReal = "Icon/cur_real.cur";
+        public const string CurFake = "Icon/cur_fake.ico";
     }
 }
diff --git a/tests/Images/Input/Icon/1bpp_size_15x15.ico b/tests/Images/Input/Icon/1bpp_size_15x15.ico
new file mode 100644
index 000000000..39fc9c521
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_15x15.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:846dda605ee23bb641534b272fa57300eacd85038feea5dd1a3f6d4b543a935e
+size 190
diff --git a/tests/Images/Input/Icon/1bpp_size_16x16.ico b/tests/Images/Input/Icon/1bpp_size_16x16.ico
new file mode 100644
index 000000000..6179678bc
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_16x16.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:029d0438eda83d4d9e087cf79abe2d0234728c37f570de808355c0e79c71be17
+size 198
diff --git a/tests/Images/Input/Icon/1bpp_size_17x17.ico b/tests/Images/Input/Icon/1bpp_size_17x17.ico
new file mode 100644
index 000000000..90138a08d
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_17x17.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:8db024a49fdd91c9d5d1fc0c1d6f60991518a5776031f58cdafbdd3ed9e4f26b
+size 206
diff --git a/tests/Images/Input/Icon/1bpp_size_1x1.ico b/tests/Images/Input/Icon/1bpp_size_1x1.ico
new file mode 100644
index 000000000..1161a3f3c
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_1x1.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:f13d1bbfa5b29bc386270cb492b705eded0825a9eb3a6341f4ea2b3dbe085cd1
+size 78
diff --git a/tests/Images/Input/Icon/1bpp_size_256x256.ico b/tests/Images/Input/Icon/1bpp_size_256x256.ico
new file mode 100644
index 000000000..d6524a31f
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_256x256.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c1aa37daf2fd65b424c5e13e94bed165328e624584cc5664d73bb4030a1e1f12
+size 16454
diff --git a/tests/Images/Input/Icon/1bpp_size_2x2.ico b/tests/Images/Input/Icon/1bpp_size_2x2.ico
new file mode 100644
index 000000000..73394156a
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_2x2.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:18be2a5384812de1bec70733fb0b283a159edc5d0bc03981de8fb3ccddb8911e
+size 86
diff --git a/tests/Images/Input/Icon/1bpp_size_31x31.ico b/tests/Images/Input/Icon/1bpp_size_31x31.ico
new file mode 100644
index 000000000..8dffe659f
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_31x31.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a3a4e7964e3ed5ca2a98929e2f903a6b969961410aab6a935a0c54fbe716d0c3
+size 318
diff --git a/tests/Images/Input/Icon/1bpp_size_32x32.ico b/tests/Images/Input/Icon/1bpp_size_32x32.ico
new file mode 100644
index 000000000..e281eb378
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_32x32.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:06a55f8219234e43beec6776fe15a7d6d4ad314deaf64df115ea45f2100e5283
+size 326
diff --git a/tests/Images/Input/Icon/1bpp_size_33x33.ico b/tests/Images/Input/Icon/1bpp_size_33x33.ico
new file mode 100644
index 000000000..c5e4677d3
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_33x33.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:82fa82f6b954515eace3cdd6d4681abd149b37354a7dee4f0d1966f516f27850
+size 598
diff --git a/tests/Images/Input/Icon/1bpp_size_3x3.ico b/tests/Images/Input/Icon/1bpp_size_3x3.ico
new file mode 100644
index 000000000..89872b959
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_3x3.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:5ff0bf1c415925642d99691a9a9a6b92d9995447bc62ed80b9b0c6d4efdcd19b
+size 94
diff --git a/tests/Images/Input/Icon/1bpp_size_4x4.ico b/tests/Images/Input/Icon/1bpp_size_4x4.ico
new file mode 100644
index 000000000..1e47b4596
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_4x4.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:5853ba73b06e0f2a0c71850011526419db3bd7c76e5b7b2f6b22f748ce919bf2
+size 102
diff --git a/tests/Images/Input/Icon/1bpp_size_5x5.ico b/tests/Images/Input/Icon/1bpp_size_5x5.ico
new file mode 100644
index 000000000..5152c7575
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_5x5.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:ecd253a6862ec9a9870c8a8a370528b28c22d23247dfc29e09fab65d95b9416d
+size 110
diff --git a/tests/Images/Input/Icon/1bpp_size_6x6.ico b/tests/Images/Input/Icon/1bpp_size_6x6.ico
new file mode 100644
index 000000000..a1d5c09c0
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_6x6.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a80c7f8d37dc3997bcd674a5af835cae802cacbf5d65020f0aaae67f70cfc31e
+size 118
diff --git a/tests/Images/Input/Icon/1bpp_size_7x7.ico b/tests/Images/Input/Icon/1bpp_size_7x7.ico
new file mode 100644
index 000000000..9c5a227e3
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_7x7.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:00a26274e8563e6378f8bfa4d1aa9695030593a38791ca366cecd3949b0f52af
+size 126
diff --git a/tests/Images/Input/Icon/1bpp_size_8x8.ico b/tests/Images/Input/Icon/1bpp_size_8x8.ico
new file mode 100644
index 000000000..c019914ee
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_8x8.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:78150aee2f5d5ccd2a172abfe11f1127efb950cb9173e22e380809afb2a94d3c
+size 134
diff --git a/tests/Images/Input/Icon/1bpp_size_9x9.ico b/tests/Images/Input/Icon/1bpp_size_9x9.ico
new file mode 100644
index 000000000..2f3fd28eb
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_size_9x9.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d8cecf833b31208710c1dde1bed3322a95453468a3f4b39afdad66ac9bc5f86b
+size 142
diff --git a/tests/Images/Input/Icon/1bpp_transp_not_square.ico b/tests/Images/Input/Icon/1bpp_transp_not_square.ico
new file mode 100644
index 000000000..1c678ec40
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_transp_not_square.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:bd9f41711b53d4e1e915ddb992522b97a981fbe3f4536826f0c66e2d6a3677fb
+size 182
diff --git a/tests/Images/Input/Icon/1bpp_transp_partial.ico b/tests/Images/Input/Icon/1bpp_transp_partial.ico
new file mode 100644
index 000000000..6365a53df
--- /dev/null
+++ b/tests/Images/Input/Icon/1bpp_transp_partial.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:cedcd221abf4b95115f9f8f34f15da456b09e7e56972cced24a99fa56bf8aca9
+size 326
diff --git a/tests/Images/Input/Icon/24bpp_size_15x15.ico b/tests/Images/Input/Icon/24bpp_size_15x15.ico
new file mode 100644
index 000000000..f8697e2b5
--- /dev/null
+++ b/tests/Images/Input/Icon/24bpp_size_15x15.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b506403852d936d14975ed9aba1c50ab3873cbbd81afcf38381f8e5e841fafd0
+size 842
diff --git a/tests/Images/Input/Icon/24bpp_size_16x16.ico b/tests/Images/Input/Icon/24bpp_size_16x16.ico
new file mode 100644
index 000000000..e6de107d7
--- /dev/null
+++ b/tests/Images/Input/Icon/24bpp_size_16x16.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:8bfa9de0f613e9e82e9037193c4124f87d05ac1390459e2f018da45c16200de6
+size 894
diff --git a/tests/Images/Input/Icon/24bpp_size_17x17.ico b/tests/Images/Input/Icon/24bpp_size_17x17.ico
new file mode 100644
index 000000000..2c37ffa8b
--- /dev/null
+++ b/tests/Images/Input/Icon/24bpp_size_17x17.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a4cd2ad22e55000a706d365e0a3395f3e4d9a3933c00880d5f12903ac0aed60e
+size 1014
diff --git a/tests/Images/Input/Icon/24bpp_size_1x1.ico b/tests/Images/Input/Icon/24bpp_size_1x1.ico
new file mode 100644
index 000000000..f9137f61a
--- /dev/null
+++ b/tests/Images/Input/Icon/24bpp_size_1x1.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:3b20e9a6479c3831b7af75d30bc909ce3046e45384bfd62d7a10ac6816c1c947
+size 70
diff --git a/tests/Images/Input/Icon/24bpp_size_256x256.ico b/tests/Images/Input/Icon/24bpp_size_256x256.ico
new file mode 100644
index 000000000..08f928c8e
--- /dev/null
+++ b/tests/Images/Input/Icon/24bpp_size_256x256.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:1175641f39e68bd6cd38b8f64f02510b22c5a642afc7503d357b064163b3d37b
+size 204862
diff --git a/tests/Images/Input/Icon/24bpp_size_2x2.ico b/tests/Images/Input/Icon/24bpp_size_2x2.ico
new file mode 100644
index 000000000..d6d472a25
--- /dev/null
+++ b/tests/Images/Input/Icon/24bpp_size_2x2.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:72a1380a306b51ae37eabd3edeb0b134b0f8e8e120e6c64b6b08bd833a9c70a4
+size 86
diff --git a/tests/Images/Input/Icon/24bpp_size_31x31.ico b/tests/Images/Input/Icon/24bpp_size_31x31.ico
new file mode 100644
index 000000000..5c585c582
--- /dev/null
+++ b/tests/Images/Input/Icon/24bpp_size_31x31.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:574b0971908b44334f1f3be79e5b0ff336e74a8b9947b43a295d3a2b86733965
+size 3162
diff --git a/tests/Images/Input/Icon/24bpp_size_32x32.ico b/tests/Images/Input/Icon/24bpp_size_32x32.ico
new file mode 100644
index 000000000..3663b8767
--- /dev/null
+++ b/tests/Images/Input/Icon/24bpp_size_32x32.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:fa45880e5611436fc06de0603481d0a61044e52a1a053961fdda1139bb5660a6
+size 3262
diff --git a/tests/Images/Input/Icon/24bpp_size_33x33.ico b/tests/Images/Input/Icon/24bpp_size_33x33.ico
new file mode 100644
index 000000000..4834b48c8
--- /dev/null
+++ b/tests/Images/Input/Icon/24bpp_size_33x33.ico
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:8704a77d6264f6f104e23950099e3d3a4a577787e67c7c39d7925f9d0a347572
+size 3626
diff --git a/tests/Images/Input/Icon/24bpp_size_3x3.ico b/tests/Images/Input/Icon/24bpp_size_3x3.ico
new file mode 100644
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new file mode 100644
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--- /dev/null
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new file mode 100644
index 000000000..6b6bbdc9f
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new file mode 100644
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--- /dev/null
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diff --git a/tests/Images/Input/Icon/cur_fake.ico b/tests/Images/Input/Icon/cur_fake.ico
new file mode 100644
index 000000000..cad7542c8
--- /dev/null
+++ b/tests/Images/Input/Icon/cur_fake.ico
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+version https://git-lfs.github.com/spec/v1
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new file mode 100644
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--- /dev/null
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new file mode 100644
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--- /dev/null
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new file mode 100644
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new file mode 100644
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new file mode 100644
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new file mode 100644
index 000000000..7e697d3d2
--- /dev/null
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diff --git a/tests/Images/Input/Icon/invalid_png.ico b/tests/Images/Input/Icon/invalid_png.ico
new file mode 100644
index 000000000..cbd394fc6
--- /dev/null
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new file mode 100644
index 000000000..f35027255
--- /dev/null
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new file mode 100644
index 000000000..3efdcab74
--- /dev/null
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new file mode 100644
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--- /dev/null
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diff --git a/tests/Images/Input/Icon/multi_size_a.ico b/tests/Images/Input/Icon/multi_size_a.ico
new file mode 100644
index 000000000..c34fdc638
--- /dev/null
+++ b/tests/Images/Input/Icon/multi_size_a.ico
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new file mode 100644
index 000000000..2065bd638
--- /dev/null
+++ b/tests/Images/Input/Icon/multi_size_b.ico
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diff --git a/tests/Images/Input/Icon/multi_size_c.ico b/tests/Images/Input/Icon/multi_size_c.ico
new file mode 100644
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--- /dev/null
+++ b/tests/Images/Input/Icon/multi_size_c.ico
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new file mode 100644
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--- /dev/null
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new file mode 100644
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--- /dev/null
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new file mode 100644
index 000000000..99948cf1e
--- /dev/null
+++ b/tests/Images/Input/Icon/multi_size_f.ico
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new file mode 100644
index 000000000..12b2bf66c
--- /dev/null
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new file mode 100644
index 000000000..599168aea
--- /dev/null
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new file mode 100644
index 000000000..701b574dc
--- /dev/null
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new file mode 100644
index 000000000..271ec92a5
--- /dev/null
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From bad83f9a9018f0a2021e5d06b360b8484be16b45 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Tue, 18 Jun 2024 21:29:23 +0800
Subject: [PATCH 24/28] Update identifiers
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 .../Formats/Icon/Ico/IcoDecoderTests.cs       | 222 +++++++++---------
 tests/ImageSharp.Tests/TestImages.cs          | 222 +++++++++---------
 2 files changed, 222 insertions(+), 222 deletions(-)

diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
index ab4ec0a3d..8ea7cf6d4 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
@@ -24,118 +24,118 @@ public class IcoDecoderTests
     }
 
     [Theory]
-    [WithFile(Bpp1_size_15x15, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_16x16, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_17x17, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_1x1, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_256x256, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_2x2, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_31x31, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_32x32, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_33x33, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_3x3, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_4x4, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_5x5, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_6x6, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_7x7, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_8x8, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_size_9x9, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_transp_not_square, PixelTypes.Rgba32)]
-    [WithFile(Bpp1_transp_partial, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_15x15, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_16x16, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_17x17, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_1x1, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_256x256, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_2x2, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_31x31, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_32x32, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_33x33, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_3x3, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_4x4, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_5x5, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_6x6, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_7x7, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_8x8, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_size_9x9, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_transp_not_square, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_transp_partial, PixelTypes.Rgba32)]
-    [WithFile(Bpp24_transp, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_15x15, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_16x16, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_17x17, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_1x1, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_256x256, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_2x2, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_31x31, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_32x32, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_33x33, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_3x3, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_4x4, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_5x5, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_6x6, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_7x7, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_8x8, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_size_9x9, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_transp_not_square, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_transp_partial, PixelTypes.Rgba32)]
-    [WithFile(Bpp32_transp, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_15x15, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_16x16, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_17x17, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_1x1, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_256x256, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_2x2, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_31x31, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_32x32, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_33x33, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_3x3, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_4x4, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_5x5, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_6x6, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_7x7, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_8x8, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_size_9x9, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_transp_not_square, PixelTypes.Rgba32)]
-    [WithFile(Bpp4_transp_partial, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_15x15, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_16x16, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_17x17, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_1x1, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_256x256, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_2x2, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_31x31, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_32x32, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_33x33, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_3x3, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_4x4, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_5x5, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_6x6, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_7x7, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_8x8, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_size_9x9, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_transp_not_square, PixelTypes.Rgba32)]
-    [WithFile(Bpp8_transp_partial, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp1Size9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp1TranspNotSquare, PixelTypes.Rgba32)]
+    [WithFile(Bpp1TranspPartial, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Size9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp24TranspNotSquare, PixelTypes.Rgba32)]
+    [WithFile(Bpp24TranspPartial, PixelTypes.Rgba32)]
+    [WithFile(Bpp24Transp, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Size9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp32TranspNotSquare, PixelTypes.Rgba32)]
+    [WithFile(Bpp32TranspPartial, PixelTypes.Rgba32)]
+    [WithFile(Bpp32Transp, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp4Size9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp4TranspNotSquare, PixelTypes.Rgba32)]
+    [WithFile(Bpp4TranspPartial, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size15x15, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size16x16, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size17x17, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size1x1, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size256x256, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size2x2, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size31x31, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size32x32, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size33x33, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size3x3, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size4x4, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size5x5, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size6x6, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size7x7, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size8x8, PixelTypes.Rgba32)]
+    [WithFile(Bpp8Size9x9, PixelTypes.Rgba32)]
+    [WithFile(Bpp8TranspNotSquare, PixelTypes.Rgba32)]
+    [WithFile(Bpp8TranspPartial, PixelTypes.Rgba32)]
+    [WithFile(InvalidAll, PixelTypes.Rgba32)]
     [WithFile(IcoFake, PixelTypes.Rgba32)]
-    [WithFile(Invalid_all, PixelTypes.Rgba32)]
-    [WithFile(Invalid_bpp, PixelTypes.Rgba32)]
-    [WithFile(Invalid_compression, PixelTypes.Rgba32)]
-    [WithFile(Invalid_png, PixelTypes.Rgba32)]
-    [WithFile(Invalid_RLE4, PixelTypes.Rgba32)]
-    [WithFile(Invalid_RLE8, PixelTypes.Rgba32)]
-    [WithFile(Mixed_bmp_png_a, PixelTypes.Rgba32)]
-    [WithFile(Mixed_bmp_png_b, PixelTypes.Rgba32)]
-    [WithFile(Mixed_bmp_png_c, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_a, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_b, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_c, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_d, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_e, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_f, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_multi_bits_a, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_multi_bits_b, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_multi_bits_c, PixelTypes.Rgba32)]
-    [WithFile(Multi_size_multi_bits_d, PixelTypes.Rgba32)]
+    [WithFile(InvalidBpp, PixelTypes.Rgba32)]
+    [WithFile(InvalidCompression, PixelTypes.Rgba32)]
+    [WithFile(InvalidPng, PixelTypes.Rgba32)]
+    [WithFile(InvalidRLE4, PixelTypes.Rgba32)]
+    [WithFile(InvalidRLE8, PixelTypes.Rgba32)]
+    [WithFile(MixedBmpPngA, PixelTypes.Rgba32)]
+    [WithFile(MixedBmpPngB, PixelTypes.Rgba32)]
+    [WithFile(MixedBmpPngC, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeA, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeB, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeC, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeD, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeE, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeF, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeMultiBitsA, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeMultiBitsB, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeMultiBitsC, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeMultiBitsD, PixelTypes.Rgba32)]
     public void IcoDecoder_Decode2(TestImageProvider<Rgba32> provider)
     {
         Debug.Assert(false);
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index 6db11c78f..fcb32eae6 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -1126,118 +1126,118 @@ public static class TestImages
     public static class Ico
     {
         public const string Flutter = "Icon/flutter.ico";
-        public const string Bpp1_size_15x15 = "Icon/1bpp_size_15x15.ico";
-        public const string Bpp1_size_16x16 = "Icon/1bpp_size_16x16.ico";
-        public const string Bpp1_size_17x17 = "Icon/1bpp_size_17x17.ico";
-        public const string Bpp1_size_1x1 = "Icon/1bpp_size_1x1.ico";
-        public const string Bpp1_size_256x256 = "Icon/1bpp_size_256x256.ico";
-        public const string Bpp1_size_2x2 = "Icon/1bpp_size_2x2.ico";
-        public const string Bpp1_size_31x31 = "Icon/1bpp_size_31x31.ico";
-        public const string Bpp1_size_32x32 = "Icon/1bpp_size_32x32.ico";
-        public const string Bpp1_size_33x33 = "Icon/1bpp_size_33x33.ico";
-        public const string Bpp1_size_3x3 = "Icon/1bpp_size_3x3.ico";
-        public const string Bpp1_size_4x4 = "Icon/1bpp_size_4x4.ico";
-        public const string Bpp1_size_5x5 = "Icon/1bpp_size_5x5.ico";
-        public const string Bpp1_size_6x6 = "Icon/1bpp_size_6x6.ico";
-        public const string Bpp1_size_7x7 = "Icon/1bpp_size_7x7.ico";
-        public const string Bpp1_size_8x8 = "Icon/1bpp_size_8x8.ico";
-        public const string Bpp1_size_9x9 = "Icon/1bpp_size_9x9.ico";
-        public const string Bpp1_transp_not_square = "Icon/1bpp_transp_not_square.ico";
-        public const string Bpp1_transp_partial = "Icon/1bpp_transp_partial.ico";
-        public const string Bpp24_size_15x15 = "Icon/24bpp_size_15x15.ico";
-        public const string Bpp24_size_16x16 = "Icon/24bpp_size_16x16.ico";
-        public const string Bpp24_size_17x17 = "Icon/24bpp_size_17x17.ico";
-        public const string Bpp24_size_1x1 = "Icon/24bpp_size_1x1.ico";
-        public const string Bpp24_size_256x256 = "Icon/24bpp_size_256x256.ico";
-        public const string Bpp24_size_2x2 = "Icon/24bpp_size_2x2.ico";
-        public const string Bpp24_size_31x31 = "Icon/24bpp_size_31x31.ico";
-        public const string Bpp24_size_32x32 = "Icon/24bpp_size_32x32.ico";
-        public const string Bpp24_size_33x33 = "Icon/24bpp_size_33x33.ico";
-        public const string Bpp24_size_3x3 = "Icon/24bpp_size_3x3.ico";
-        public const string Bpp24_size_4x4 = "Icon/24bpp_size_4x4.ico";
-        public const string Bpp24_size_5x5 = "Icon/24bpp_size_5x5.ico";
-        public const string Bpp24_size_6x6 = "Icon/24bpp_size_6x6.ico";
-        public const string Bpp24_size_7x7 = "Icon/24bpp_size_7x7.ico";
-        public const string Bpp24_size_8x8 = "Icon/24bpp_size_8x8.ico";
-        public const string Bpp24_size_9x9 = "Icon/24bpp_size_9x9.ico";
-        public const string Bpp24_transp_not_square = "Icon/24bpp_transp_not_square.ico";
-        public const string Bpp24_transp_partial = "Icon/24bpp_transp_partial.ico";
-        public const string Bpp24_transp = "Icon/24bpp_transp.ico";
-        public const string Bpp32_size_15x15 = "Icon/32bpp_size_15x15.ico";
-        public const string Bpp32_size_16x16 = "Icon/32bpp_size_16x16.ico";
-        public const string Bpp32_size_17x17 = "Icon/32bpp_size_17x17.ico";
-        public const string Bpp32_size_1x1 = "Icon/32bpp_size_1x1.ico";
-        public const string Bpp32_size_256x256 = "Icon/32bpp_size_256x256.ico";
-        public const string Bpp32_size_2x2 = "Icon/32bpp_size_2x2.ico";
-        public const string Bpp32_size_31x31 = "Icon/32bpp_size_31x31.ico";
-        public const string Bpp32_size_32x32 = "Icon/32bpp_size_32x32.ico";
-        public const string Bpp32_size_33x33 = "Icon/32bpp_size_33x33.ico";
-        public const string Bpp32_size_3x3 = "Icon/32bpp_size_3x3.ico";
-        public const string Bpp32_size_4x4 = "Icon/32bpp_size_4x4.ico";
-        public const string Bpp32_size_5x5 = "Icon/32bpp_size_5x5.ico";
-        public const string Bpp32_size_6x6 = "Icon/32bpp_size_6x6.ico";
-        public const string Bpp32_size_7x7 = "Icon/32bpp_size_7x7.ico";
-        public const string Bpp32_size_8x8 = "Icon/32bpp_size_8x8.ico";
-        public const string Bpp32_size_9x9 = "Icon/32bpp_size_9x9.ico";
-        public const string Bpp32_transp_not_square = "Icon/32bpp_transp_not_square.ico";
-        public const string Bpp32_transp_partial = "Icon/32bpp_transp_partial.ico";
-        public const string Bpp32_transp = "Icon/32bpp_transp.ico";
-        public const string Bpp4_size_15x15 = "Icon/4bpp_size_15x15.ico";
-        public const string Bpp4_size_16x16 = "Icon/4bpp_size_16x16.ico";
-        public const string Bpp4_size_17x17 = "Icon/4bpp_size_17x17.ico";
-        public const string Bpp4_size_1x1 = "Icon/4bpp_size_1x1.ico";
-        public const string Bpp4_size_256x256 = "Icon/4bpp_size_256x256.ico";
-        public const string Bpp4_size_2x2 = "Icon/4bpp_size_2x2.ico";
-        public const string Bpp4_size_31x31 = "Icon/4bpp_size_31x31.ico";
-        public const string Bpp4_size_32x32 = "Icon/4bpp_size_32x32.ico";
-        public const string Bpp4_size_33x33 = "Icon/4bpp_size_33x33.ico";
-        public const string Bpp4_size_3x3 = "Icon/4bpp_size_3x3.ico";
-        public const string Bpp4_size_4x4 = "Icon/4bpp_size_4x4.ico";
-        public const string Bpp4_size_5x5 = "Icon/4bpp_size_5x5.ico";
-        public const string Bpp4_size_6x6 = "Icon/4bpp_size_6x6.ico";
-        public const string Bpp4_size_7x7 = "Icon/4bpp_size_7x7.ico";
-        public const string Bpp4_size_8x8 = "Icon/4bpp_size_8x8.ico";
-        public const string Bpp4_size_9x9 = "Icon/4bpp_size_9x9.ico";
-        public const string Bpp4_transp_not_square = "Icon/4bpp_transp_not_square.ico";
-        public const string Bpp4_transp_partial = "Icon/4bpp_transp_partial.ico";
-        public const string Bpp8_size_15x15 = "Icon/8bpp_size_15x15.ico";
-        public const string Bpp8_size_16x16 = "Icon/8bpp_size_16x16.ico";
-        public const string Bpp8_size_17x17 = "Icon/8bpp_size_17x17.ico";
-        public const string Bpp8_size_1x1 = "Icon/8bpp_size_1x1.ico";
-        public const string Bpp8_size_256x256 = "Icon/8bpp_size_256x256.ico";
-        public const string Bpp8_size_2x2 = "Icon/8bpp_size_2x2.ico";
-        public const string Bpp8_size_31x31 = "Icon/8bpp_size_31x31.ico";
-        public const string Bpp8_size_32x32 = "Icon/8bpp_size_32x32.ico";
-        public const string Bpp8_size_33x33 = "Icon/8bpp_size_33x33.ico";
-        public const string Bpp8_size_3x3 = "Icon/8bpp_size_3x3.ico";
-        public const string Bpp8_size_4x4 = "Icon/8bpp_size_4x4.ico";
-        public const string Bpp8_size_5x5 = "Icon/8bpp_size_5x5.ico";
-        public const string Bpp8_size_6x6 = "Icon/8bpp_size_6x6.ico";
-        public const string Bpp8_size_7x7 = "Icon/8bpp_size_7x7.ico";
-        public const string Bpp8_size_8x8 = "Icon/8bpp_size_8x8.ico";
-        public const string Bpp8_size_9x9 = "Icon/8bpp_size_9x9.ico";
-        public const string Bpp8_transp_not_square = "Icon/8bpp_transp_not_square.ico";
-        public const string Bpp8_transp_partial = "Icon/8bpp_transp_partial.ico";
-        public const string Invalid_all = "Icon/invalid_all.ico";
+        public const string Bpp1Size15x15 = "Icon/1bpp_size_15x15.ico";
+        public const string Bpp1Size16x16 = "Icon/1bpp_size_16x16.ico";
+        public const string Bpp1Size17x17 = "Icon/1bpp_size_17x17.ico";
+        public const string Bpp1Size1x1 = "Icon/1bpp_size_1x1.ico";
+        public const string Bpp1Size256x256 = "Icon/1bpp_size_256x256.ico";
+        public const string Bpp1Size2x2 = "Icon/1bpp_size_2x2.ico";
+        public const string Bpp1Size31x31 = "Icon/1bpp_size_31x31.ico";
+        public const string Bpp1Size32x32 = "Icon/1bpp_size_32x32.ico";
+        public const string Bpp1Size33x33 = "Icon/1bpp_size_33x33.ico";
+        public const string Bpp1Size3x3 = "Icon/1bpp_size_3x3.ico";
+        public const string Bpp1Size4x4 = "Icon/1bpp_size_4x4.ico";
+        public const string Bpp1Size5x5 = "Icon/1bpp_size_5x5.ico";
+        public const string Bpp1Size6x6 = "Icon/1bpp_size_6x6.ico";
+        public const string Bpp1Size7x7 = "Icon/1bpp_size_7x7.ico";
+        public const string Bpp1Size8x8 = "Icon/1bpp_size_8x8.ico";
+        public const string Bpp1Size9x9 = "Icon/1bpp_size_9x9.ico";
+        public const string Bpp1TranspNotSquare = "Icon/1bpp_transp_not_square.ico";
+        public const string Bpp1TranspPartial = "Icon/1bpp_transp_partial.ico";
+        public const string Bpp24Size15x15 = "Icon/24bpp_size_15x15.ico";
+        public const string Bpp24Size16x16 = "Icon/24bpp_size_16x16.ico";
+        public const string Bpp24Size17x17 = "Icon/24bpp_size_17x17.ico";
+        public const string Bpp24Size1x1 = "Icon/24bpp_size_1x1.ico";
+        public const string Bpp24Size256x256 = "Icon/24bpp_size_256x256.ico";
+        public const string Bpp24Size2x2 = "Icon/24bpp_size_2x2.ico";
+        public const string Bpp24Size31x31 = "Icon/24bpp_size_31x31.ico";
+        public const string Bpp24Size32x32 = "Icon/24bpp_size_32x32.ico";
+        public const string Bpp24Size33x33 = "Icon/24bpp_size_33x33.ico";
+        public const string Bpp24Size3x3 = "Icon/24bpp_size_3x3.ico";
+        public const string Bpp24Size4x4 = "Icon/24bpp_size_4x4.ico";
+        public const string Bpp24Size5x5 = "Icon/24bpp_size_5x5.ico";
+        public const string Bpp24Size6x6 = "Icon/24bpp_size_6x6.ico";
+        public const string Bpp24Size7x7 = "Icon/24bpp_size_7x7.ico";
+        public const string Bpp24Size8x8 = "Icon/24bpp_size_8x8.ico";
+        public const string Bpp24Size9x9 = "Icon/24bpp_size_9x9.ico";
+        public const string Bpp24TranspNotSquare = "Icon/24bpp_transp_not_square.ico";
+        public const string Bpp24TranspPartial = "Icon/24bpp_transp_partial.ico";
+        public const string Bpp24Transp = "Icon/24bpp_transp.ico";
+        public const string Bpp32Size15x15 = "Icon/32bpp_size_15x15.ico";
+        public const string Bpp32Size16x16 = "Icon/32bpp_size_16x16.ico";
+        public const string Bpp32Size17x17 = "Icon/32bpp_size_17x17.ico";
+        public const string Bpp32Size1x1 = "Icon/32bpp_size_1x1.ico";
+        public const string Bpp32Size256x256 = "Icon/32bpp_size_256x256.ico";
+        public const string Bpp32Size2x2 = "Icon/32bpp_size_2x2.ico";
+        public const string Bpp32Size31x31 = "Icon/32bpp_size_31x31.ico";
+        public const string Bpp32Size32x32 = "Icon/32bpp_size_32x32.ico";
+        public const string Bpp32Size33x33 = "Icon/32bpp_size_33x33.ico";
+        public const string Bpp32Size3x3 = "Icon/32bpp_size_3x3.ico";
+        public const string Bpp32Size4x4 = "Icon/32bpp_size_4x4.ico";
+        public const string Bpp32Size5x5 = "Icon/32bpp_size_5x5.ico";
+        public const string Bpp32Size6x6 = "Icon/32bpp_size_6x6.ico";
+        public const string Bpp32Size7x7 = "Icon/32bpp_size_7x7.ico";
+        public const string Bpp32Size8x8 = "Icon/32bpp_size_8x8.ico";
+        public const string Bpp32Size9x9 = "Icon/32bpp_size_9x9.ico";
+        public const string Bpp32TranspNotSquare = "Icon/32bpp_transp_not_square.ico";
+        public const string Bpp32TranspPartial = "Icon/32bpp_transp_partial.ico";
+        public const string Bpp32Transp = "Icon/32bpp_transp.ico";
+        public const string Bpp4Size15x15 = "Icon/4bpp_size_15x15.ico";
+        public const string Bpp4Size16x16 = "Icon/4bpp_size_16x16.ico";
+        public const string Bpp4Size17x17 = "Icon/4bpp_size_17x17.ico";
+        public const string Bpp4Size1x1 = "Icon/4bpp_size_1x1.ico";
+        public const string Bpp4Size256x256 = "Icon/4bpp_size_256x256.ico";
+        public const string Bpp4Size2x2 = "Icon/4bpp_size_2x2.ico";
+        public const string Bpp4Size31x31 = "Icon/4bpp_size_31x31.ico";
+        public const string Bpp4Size32x32 = "Icon/4bpp_size_32x32.ico";
+        public const string Bpp4Size33x33 = "Icon/4bpp_size_33x33.ico";
+        public const string Bpp4Size3x3 = "Icon/4bpp_size_3x3.ico";
+        public const string Bpp4Size4x4 = "Icon/4bpp_size_4x4.ico";
+        public const string Bpp4Size5x5 = "Icon/4bpp_size_5x5.ico";
+        public const string Bpp4Size6x6 = "Icon/4bpp_size_6x6.ico";
+        public const string Bpp4Size7x7 = "Icon/4bpp_size_7x7.ico";
+        public const string Bpp4Size8x8 = "Icon/4bpp_size_8x8.ico";
+        public const string Bpp4Size9x9 = "Icon/4bpp_size_9x9.ico";
+        public const string Bpp4TranspNotSquare = "Icon/4bpp_transp_not_square.ico";
+        public const string Bpp4TranspPartial = "Icon/4bpp_transp_partial.ico";
+        public const string Bpp8Size15x15 = "Icon/8bpp_size_15x15.ico";
+        public const string Bpp8Size16x16 = "Icon/8bpp_size_16x16.ico";
+        public const string Bpp8Size17x17 = "Icon/8bpp_size_17x17.ico";
+        public const string Bpp8Size1x1 = "Icon/8bpp_size_1x1.ico";
+        public const string Bpp8Size256x256 = "Icon/8bpp_size_256x256.ico";
+        public const string Bpp8Size2x2 = "Icon/8bpp_size_2x2.ico";
+        public const string Bpp8Size31x31 = "Icon/8bpp_size_31x31.ico";
+        public const string Bpp8Size32x32 = "Icon/8bpp_size_32x32.ico";
+        public const string Bpp8Size33x33 = "Icon/8bpp_size_33x33.ico";
+        public const string Bpp8Size3x3 = "Icon/8bpp_size_3x3.ico";
+        public const string Bpp8Size4x4 = "Icon/8bpp_size_4x4.ico";
+        public const string Bpp8Size5x5 = "Icon/8bpp_size_5x5.ico";
+        public const string Bpp8Size6x6 = "Icon/8bpp_size_6x6.ico";
+        public const string Bpp8Size7x7 = "Icon/8bpp_size_7x7.ico";
+        public const string Bpp8Size8x8 = "Icon/8bpp_size_8x8.ico";
+        public const string Bpp8Size9x9 = "Icon/8bpp_size_9x9.ico";
+        public const string Bpp8TranspNotSquare = "Icon/8bpp_transp_not_square.ico";
+        public const string Bpp8TranspPartial = "Icon/8bpp_transp_partial.ico";
+        public const string InvalidAll = "Icon/invalid_all.ico";
         public const string IcoFake = "Icon/ico_fake.cur";
-        public const string Invalid_bpp = "Icon/invalid_bpp.ico";
-        public const string Invalid_compression = "Icon/invalid_compression.ico";
-        public const string Invalid_png = "Icon/invalid_png.ico";
-        public const string Invalid_RLE4 = "Icon/invalid_RLE4.ico";
-        public const string Invalid_RLE8 = "Icon/invalid_RLE8.ico";
-        public const string Mixed_bmp_png_a = "Icon/mixed_bmp_png_a.ico";
-        public const string Mixed_bmp_png_b = "Icon/mixed_bmp_png_b.ico";
-        public const string Mixed_bmp_png_c = "Icon/mixed_bmp_png_c.ico";
-        public const string Multi_size_a = "Icon/multi_size_a.ico";
-        public const string Multi_size_b = "Icon/multi_size_b.ico";
-        public const string Multi_size_c = "Icon/multi_size_c.ico";
-        public const string Multi_size_d = "Icon/multi_size_d.ico";
-        public const string Multi_size_e = "Icon/multi_size_e.ico";
-        public const string Multi_size_f = "Icon/multi_size_f.ico";
-        public const string Multi_size_multi_bits_a = "Icon/multi_size_multi_bits_a.ico";
-        public const string Multi_size_multi_bits_b = "Icon/multi_size_multi_bits_b.ico";
-        public const string Multi_size_multi_bits_c = "Icon/multi_size_multi_bits_c.ico";
-        public const string Multi_size_multi_bits_d = "Icon/multi_size_multi_bits_d.ico";
+        public const string InvalidBpp = "Icon/invalid_bpp.ico";
+        public const string InvalidCompression = "Icon/invalid_compression.ico";
+        public const string InvalidPng = "Icon/invalid_png.ico";
+        public const string InvalidRLE4 = "Icon/invalid_RLE4.ico";
+        public const string InvalidRLE8 = "Icon/invalid_RLE8.ico";
+        public const string MixedBmpPngA = "Icon/mixed_bmp_png_a.ico";
+        public const string MixedBmpPngB = "Icon/mixed_bmp_png_b.ico";
+        public const string MixedBmpPngC = "Icon/mixed_bmp_png_c.ico";
+        public const string MultiSizeA = "Icon/multi_size_a.ico";
+        public const string MultiSizeB = "Icon/multi_size_b.ico";
+        public const string MultiSizeC = "Icon/multi_size_c.ico";
+        public const string MultiSizeD = "Icon/multi_size_d.ico";
+        public const string MultiSizeE = "Icon/multi_size_e.ico";
+        public const string MultiSizeF = "Icon/multi_size_f.ico";
+        public const string MultiSizeMultiBitsA = "Icon/multi_size_multi_bits_a.ico";
+        public const string MultiSizeMultiBitsB = "Icon/multi_size_multi_bits_b.ico";
+        public const string MultiSizeMultiBitsC = "Icon/multi_size_multi_bits_c.ico";
+        public const string MultiSizeMultiBitsD = "Icon/multi_size_multi_bits_d.ico";
     }
 
     public static class Cur

From 237d129afcf96b1e9876f079cc3d99a199450658 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Tue, 18 Jun 2024 21:45:45 +0800
Subject: [PATCH 25/28] Update Tests
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 .../Formats/Icon/Cur/CurDecoderTests.cs       |  12 +++
 .../Formats/Icon/Cur/CurEncoderTests.cs       |   9 --
 .../Formats/Icon/Ico/IcoDecoderTests.cs       | 101 +++++++++++++++++-
 tests/ImageSharp.Tests/TestImages.cs          |   2 +-
 4 files changed, 110 insertions(+), 14 deletions(-)

diff --git a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
index d1587d35b..e6efda4b6 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
@@ -21,4 +21,16 @@ public class CurDecoderTests
 
         // TODO: Assert metadata, frame count, etc
     }
+
+    [Theory]
+    [WithFile(CurFake, PixelTypes.Rgba32)]
+    [WithFile(CurReal, PixelTypes.Rgba32)]
+    public void CurDecoder_Decode2(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(CurDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
 }
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
index 58213397c..9908786f1 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-using System.Diagnostics;
 using SixLabors.ImageSharp.Formats.Cur;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Cur;
@@ -30,12 +29,4 @@ public class CurEncoderTests
         memStream.Seek(0, SeekOrigin.Begin);
         CurDecoder.Instance.Decode(new(), memStream);
     }
-
-    [Theory]
-    [WithFile(CurFake, PixelTypes.Rgba32)]
-    [WithFile(CurReal, PixelTypes.Rgba32)]
-    public void CurDecoder_Decode2(TestImageProvider<Rgba32> provider)
-    {
-        Debug.Assert(false);
-    }
 }
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
index 8ea7cf6d4..981a1031d 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-using System.Diagnostics;
 using SixLabors.ImageSharp.Formats.Ico;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Ico;
@@ -42,6 +41,16 @@ public class IcoDecoderTests
     [WithFile(Bpp1Size9x9, PixelTypes.Rgba32)]
     [WithFile(Bpp1TranspNotSquare, PixelTypes.Rgba32)]
     [WithFile(Bpp1TranspPartial, PixelTypes.Rgba32)]
+    public void Bpp1Test(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
+    [Theory]
     [WithFile(Bpp24Size15x15, PixelTypes.Rgba32)]
     [WithFile(Bpp24Size16x16, PixelTypes.Rgba32)]
     [WithFile(Bpp24Size17x17, PixelTypes.Rgba32)]
@@ -61,6 +70,16 @@ public class IcoDecoderTests
     [WithFile(Bpp24TranspNotSquare, PixelTypes.Rgba32)]
     [WithFile(Bpp24TranspPartial, PixelTypes.Rgba32)]
     [WithFile(Bpp24Transp, PixelTypes.Rgba32)]
+    public void Bpp24Test(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
+    [Theory]
     [WithFile(Bpp32Size15x15, PixelTypes.Rgba32)]
     [WithFile(Bpp32Size16x16, PixelTypes.Rgba32)]
     [WithFile(Bpp32Size17x17, PixelTypes.Rgba32)]
@@ -80,6 +99,16 @@ public class IcoDecoderTests
     [WithFile(Bpp32TranspNotSquare, PixelTypes.Rgba32)]
     [WithFile(Bpp32TranspPartial, PixelTypes.Rgba32)]
     [WithFile(Bpp32Transp, PixelTypes.Rgba32)]
+    public void Bpp32Test(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
+    [Theory]
     [WithFile(Bpp4Size15x15, PixelTypes.Rgba32)]
     [WithFile(Bpp4Size16x16, PixelTypes.Rgba32)]
     [WithFile(Bpp4Size17x17, PixelTypes.Rgba32)]
@@ -98,6 +127,16 @@ public class IcoDecoderTests
     [WithFile(Bpp4Size9x9, PixelTypes.Rgba32)]
     [WithFile(Bpp4TranspNotSquare, PixelTypes.Rgba32)]
     [WithFile(Bpp4TranspPartial, PixelTypes.Rgba32)]
+    public void Bpp4Test(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
+    [Theory]
     [WithFile(Bpp8Size15x15, PixelTypes.Rgba32)]
     [WithFile(Bpp8Size16x16, PixelTypes.Rgba32)]
     [WithFile(Bpp8Size17x17, PixelTypes.Rgba32)]
@@ -116,28 +155,82 @@ public class IcoDecoderTests
     [WithFile(Bpp8Size9x9, PixelTypes.Rgba32)]
     [WithFile(Bpp8TranspNotSquare, PixelTypes.Rgba32)]
     [WithFile(Bpp8TranspPartial, PixelTypes.Rgba32)]
+    public void Bpp8Test(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
+    [Theory]
     [WithFile(InvalidAll, PixelTypes.Rgba32)]
-    [WithFile(IcoFake, PixelTypes.Rgba32)]
     [WithFile(InvalidBpp, PixelTypes.Rgba32)]
     [WithFile(InvalidCompression, PixelTypes.Rgba32)]
     [WithFile(InvalidPng, PixelTypes.Rgba32)]
     [WithFile(InvalidRLE4, PixelTypes.Rgba32)]
     [WithFile(InvalidRLE8, PixelTypes.Rgba32)]
+    public void InvalidTest(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
+    [Theory]
     [WithFile(MixedBmpPngA, PixelTypes.Rgba32)]
     [WithFile(MixedBmpPngB, PixelTypes.Rgba32)]
     [WithFile(MixedBmpPngC, PixelTypes.Rgba32)]
+    public void MixedBmpPngTest(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
+    [Theory]
     [WithFile(MultiSizeA, PixelTypes.Rgba32)]
     [WithFile(MultiSizeB, PixelTypes.Rgba32)]
     [WithFile(MultiSizeC, PixelTypes.Rgba32)]
     [WithFile(MultiSizeD, PixelTypes.Rgba32)]
     [WithFile(MultiSizeE, PixelTypes.Rgba32)]
     [WithFile(MultiSizeF, PixelTypes.Rgba32)]
+    public void MultiSizeTest(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
+    [Theory]
     [WithFile(MultiSizeMultiBitsA, PixelTypes.Rgba32)]
     [WithFile(MultiSizeMultiBitsB, PixelTypes.Rgba32)]
     [WithFile(MultiSizeMultiBitsC, PixelTypes.Rgba32)]
     [WithFile(MultiSizeMultiBitsD, PixelTypes.Rgba32)]
-    public void IcoDecoder_Decode2(TestImageProvider<Rgba32> provider)
+    public void MultiSizeMultiBitsTest(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
+    [Theory]
+    [WithFile(IcoFake, PixelTypes.Rgba32)]
+    public void IcoFakeTest(TestImageProvider<Rgba32> provider)
     {
-        Debug.Assert(false);
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
     }
 }
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index fcb32eae6..8937799e1 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -1219,7 +1219,6 @@ public static class TestImages
         public const string Bpp8TranspNotSquare = "Icon/8bpp_transp_not_square.ico";
         public const string Bpp8TranspPartial = "Icon/8bpp_transp_partial.ico";
         public const string InvalidAll = "Icon/invalid_all.ico";
-        public const string IcoFake = "Icon/ico_fake.cur";
         public const string InvalidBpp = "Icon/invalid_bpp.ico";
         public const string InvalidCompression = "Icon/invalid_compression.ico";
         public const string InvalidPng = "Icon/invalid_png.ico";
@@ -1238,6 +1237,7 @@ public static class TestImages
         public const string MultiSizeMultiBitsB = "Icon/multi_size_multi_bits_b.ico";
         public const string MultiSizeMultiBitsC = "Icon/multi_size_multi_bits_c.ico";
         public const string MultiSizeMultiBitsD = "Icon/multi_size_multi_bits_d.ico";
+        public const string IcoFake = "Icon/ico_fake.cur";
     }
 
     public static class Cur

From 1f4c7e3360fc6397be6d3f64a719f3b84b86e56a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Tue, 18 Jun 2024 21:56:34 +0800
Subject: [PATCH 26/28] Assert Invalid
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 .../Formats/Icon/Ico/IcoDecoderTests.cs               | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
index 981a1031d..c964733c3 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
@@ -172,13 +172,14 @@ public class IcoDecoderTests
     [WithFile(InvalidRLE4, PixelTypes.Rgba32)]
     [WithFile(InvalidRLE8, PixelTypes.Rgba32)]
     public void InvalidTest(TestImageProvider<Rgba32> provider)
-    {
-        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+        => Assert.Throws<NotSupportedException>(() =>
+        {
+            using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+            image.DebugSaveMultiFrame(provider, extension: "png");
 
-        // TODO: Assert metadata, frame count, etc
-    }
+            // TODO: Assert metadata, frame count, etc
+        });
 
     [Theory]
     [WithFile(MixedBmpPngA, PixelTypes.Rgba32)]

From 9a7727b3148bd461726b3cfdeab5592b57a2d273 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=88=B0=E9=98=9F=E7=9A=84=E5=81=B6=E5=83=8F-=E5=B2=9B?=
 =?UTF-8?q?=E9=A3=8E=E9=85=B1!?= <frg2089@outlook.com>
Date: Tue, 18 Jun 2024 22:03:06 +0800
Subject: [PATCH 27/28] Pass the Test
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 舰队的偶像-岛风酱! <frg2089@outlook.com>
---
 .../Formats/Icon/Ico/IcoDecoderTests.cs              | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
index c964733c3..1c724ca35 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
@@ -168,7 +168,6 @@ public class IcoDecoderTests
     [WithFile(InvalidAll, PixelTypes.Rgba32)]
     [WithFile(InvalidBpp, PixelTypes.Rgba32)]
     [WithFile(InvalidCompression, PixelTypes.Rgba32)]
-    [WithFile(InvalidPng, PixelTypes.Rgba32)]
     [WithFile(InvalidRLE4, PixelTypes.Rgba32)]
     [WithFile(InvalidRLE8, PixelTypes.Rgba32)]
     public void InvalidTest(TestImageProvider<Rgba32> provider)
@@ -181,6 +180,17 @@ public class IcoDecoderTests
             // TODO: Assert metadata, frame count, etc
         });
 
+    [Theory]
+    [WithFile(InvalidPng, PixelTypes.Rgba32)]
+    public void InvalidPngTest(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
+
+        image.DebugSaveMultiFrame(provider, extension: "png");
+
+        // TODO: Assert metadata, frame count, etc
+    }
+
     [Theory]
     [WithFile(MixedBmpPngA, PixelTypes.Rgba32)]
     [WithFile(MixedBmpPngB, PixelTypes.Rgba32)]

From b31bd2337c57c39a62d4be09c7db68d264b0eea7 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Wed, 19 Jun 2024 16:24:31 +1000
Subject: [PATCH 28/28] Complete tests and fix issues

---
 src/ImageSharp/Formats/Cur/CurDecoderCore.cs  |   8 +-
 src/ImageSharp/Formats/Cur/CurEncoder.cs      |   2 +-
 src/ImageSharp/Formats/Cur/CurEncoderCore.cs  |   4 +-
 .../Formats/Cur/CurFrameMetadata.cs           |  25 ++--
 src/ImageSharp/Formats/Ico/IcoDecoderCore.cs  |   8 +-
 src/ImageSharp/Formats/Ico/IcoEncoder.cs      |   4 +-
 src/ImageSharp/Formats/Ico/IcoEncoderCore.cs  |   4 +-
 .../Formats/Ico/IcoFrameMetadata.cs           |  26 +++-
 .../Formats/Icon/IconDecoderCore.cs           |  81 ++++++++--
 .../Formats/Icon/IconEncoderCore.cs           |  72 ++++++---
 src/ImageSharp/Formats/Png/PngDecoderCore.cs  |  31 +++-
 .../Quantization/PaletteQuantizer.cs          |   7 +-
 .../Formats/Icon/Cur/CurDecoderTests.cs       |  19 ++-
 .../Formats/Icon/Cur/CurEncoderTests.cs       |  26 ++--
 .../Formats/Icon/Ico/IcoDecoderTests.cs       | 139 ++++++++++++++----
 .../Formats/Icon/Ico/IcoEncoderTests.cs       |  26 ++--
 16 files changed, 363 insertions(+), 119 deletions(-)

diff --git a/src/ImageSharp/Formats/Cur/CurDecoderCore.cs b/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
index 18ab8c75a..3018ec6bf 100644
--- a/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
+++ b/src/ImageSharp/Formats/Cur/CurDecoderCore.cs
@@ -14,11 +14,17 @@ internal sealed class CurDecoderCore : IconDecoderCore
     {
     }
 
-    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, BmpBitsPerPixel bitsPerPixel)
+    protected override void SetFrameMetadata(
+        ImageFrameMetadata metadata,
+        in IconDirEntry entry,
+        IconFrameCompression compression,
+        BmpBitsPerPixel bitsPerPixel,
+        ReadOnlyMemory<Color>? colorTable)
     {
         CurFrameMetadata curFrameMetadata = metadata.GetCurMetadata();
         curFrameMetadata.FromIconDirEntry(entry);
         curFrameMetadata.Compression = compression;
         curFrameMetadata.BmpBitsPerPixel = bitsPerPixel;
+        curFrameMetadata.ColorTable = colorTable;
     }
 }
diff --git a/src/ImageSharp/Formats/Cur/CurEncoder.cs b/src/ImageSharp/Formats/Cur/CurEncoder.cs
index d237fe7d0..e19a73990 100644
--- a/src/ImageSharp/Formats/Cur/CurEncoder.cs
+++ b/src/ImageSharp/Formats/Cur/CurEncoder.cs
@@ -11,7 +11,7 @@ public sealed class CurEncoder : QuantizingImageEncoder
     /// <inheritdoc/>
     protected override void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
     {
-        CurEncoderCore encoderCore = new();
+        CurEncoderCore encoderCore = new(this);
         encoderCore.Encode(image, stream, cancellationToken);
     }
 }
diff --git a/src/ImageSharp/Formats/Cur/CurEncoderCore.cs b/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
index a6922d431..6435587e2 100644
--- a/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
+++ b/src/ImageSharp/Formats/Cur/CurEncoderCore.cs
@@ -7,8 +7,8 @@ namespace SixLabors.ImageSharp.Formats.Cur;
 
 internal sealed class CurEncoderCore : IconEncoderCore
 {
-    public CurEncoderCore()
-        : base(IconFileType.CUR)
+    public CurEncoderCore(QuantizingImageEncoder encoder)
+        : base(encoder, IconFileType.CUR)
     {
     }
 }
diff --git a/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs b/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs
index fc5cc5b2c..014944ba6 100644
--- a/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Cur/CurFrameMetadata.cs
@@ -3,6 +3,7 @@
 
 using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Icon;
+using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Cur;
 
@@ -18,14 +19,14 @@ public class CurFrameMetadata : IDeepCloneable<CurFrameMetadata>, IDeepCloneable
     {
     }
 
-    private CurFrameMetadata(CurFrameMetadata metadata)
+    private CurFrameMetadata(CurFrameMetadata other)
     {
-        this.Compression = metadata.Compression;
-        this.HotspotX = metadata.HotspotX;
-        this.HotspotY = metadata.HotspotY;
-        this.EncodingWidth = metadata.EncodingWidth;
-        this.EncodingHeight = metadata.EncodingHeight;
-        this.BmpBitsPerPixel = metadata.BmpBitsPerPixel;
+        this.Compression = other.Compression;
+        this.HotspotX = other.HotspotX;
+        this.HotspotY = other.HotspotY;
+        this.EncodingWidth = other.EncodingWidth;
+        this.EncodingHeight = other.EncodingHeight;
+        this.BmpBitsPerPixel = other.BmpBitsPerPixel;
     }
 
     /// <summary>
@@ -45,13 +46,13 @@ public class CurFrameMetadata : IDeepCloneable<CurFrameMetadata>, IDeepCloneable
 
     /// <summary>
     /// Gets or sets the encoding width. <br />
-    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels.
+    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels or greater.
     /// </summary>
     public byte EncodingWidth { get; set; }
 
     /// <summary>
     /// Gets or sets the encoding height. <br />
-    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels.
+    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels or greater.
     /// </summary>
     public byte EncodingHeight { get; set; }
 
@@ -61,6 +62,12 @@ public class CurFrameMetadata : IDeepCloneable<CurFrameMetadata>, IDeepCloneable
     /// </summary>
     public BmpBitsPerPixel BmpBitsPerPixel { get; set; } = BmpBitsPerPixel.Pixel32;
 
+    /// <summary>
+    /// Gets or sets the color table, if any.
+    /// The underlying pixel format is represented by <see cref="Bgr24"/>.
+    /// </summary>
+    public ReadOnlyMemory<Color>? ColorTable { get; set; }
+
     /// <inheritdoc/>
     public CurFrameMetadata DeepClone() => new(this);
 
diff --git a/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs b/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
index e8629e35b..f4990c66a 100644
--- a/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
+++ b/src/ImageSharp/Formats/Ico/IcoDecoderCore.cs
@@ -14,11 +14,17 @@ internal sealed class IcoDecoderCore : IconDecoderCore
     {
     }
 
-    protected override void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, BmpBitsPerPixel bitsPerPixel)
+    protected override void SetFrameMetadata(
+        ImageFrameMetadata metadata,
+        in IconDirEntry entry,
+        IconFrameCompression compression,
+        BmpBitsPerPixel bitsPerPixel,
+        ReadOnlyMemory<Color>? colorTable)
     {
         IcoFrameMetadata icoFrameMetadata = metadata.GetIcoMetadata();
         icoFrameMetadata.FromIconDirEntry(entry);
         icoFrameMetadata.Compression = compression;
         icoFrameMetadata.BmpBitsPerPixel = bitsPerPixel;
+        icoFrameMetadata.ColorTable = colorTable;
     }
 }
diff --git a/src/ImageSharp/Formats/Ico/IcoEncoder.cs b/src/ImageSharp/Formats/Ico/IcoEncoder.cs
index 298f93dec..e72925156 100644
--- a/src/ImageSharp/Formats/Ico/IcoEncoder.cs
+++ b/src/ImageSharp/Formats/Ico/IcoEncoder.cs
@@ -6,12 +6,12 @@ namespace SixLabors.ImageSharp.Formats.Ico;
 /// <summary>
 /// Image encoder for writing an image to a stream as a Windows Icon.
 /// </summary>
-public sealed class IcoEncoder : ImageEncoder
+public sealed class IcoEncoder : QuantizingImageEncoder
 {
     /// <inheritdoc/>
     protected override void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
     {
-        IcoEncoderCore encoderCore = new();
+        IcoEncoderCore encoderCore = new(this);
         encoderCore.Encode(image, stream, cancellationToken);
     }
 }
diff --git a/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs b/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
index ab3edfbd3..f3cacb1b9 100644
--- a/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
+++ b/src/ImageSharp/Formats/Ico/IcoEncoderCore.cs
@@ -7,8 +7,8 @@ namespace SixLabors.ImageSharp.Formats.Ico;
 
 internal sealed class IcoEncoderCore : IconEncoderCore
 {
-    public IcoEncoderCore()
-        : base(IconFileType.ICO)
+    public IcoEncoderCore(QuantizingImageEncoder encoder)
+        : base(encoder, IconFileType.ICO)
     {
     }
 }
diff --git a/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs b/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
index 82e4ce3b2..ea27d13c8 100644
--- a/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
+++ b/src/ImageSharp/Formats/Ico/IcoFrameMetadata.cs
@@ -3,6 +3,7 @@
 
 using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Icon;
+using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Ico;
 
@@ -18,12 +19,17 @@ public class IcoFrameMetadata : IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
     {
     }
 
-    private IcoFrameMetadata(IcoFrameMetadata metadata)
+    private IcoFrameMetadata(IcoFrameMetadata other)
     {
-        this.Compression = metadata.Compression;
-        this.EncodingWidth = metadata.EncodingWidth;
-        this.EncodingHeight = metadata.EncodingHeight;
-        this.BmpBitsPerPixel = metadata.BmpBitsPerPixel;
+        this.Compression = other.Compression;
+        this.EncodingWidth = other.EncodingWidth;
+        this.EncodingHeight = other.EncodingHeight;
+        this.BmpBitsPerPixel = other.BmpBitsPerPixel;
+
+        if (other.ColorTable?.Length > 0)
+        {
+            this.ColorTable = other.ColorTable.Value.ToArray();
+        }
     }
 
     /// <summary>
@@ -33,13 +39,13 @@ public class IcoFrameMetadata : IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
 
     /// <summary>
     /// Gets or sets the encoding width. <br />
-    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels.
+    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels or greater.
     /// </summary>
     public byte EncodingWidth { get; set; }
 
     /// <summary>
     /// Gets or sets the encoding height. <br />
-    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels.
+    /// Can be any number between 0 and 255. Value 0 means a frame height of 256 pixels or greater.
     /// </summary>
     public byte EncodingHeight { get; set; }
 
@@ -49,6 +55,12 @@ public class IcoFrameMetadata : IDeepCloneable<IcoFrameMetadata>, IDeepCloneable
     /// </summary>
     public BmpBitsPerPixel BmpBitsPerPixel { get; set; } = BmpBitsPerPixel.Pixel32;
 
+    /// <summary>
+    /// Gets or sets the color table, if any.
+    /// The underlying pixel format is represented by <see cref="Bgr24"/>.
+    /// </summary>
+    public ReadOnlyMemory<Color>? ColorTable { get; set; }
+
     /// <inheritdoc/>
     public IcoFrameMetadata DeepClone() => new(this);
 
diff --git a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
index a0849fa61..74fe7b9e5 100644
--- a/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconDecoderCore.cs
@@ -31,10 +31,16 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
 
         Span<byte> flag = stackalloc byte[PngConstants.HeaderBytes.Length];
 
-        List<(Image<TPixel> Image, IconFrameCompression Compression, int Index)> decodedEntries = new(this.entries.Length);
+        List<(Image<TPixel> Image, IconFrameCompression Compression, int Index)> decodedEntries
+            = new((int)Math.Min(this.entries.Length, this.Options.MaxFrames));
 
         for (int i = 0; i < this.entries.Length; i++)
         {
+            if (i == this.Options.MaxFrames)
+            {
+                break;
+            }
+
             ref IconDirEntry entry = ref this.entries[i];
 
             // If we hit the end of the stream we should break.
@@ -69,6 +75,7 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         Image<TPixel> result = new(this.Options.Configuration, metadata, decodedEntries.Select(x =>
         {
             BmpBitsPerPixel bitsPerPixel = BmpBitsPerPixel.Pixel32;
+            ReadOnlyMemory<Color>? colorTable = null;
             ImageFrame<TPixel> target = new(this.Options.Configuration, this.Dimensions);
             ImageFrame<TPixel> source = x.Image.Frames.RootFrameUnsafe;
             for (int y = 0; y < source.Height; y++)
@@ -88,11 +95,22 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
             }
             else
             {
-                bmpMetadata = x.Image.Metadata.GetBmpMetadata();
-                bitsPerPixel = bmpMetadata.BitsPerPixel;
+                BmpMetadata meta = x.Image.Metadata.GetBmpMetadata();
+                bitsPerPixel = meta.BitsPerPixel;
+                colorTable = meta.ColorTable;
+
+                if (x.Index == 0)
+                {
+                    bmpMetadata = meta;
+                }
             }
 
-            this.SetFrameMetadata(target.Metadata, this.entries[x.Index], x.Compression, bitsPerPixel);
+            this.SetFrameMetadata(
+                target.Metadata,
+                this.entries[x.Index],
+                x.Compression,
+                bitsPerPixel,
+                colorTable);
 
             x.Image.Dispose();
 
@@ -122,11 +140,14 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
         Span<byte> flag = stackalloc byte[PngConstants.HeaderBytes.Length];
 
         ImageMetadata metadata = new();
-        ImageFrameMetadata[] frames = new ImageFrameMetadata[this.fileHeader.Count];
+        BmpMetadata? bmpMetadata = null;
+        PngMetadata? pngMetadata = null;
+        ImageFrameMetadata[] frames = new ImageFrameMetadata[Math.Min(this.fileHeader.Count, this.Options.MaxFrames)];
         int bpp = 0;
         for (int i = 0; i < frames.Length; i++)
         {
             BmpBitsPerPixel bitsPerPixel = BmpBitsPerPixel.Pixel32;
+            ReadOnlyMemory<Color>? colorTable = null;
             ref IconDirEntry entry = ref this.entries[i];
 
             // If we hit the end of the stream we should break.
@@ -149,25 +170,65 @@ internal abstract class IconDecoderCore : IImageDecoderInternals
             // Decode the frame into a temp image buffer. This is disposed after the frame is copied to the result.
             ImageInfo temp = this.GetDecoder(isPng).Identify(stream, cancellationToken);
 
-            frames[i] = new();
-            if (!isPng)
+            ImageFrameMetadata frameMetadata = new();
+
+            if (isPng)
+            {
+                if (i == 0)
+                {
+                    pngMetadata = temp.Metadata.GetPngMetadata();
+                }
+
+                frameMetadata.SetFormatMetadata(PngFormat.Instance, temp.FrameMetadataCollection[0].GetPngMetadata());
+            }
+            else
             {
-                bitsPerPixel = temp.Metadata.GetBmpMetadata().BitsPerPixel;
+                BmpMetadata meta = temp.Metadata.GetBmpMetadata();
+                bitsPerPixel = meta.BitsPerPixel;
+                colorTable = meta.ColorTable;
+
+                if (i == 0)
+                {
+                    bmpMetadata = meta;
+                }
             }
 
             bpp = Math.Max(bpp, (int)bitsPerPixel);
 
-            this.SetFrameMetadata(frames[i], this.entries[i], isPng ? IconFrameCompression.Png : IconFrameCompression.Bmp, bitsPerPixel);
+            frames[i] = frameMetadata;
+
+            this.SetFrameMetadata(
+                frames[i],
+                this.entries[i],
+                isPng ? IconFrameCompression.Png : IconFrameCompression.Bmp,
+                bitsPerPixel,
+                colorTable);
 
             // Since Windows Vista, the size of an image is determined from the BITMAPINFOHEADER structure or PNG image data
             // which technically allows storing icons with larger than 256 pixels, but such larger sizes are not recommended by Microsoft.
             this.Dimensions = new(Math.Max(this.Dimensions.Width, temp.Size.Width), Math.Max(this.Dimensions.Height, temp.Size.Height));
         }
 
+        // Copy the format specific metadata to the image.
+        if (bmpMetadata != null)
+        {
+            metadata.SetFormatMetadata(BmpFormat.Instance, bmpMetadata);
+        }
+
+        if (pngMetadata != null)
+        {
+            metadata.SetFormatMetadata(PngFormat.Instance, pngMetadata);
+        }
+
         return new(new(bpp), this.Dimensions, metadata, frames);
     }
 
-    protected abstract void SetFrameMetadata(ImageFrameMetadata metadata, in IconDirEntry entry, IconFrameCompression compression, BmpBitsPerPixel bitsPerPixel);
+    protected abstract void SetFrameMetadata(
+        ImageFrameMetadata metadata,
+        in IconDirEntry entry,
+        IconFrameCompression compression,
+        BmpBitsPerPixel bitsPerPixel,
+        ReadOnlyMemory<Color>? colorTable);
 
     [MemberNotNull(nameof(entries))]
     protected void ReadHeader(Stream stream)
diff --git a/src/ImageSharp/Formats/Icon/IconEncoderCore.cs b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
index eb07ab483..243339661 100644
--- a/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
+++ b/src/ImageSharp/Formats/Icon/IconEncoderCore.cs
@@ -13,12 +13,16 @@ namespace SixLabors.ImageSharp.Formats.Icon;
 
 internal abstract class IconEncoderCore : IImageEncoderInternals
 {
+    private readonly QuantizingImageEncoder encoder;
     private readonly IconFileType iconFileType;
     private IconDir fileHeader;
     private EncodingFrameMetadata[]? entries;
 
-    protected IconEncoderCore(IconFileType iconFileType)
-        => this.iconFileType = iconFileType;
+    protected IconEncoderCore(QuantizingImageEncoder encoder, IconFileType iconFileType)
+    {
+        this.encoder = encoder;
+        this.iconFileType = iconFileType;
+    }
 
     public void Encode<TPixel>(
         Image<TPixel> image,
@@ -71,14 +75,7 @@ internal abstract class IconEncoderCore : IImageEncoderInternals
             {
                 IconFrameCompression.Bmp => new BmpEncoder()
                 {
-                    // We don't have access to the palette in the metadata so we need to quantize the image
-                    // using a new one generated from the pixel data.
-                    Quantizer = encodingMetadata.Entry.BitCount <= 8
-                    ? new WuQuantizer(new()
-                    {
-                        MaxColors = encodingMetadata.Entry.ColorCount
-                    })
-                    : null,
+                    Quantizer = this.GetQuantizer(encodingMetadata),
                     ProcessedAlphaMask = true,
                     UseDoubleHeight = true,
                     SkipFileHeader = true,
@@ -122,28 +119,65 @@ internal abstract class IconEncoderCore : IImageEncoderInternals
             image.Frames.Select(i =>
             {
                 IcoFrameMetadata metadata = i.Metadata.GetIcoMetadata();
-                return new EncodingFrameMetadata(metadata.Compression, metadata.BmpBitsPerPixel, metadata.ToIconDirEntry());
+                return new EncodingFrameMetadata(metadata.Compression, metadata.BmpBitsPerPixel, metadata.ColorTable, metadata.ToIconDirEntry());
             }).ToArray(),
             IconFileType.CUR =>
             image.Frames.Select(i =>
             {
                 CurFrameMetadata metadata = i.Metadata.GetCurMetadata();
-                return new EncodingFrameMetadata(metadata.Compression, metadata.BmpBitsPerPixel, metadata.ToIconDirEntry());
+                return new EncodingFrameMetadata(metadata.Compression, metadata.BmpBitsPerPixel, metadata.ColorTable, metadata.ToIconDirEntry());
             }).ToArray(),
             _ => throw new NotSupportedException(),
         };
     }
 
-    internal sealed class EncodingFrameMetadata(
-        IconFrameCompression compression,
-        BmpBitsPerPixel bmpBitsPerPixel,
-        IconDirEntry iconDirEntry)
+    private IQuantizer? GetQuantizer(EncodingFrameMetadata metadata)
     {
-        private IconDirEntry iconDirEntry = iconDirEntry;
+        if (metadata.Entry.BitCount > 8)
+        {
+            return null;
+        }
+
+        if (this.encoder.Quantizer is not null)
+        {
+            return this.encoder.Quantizer;
+        }
+
+        if (metadata.ColorTable is null)
+        {
+            return new WuQuantizer(new()
+            {
+                MaxColors = metadata.Entry.ColorCount
+            });
+        }
+
+        // Don't dither if we have a palette. We want to preserve as much information as possible.
+        return new PaletteQuantizer(metadata.ColorTable.Value, new() { Dither = null });
+    }
+
+    internal sealed class EncodingFrameMetadata
+    {
+        private IconDirEntry iconDirEntry;
+
+        public EncodingFrameMetadata(
+            IconFrameCompression compression,
+            BmpBitsPerPixel bmpBitsPerPixel,
+            ReadOnlyMemory<Color>? colorTable,
+            IconDirEntry iconDirEntry)
+        {
+            this.Compression = compression;
+            this.BmpBitsPerPixel = compression == IconFrameCompression.Png
+                ? BmpBitsPerPixel.Pixel32
+                : bmpBitsPerPixel;
+            this.ColorTable = colorTable;
+            this.iconDirEntry = iconDirEntry;
+        }
+
+        public IconFrameCompression Compression { get; }
 
-        public IconFrameCompression Compression { get; set; } = compression;
+        public BmpBitsPerPixel BmpBitsPerPixel { get; }
 
-        public BmpBitsPerPixel BmpBitsPerPixel { get; set; } = bmpBitsPerPixel;
+        public ReadOnlyMemory<Color>? ColorTable { get; set; }
 
         public ref IconDirEntry Entry => ref this.iconDirEntry;
     }
diff --git a/src/ImageSharp/Formats/Png/PngDecoderCore.cs b/src/ImageSharp/Formats/Png/PngDecoderCore.cs
index 36a0a8bcb..3e278be14 100644
--- a/src/ImageSharp/Formats/Png/PngDecoderCore.cs
+++ b/src/ImageSharp/Formats/Png/PngDecoderCore.cs
@@ -345,9 +345,10 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
     {
         uint frameCount = 0;
         ImageMetadata metadata = new();
+        List<ImageFrameMetadata> framesMetadata = [];
         PngMetadata pngMetadata = metadata.GetPngMetadata();
         this.currentStream = stream;
-        FrameControl? lastFrameControl = null;
+        FrameControl? currentFrameControl = null;
         Span<byte> buffer = stackalloc byte[20];
 
         this.currentStream.Skip(8);
@@ -400,7 +401,8 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
                                 break;
                             }
 
-                            lastFrameControl = this.ReadFrameControlChunk(chunk.Data.GetSpan());
+                            currentFrameControl = this.ReadFrameControlChunk(chunk.Data.GetSpan());
+
                             break;
                         case PngChunkType.FrameData:
                             if (frameCount == this.maxFrames)
@@ -413,22 +415,35 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
                                 goto EOF;
                             }
 
-                            if (lastFrameControl is null)
+                            if (currentFrameControl is null)
                             {
                                 PngThrowHelper.ThrowMissingFrameControl();
                             }
 
+                            InitializeFrameMetadata(framesMetadata, currentFrameControl.Value);
+
                             // Skip sequence number
                             this.currentStream.Skip(4);
                             this.SkipChunkDataAndCrc(chunk);
                             break;
                         case PngChunkType.Data:
+
                             // Spec says tRNS must be before IDAT so safe to exit.
                             if (this.colorMetadataOnly)
                             {
                                 goto EOF;
                             }
 
+                            pngMetadata.AnimateRootFrame = currentFrameControl != null;
+                            currentFrameControl ??= new((uint)this.header.Width, (uint)this.header.Height);
+                            if (framesMetadata.Count == 0)
+                            {
+                                InitializeFrameMetadata(framesMetadata, currentFrameControl.Value);
+
+                                // Both PLTE and tRNS chunks, if present, have been read at this point as per spec.
+                                AssignColorPalette(this.palette, this.paletteAlpha, pngMetadata);
+                            }
+
                             this.SkipChunkDataAndCrc(chunk);
                             break;
                         case PngChunkType.Palette:
@@ -515,7 +530,7 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
             // Both PLTE and tRNS chunks, if present, have been read at this point as per spec.
             AssignColorPalette(this.palette, this.paletteAlpha, pngMetadata);
 
-            return new ImageInfo(new PixelTypeInfo(this.CalculateBitsPerPixel()), new(this.header.Width, this.header.Height), metadata);
+            return new ImageInfo(new PixelTypeInfo(this.CalculateBitsPerPixel()), new(this.header.Width, this.header.Height), metadata, framesMetadata);
         }
         finally
         {
@@ -680,6 +695,14 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
         this.scanline = this.configuration.MemoryAllocator.Allocate<byte>(this.bytesPerScanline, AllocationOptions.Clean);
     }
 
+    private static void InitializeFrameMetadata(List<ImageFrameMetadata> imageFrameMetadata, FrameControl currentFrameControl)
+    {
+        ImageFrameMetadata meta = new();
+        PngFrameMetadata frameMetadata = meta.GetPngMetadata();
+        frameMetadata.FromChunk(currentFrameControl);
+        imageFrameMetadata.Add(meta);
+    }
+
     /// <summary>
     /// Calculates the correct number of bits per pixel for the given color type.
     /// </summary>
diff --git a/src/ImageSharp/Processing/Processors/Quantization/PaletteQuantizer.cs b/src/ImageSharp/Processing/Processors/Quantization/PaletteQuantizer.cs
index acd179ffc..13a59a26d 100644
--- a/src/ImageSharp/Processing/Processors/Quantization/PaletteQuantizer.cs
+++ b/src/ImageSharp/Processing/Processors/Quantization/PaletteQuantizer.cs
@@ -62,9 +62,10 @@ public class PaletteQuantizer : IQuantizer
     {
         Guard.NotNull(options, nameof(options));
 
-        // Always use the palette length over options since the palette cannot be reduced.
-        TPixel[] palette = new TPixel[this.colorPalette.Length];
-        Color.ToPixel(this.colorPalette.Span, palette.AsSpan());
+        // If the palette is larger than the max colors then we need to trim it down.
+        // treat the buffer as FILO.
+        TPixel[] palette = new TPixel[Math.Min(options.MaxColors, this.colorPalette.Length)];
+        Color.ToPixel(this.colorPalette.Span[..palette.Length], palette.AsSpan());
         return new PaletteQuantizer<TPixel>(configuration, options, palette, this.transparentIndex);
     }
 }
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
index e6efda4b6..4efd33648 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurDecoderTests.cs
@@ -1,7 +1,9 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Cur;
+using SixLabors.ImageSharp.Formats.Icon;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Cur;
 
@@ -17,9 +19,11 @@ public class CurDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(CurDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
-
-        // TODO: Assert metadata, frame count, etc
+        CurFrameMetadata meta = image.Frames[0].Metadata.GetCurMetadata();
+        Assert.Equal(image.Width, meta.EncodingWidth);
+        Assert.Equal(image.Height, meta.EncodingHeight);
+        Assert.Equal(IconFrameCompression.Bmp, meta.Compression);
+        Assert.Equal(BmpBitsPerPixel.Pixel32, meta.BmpBitsPerPixel);
     }
 
     [Theory]
@@ -28,9 +32,10 @@ public class CurDecoderTests
     public void CurDecoder_Decode2(TestImageProvider<Rgba32> provider)
     {
         using Image<Rgba32> image = provider.GetImage(CurDecoder.Instance);
-
-        image.DebugSaveMultiFrame(provider, extension: "png");
-
-        // TODO: Assert metadata, frame count, etc
+        CurFrameMetadata meta = image.Frames[0].Metadata.GetCurMetadata();
+        Assert.Equal(image.Width, meta.EncodingWidth);
+        Assert.Equal(image.Height, meta.EncodingHeight);
+        Assert.Equal(IconFrameCompression.Bmp, meta.Compression);
+        Assert.Equal(BmpBitsPerPixel.Pixel32, meta.BmpBitsPerPixel);
     }
 }
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
index 9908786f1..b9b66296d 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Cur/CurEncoderTests.cs
@@ -3,6 +3,7 @@
 
 using SixLabors.ImageSharp.Formats.Cur;
 using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
 using static SixLabors.ImageSharp.Tests.TestImages.Cur;
 
 namespace SixLabors.ImageSharp.Tests.Formats.Icon.Cur;
@@ -10,23 +11,24 @@ namespace SixLabors.ImageSharp.Tests.Formats.Icon.Cur;
 [Trait("Format", "Cur")]
 public class CurEncoderTests
 {
-    private static CurEncoder CurEncoder => new();
-
-    public static readonly TheoryData<string> Files = new()
-    {
-        { WindowsMouse },
-    };
+    private static CurEncoder Encoder => new();
 
     [Theory]
-    [MemberData(nameof(Files))]
-    public void Encode(string imagePath)
+    [WithFile(CurReal, PixelTypes.Rgba32)]
+    [WithFile(WindowsMouse, PixelTypes.Rgba32)]
+    public void CanRoundTripEncoder<TPixel>(TestImageProvider<TPixel> provider)
+    where TPixel : unmanaged, IPixel<TPixel>
     {
-        TestFile testFile = TestFile.Create(imagePath);
-        using Image<Rgba32> input = testFile.CreateRgba32Image();
+        using Image<TPixel> image = provider.GetImage(CurDecoder.Instance);
         using MemoryStream memStream = new();
-        input.Save(memStream, CurEncoder);
+        image.DebugSaveMultiFrame(provider);
 
+        image.Save(memStream, Encoder);
         memStream.Seek(0, SeekOrigin.Begin);
-        CurDecoder.Instance.Decode(new(), memStream);
+
+        using Image<TPixel> encoded = Image.Load<TPixel>(memStream);
+        encoded.DebugSaveMultiFrame(provider, appendPixelTypeToFileName: false);
+
+        encoded.CompareToOriginalMultiFrame(provider, ImageComparer.Exact, CurDecoder.Instance);
     }
 }
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
index 1c724ca35..a776a637b 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoDecoderTests.cs
@@ -1,7 +1,9 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Ico;
+using SixLabors.ImageSharp.Formats.Icon;
 using SixLabors.ImageSharp.PixelFormats;
 using static SixLabors.ImageSharp.Tests.TestImages.Ico;
 
@@ -17,9 +19,9 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        image.DebugSaveMultiFrame(provider);
 
-        // TODO: Assert metadata, frame count, etc
+        Assert.Equal(10, image.Frames.Count);
     }
 
     [Theory]
@@ -45,9 +47,16 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        image.DebugSave(provider);
 
-        // TODO: Assert metadata, frame count, etc
+        IcoFrameMetadata meta = image.Frames.RootFrame.Metadata.GetIcoMetadata();
+        int expectedWidth = image.Width >= 256 ? 0 : image.Width;
+        int expectedHeight = image.Height >= 256 ? 0 : image.Height;
+
+        Assert.Equal(expectedWidth, meta.EncodingWidth);
+        Assert.Equal(expectedHeight, meta.EncodingHeight);
+        Assert.Equal(IconFrameCompression.Bmp, meta.Compression);
+        Assert.Equal(BmpBitsPerPixel.Pixel1, meta.BmpBitsPerPixel);
     }
 
     [Theory]
@@ -74,9 +83,16 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        image.DebugSave(provider);
+
+        IcoFrameMetadata meta = image.Frames.RootFrame.Metadata.GetIcoMetadata();
+        int expectedWidth = image.Width >= 256 ? 0 : image.Width;
+        int expectedHeight = image.Height >= 256 ? 0 : image.Height;
 
-        // TODO: Assert metadata, frame count, etc
+        Assert.Equal(expectedWidth, meta.EncodingWidth);
+        Assert.Equal(expectedHeight, meta.EncodingHeight);
+        Assert.Equal(IconFrameCompression.Bmp, meta.Compression);
+        Assert.Equal(BmpBitsPerPixel.Pixel24, meta.BmpBitsPerPixel);
     }
 
     [Theory]
@@ -103,9 +119,16 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        image.DebugSave(provider);
 
-        // TODO: Assert metadata, frame count, etc
+        IcoFrameMetadata meta = image.Frames.RootFrame.Metadata.GetIcoMetadata();
+        int expectedWidth = image.Width >= 256 ? 0 : image.Width;
+        int expectedHeight = image.Height >= 256 ? 0 : image.Height;
+
+        Assert.Equal(expectedWidth, meta.EncodingWidth);
+        Assert.Equal(expectedHeight, meta.EncodingHeight);
+        Assert.Equal(IconFrameCompression.Bmp, meta.Compression);
+        Assert.Equal(BmpBitsPerPixel.Pixel32, meta.BmpBitsPerPixel);
     }
 
     [Theory]
@@ -131,9 +154,16 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        image.DebugSave(provider);
+
+        IcoFrameMetadata meta = image.Frames.RootFrame.Metadata.GetIcoMetadata();
+        int expectedWidth = image.Width >= 256 ? 0 : image.Width;
+        int expectedHeight = image.Height >= 256 ? 0 : image.Height;
 
-        // TODO: Assert metadata, frame count, etc
+        Assert.Equal(expectedWidth, meta.EncodingWidth);
+        Assert.Equal(expectedHeight, meta.EncodingHeight);
+        Assert.Equal(IconFrameCompression.Bmp, meta.Compression);
+        Assert.Equal(BmpBitsPerPixel.Pixel4, meta.BmpBitsPerPixel);
     }
 
     [Theory]
@@ -151,7 +181,8 @@ public class IcoDecoderTests
     [WithFile(Bpp8Size5x5, PixelTypes.Rgba32)]
     [WithFile(Bpp8Size6x6, PixelTypes.Rgba32)]
     [WithFile(Bpp8Size7x7, PixelTypes.Rgba32)]
-    [WithFile(Bpp8Size8x8, PixelTypes.Rgba32)]
+
+    // [WithFile(Bpp8Size8x8, PixelTypes.Rgba32)] This is actually 24 bit.
     [WithFile(Bpp8Size9x9, PixelTypes.Rgba32)]
     [WithFile(Bpp8TranspNotSquare, PixelTypes.Rgba32)]
     [WithFile(Bpp8TranspPartial, PixelTypes.Rgba32)]
@@ -159,9 +190,16 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        image.DebugSave(provider);
+
+        IcoFrameMetadata meta = image.Frames.RootFrame.Metadata.GetIcoMetadata();
+        int expectedWidth = image.Width >= 256 ? 0 : image.Width;
+        int expectedHeight = image.Height >= 256 ? 0 : image.Height;
 
-        // TODO: Assert metadata, frame count, etc
+        Assert.Equal(expectedWidth, meta.EncodingWidth);
+        Assert.Equal(expectedHeight, meta.EncodingHeight);
+        Assert.Equal(IconFrameCompression.Bmp, meta.Compression);
+        Assert.Equal(BmpBitsPerPixel.Pixel8, meta.BmpBitsPerPixel);
     }
 
     [Theory]
@@ -174,10 +212,6 @@ public class IcoDecoderTests
         => Assert.Throws<NotSupportedException>(() =>
         {
             using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
-
-            image.DebugSaveMultiFrame(provider, extension: "png");
-
-            // TODO: Assert metadata, frame count, etc
         });
 
     [Theory]
@@ -186,9 +220,16 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        image.DebugSave(provider);
+
+        IcoFrameMetadata meta = image.Frames.RootFrame.Metadata.GetIcoMetadata();
+        int expectedWidth = image.Width >= 256 ? 0 : image.Width;
+        int expectedHeight = image.Height >= 256 ? 0 : image.Height;
 
-        // TODO: Assert metadata, frame count, etc
+        Assert.Equal(expectedWidth, meta.EncodingWidth);
+        Assert.Equal(expectedHeight, meta.EncodingHeight);
+        Assert.Equal(IconFrameCompression.Png, meta.Compression);
+        Assert.Equal(BmpBitsPerPixel.Pixel32, meta.BmpBitsPerPixel);
     }
 
     [Theory]
@@ -199,9 +240,9 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        Assert.True(image.Frames.Count > 1);
 
-        // TODO: Assert metadata, frame count, etc
+        image.DebugSaveMultiFrame(provider);
     }
 
     [Theory]
@@ -215,9 +256,46 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        Assert.True(image.Frames.Count > 1);
+
+        for (int i = 0; i < image.Frames.Count; i++)
+        {
+            ImageFrame<Rgba32> frame = image.Frames[i];
+            IcoFrameMetadata meta = frame.Metadata.GetIcoMetadata();
+            Assert.Equal(BmpBitsPerPixel.Pixel32, meta.BmpBitsPerPixel);
+        }
+
+        image.DebugSaveMultiFrame(provider);
+    }
+
+    [Theory]
+    [WithFile(MultiSizeA, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeB, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeC, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeD, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeE, PixelTypes.Rgba32)]
+    [WithFile(MultiSizeF, PixelTypes.Rgba32)]
+    public void MultiSize_CanDecodeSingleFrame(TestImageProvider<Rgba32> provider)
+    {
+        using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance, new() { MaxFrames = 1 });
+        Assert.Single(image.Frames);
+    }
 
-        // TODO: Assert metadata, frame count, etc
+    [Theory]
+    [InlineData(MultiSizeA)]
+    [InlineData(MultiSizeB)]
+    [InlineData(MultiSizeC)]
+    [InlineData(MultiSizeD)]
+    [InlineData(MultiSizeE)]
+    [InlineData(MultiSizeF)]
+    public void MultiSize_CanIdentifySingleFrame(string imagePath)
+    {
+        TestFile testFile = TestFile.Create(imagePath);
+        using MemoryStream stream = new(testFile.Bytes, false);
+
+        ImageInfo imageInfo = Image.Identify(new() { MaxFrames = 1 }, stream);
+
+        Assert.Single(imageInfo.FrameMetadataCollection);
     }
 
     [Theory]
@@ -229,9 +307,9 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        Assert.True(image.Frames.Count > 1);
 
-        // TODO: Assert metadata, frame count, etc
+        image.DebugSaveMultiFrame(provider);
     }
 
     [Theory]
@@ -240,8 +318,15 @@ public class IcoDecoderTests
     {
         using Image<Rgba32> image = provider.GetImage(IcoDecoder.Instance);
 
-        image.DebugSaveMultiFrame(provider, extension: "png");
+        image.DebugSave(provider);
+
+        IcoFrameMetadata meta = image.Frames.RootFrame.Metadata.GetIcoMetadata();
+        int expectedWidth = image.Width >= 256 ? 0 : image.Width;
+        int expectedHeight = image.Height >= 256 ? 0 : image.Height;
 
-        // TODO: Assert metadata, frame count, etc
+        Assert.Equal(expectedWidth, meta.EncodingWidth);
+        Assert.Equal(expectedHeight, meta.EncodingHeight);
+        Assert.Equal(IconFrameCompression.Bmp, meta.Compression);
+        Assert.Equal(BmpBitsPerPixel.Pixel32, meta.BmpBitsPerPixel);
     }
 }
diff --git a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoEncoderTests.cs
index 9a239bdd4..db28f9f70 100644
--- a/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Icon/Ico/IcoEncoderTests.cs
@@ -3,6 +3,7 @@
 
 using SixLabors.ImageSharp.Formats.Ico;
 using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
 using static SixLabors.ImageSharp.Tests.TestImages.Ico;
 
 namespace SixLabors.ImageSharp.Tests.Formats.Icon.Ico;
@@ -10,23 +11,24 @@ namespace SixLabors.ImageSharp.Tests.Formats.Icon.Ico;
 [Trait("Format", "Icon")]
 public class IcoEncoderTests
 {
-    private static IcoEncoder CurEncoder => new();
-
-    public static readonly TheoryData<string> Files = new()
-    {
-        { Flutter },
-    };
+    private static IcoEncoder Encoder => new();
 
     [Theory]
-    [MemberData(nameof(Files))]
-    public void Encode(string imagePath)
+    [WithFile(Flutter, PixelTypes.Rgba32)]
+    public void CanRoundTripEncoder<TPixel>(TestImageProvider<TPixel> provider)
+        where TPixel : unmanaged, IPixel<TPixel>
     {
-        TestFile testFile = TestFile.Create(imagePath);
-        using Image<Rgba32> input = testFile.CreateRgba32Image();
+        using Image<TPixel> image = provider.GetImage(IcoDecoder.Instance);
         using MemoryStream memStream = new();
-        input.Save(memStream, CurEncoder);
+        image.DebugSaveMultiFrame(provider);
 
+        image.Save(memStream, Encoder);
         memStream.Seek(0, SeekOrigin.Begin);
-        IcoDecoder.Instance.Decode(new(), memStream);
+
+        using Image<TPixel> encoded = Image.Load<TPixel>(memStream);
+        encoded.DebugSaveMultiFrame(provider, appendPixelTypeToFileName: false);
+
+        // Despite preservation of the palette. The process can still be lossy
+        encoded.CompareToOriginalMultiFrame(provider, ImageComparer.TolerantPercentage(.23f), IcoDecoder.Instance);
     }
 }