Add support for decoding 24bit per channel color tiff with contiguous pixel data

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero16TiffColor{TPixel}.cs

@@ -39,7 +39,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 {
                     for (int x = 0; x < pixelRow.Length; x++)
                     {
-                        ushort intensity = TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2));
+                        ushort intensity = TiffUtils.ConvertToUShortBigEndian(data.Slice(offset, 2));
                         offset += 2;
 
                         pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
@@ -49,7 +49,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 {
                     for (int x = 0; x < pixelRow.Length; x++)
                     {
-                        ushort intensity = TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2));
+                        ushort intensity = TiffUtils.ConvertToUShortLittleEndian(data.Slice(offset, 2));
                         offset += 2;
 
                         pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/Rgb161616TiffColor{TPixel}.cs

@@ -41,11 +41,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 {
                     for (int x = 0; x < pixelRow.Length; x++)
                     {
-                        ulong r = TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2));
+                        ulong r = TiffUtils.ConvertToUShortBigEndian(data.Slice(offset, 2));
                         offset += 2;
-                        ulong g = TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2));
+                        ulong g = TiffUtils.ConvertToUShortBigEndian(data.Slice(offset, 2));
                         offset += 2;
-                        ulong b = TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2));
+                        ulong b = TiffUtils.ConvertToUShortBigEndian(data.Slice(offset, 2));
                         offset += 2;
 
                         pixelRow[x] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);
@@ -55,11 +55,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 {
                     for (int x = 0; x < pixelRow.Length; x++)
                     {
-                        ulong r = TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2));
+                        ulong r = TiffUtils.ConvertToUShortLittleEndian(data.Slice(offset, 2));
                         offset += 2;
-                        ulong g = TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2));
+                        ulong g = TiffUtils.ConvertToUShortLittleEndian(data.Slice(offset, 2));
                         offset += 2;
-                        ulong b = TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2));
+                        ulong b = TiffUtils.ConvertToUShortLittleEndian(data.Slice(offset, 2));
                         offset += 2;
 
                         pixelRow[x] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/Rgb16PlanarTiffColor{TPixel}.cs

@@ -44,9 +44,9 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 {
                     for (int x = 0; x < pixelRow.Length; x++)
                     {
-                        ulong r = TiffUtils.ConvertToShortBigEndian(redData.Slice(offset, 2));
-                        ulong g = TiffUtils.ConvertToShortBigEndian(greenData.Slice(offset, 2));
-                        ulong b = TiffUtils.ConvertToShortBigEndian(blueData.Slice(offset, 2));
+                        ulong r = TiffUtils.ConvertToUShortBigEndian(redData.Slice(offset, 2));
+                        ulong g = TiffUtils.ConvertToUShortBigEndian(greenData.Slice(offset, 2));
+                        ulong b = TiffUtils.ConvertToUShortBigEndian(blueData.Slice(offset, 2));
 
                         offset += 2;
 
@@ -57,9 +57,9 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 {
                     for (int x = 0; x < pixelRow.Length; x++)
                     {
-                        ulong r = TiffUtils.ConvertToShortLittleEndian(redData.Slice(offset, 2));
-                        ulong g = TiffUtils.ConvertToShortLittleEndian(greenData.Slice(offset, 2));
-                        ulong b = TiffUtils.ConvertToShortLittleEndian(blueData.Slice(offset, 2));
+                        ulong r = TiffUtils.ConvertToUShortLittleEndian(redData.Slice(offset, 2));
+                        ulong g = TiffUtils.ConvertToUShortLittleEndian(greenData.Slice(offset, 2));
+                        ulong b = TiffUtils.ConvertToUShortLittleEndian(blueData.Slice(offset, 2));
 
                         offset += 2;
 

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/Rgb242424TiffColor{TPixel}.cs

@@ -0,0 +1,89 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Numerics;
+using SixLabors.ImageSharp.Formats.Tiff.Utils;
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
+{
+    /// <summary>
+    /// Implements the 'RGB' photometric interpretation with 16 bits for each channel.
+    /// </summary>
+    internal class Rgb242424TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        private readonly bool isBigEndian;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Rgb242424TiffColor{TPixel}" /> class.
+        /// </summary>
+        /// <param name="isBigEndian">if set to <c>true</c> decodes the pixel data as big endian, otherwise as little endian.</param>
+        public Rgb242424TiffColor(bool isBigEndian) => this.isBigEndian = isBigEndian;
+
+        /// <inheritdoc/>
+        public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        {
+            // Note: due to an issue with netcore 2.1 and default values and unpredictable behavior with those,
+            // we define our own defaults as a workaround. See: https://github.com/dotnet/runtime/issues/55623
+            var color = default(TPixel);
+            color.FromVector4(TiffUtils.Vector4Default);
+            int offset = 0;
+            float scale = 1.0f / 0xFFFFFF;
+            byte[] buffer = new byte[4];
+            int bufferStartIdx = this.isBigEndian ? 1 : 0;
+
+            for (int y = top; y < top + height; y++)
+            {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+
+                if (this.isBigEndian)
+                {
+                    for (int x = 0; x < pixelRow.Length; x++)
+                    {
+                        data.Slice(offset, 3).CopyTo(buffer.AsSpan(bufferStartIdx));
+                        ulong r = TiffUtils.ConvertToUIntBigEndian(buffer);
+                        offset += 3;
+
+                        data.Slice(offset, 3).CopyTo(buffer.AsSpan(bufferStartIdx));
+                        ulong g = TiffUtils.ConvertToUIntBigEndian(buffer);
+                        offset += 3;
+
+                        data.Slice(offset, 3).CopyTo(buffer.AsSpan(bufferStartIdx));
+                        ulong b = TiffUtils.ConvertToUIntBigEndian(buffer);
+                        offset += 3;
+
+                        var colorVector = new Vector4(r * scale, g * scale, b * scale, 1.0f);
+                        color.FromVector4(colorVector);
+
+                        pixelRow[x] = color;
+                    }
+                }
+                else
+                {
+                    for (int x = 0; x < pixelRow.Length; x++)
+                    {
+                        data.Slice(offset, 3).CopyTo(buffer.AsSpan(bufferStartIdx));
+                        ulong r = TiffUtils.ConvertToUIntLittleEndian(buffer);
+                        offset += 3;
+
+                        data.Slice(offset, 3).CopyTo(buffer.AsSpan(bufferStartIdx));
+                        ulong g = TiffUtils.ConvertToUIntLittleEndian(buffer);
+                        offset += 3;
+
+                        data.Slice(offset, 3).CopyTo(buffer.AsSpan(bufferStartIdx));
+                        ulong b = TiffUtils.ConvertToUIntLittleEndian(buffer);
+                        offset += 3;
+
+                        var colorVector = new Vector4(r * scale, g * scale, b * scale, 1.0f);
+                        color.FromVector4(colorVector);
+
+                        pixelRow[x] = color;
+                    }
+                }
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/TiffColorDecoderFactory{TPixel}.cs

@@ -136,6 +136,16 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                     DebugGuard.IsTrue(colorMap == null, "colorMap");
                     return new Rgb161616TiffColor<TPixel>(isBigEndian: byteOrder == ByteOrder.BigEndian);
 
+                case TiffColorType.Rgb242424:
+                    DebugGuard.IsTrue(
+                        bitsPerSample.Channels == 3
+                        && bitsPerSample.Channel2 == 24
+                        && bitsPerSample.Channel1 == 24
+                        && bitsPerSample.Channel0 == 24,
+                        "bitsPerSample");
+                    DebugGuard.IsTrue(colorMap == null, "colorMap");
+                    return new Rgb242424TiffColor<TPixel>(isBigEndian: byteOrder == ByteOrder.BigEndian);
+
                 case TiffColorType.PaletteColor:
                     DebugGuard.NotNull(colorMap, "colorMap");
                     return new PaletteTiffColor<TPixel>(bitsPerSample, colorMap);

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/TiffColorType.cs

@@ -103,6 +103,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
         /// </summary>
         Rgb161616,
 
+        /// <summary>
+        /// RGB color image with 24 bits for each channel.
+        /// </summary>
+        Rgb242424,
+
         /// <summary>
         /// RGB Full Color. Planar configuration of data.
         /// </summary>

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero16TiffColor{TPixel}.cs

@@ -39,7 +39,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 {
                     for (int x = 0; x < pixelRow.Length; x++)
                     {
-                        ushort intensity = (ushort)(ushort.MaxValue - TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2)));
+                        ushort intensity = (ushort)(ushort.MaxValue - TiffUtils.ConvertToUShortBigEndian(data.Slice(offset, 2)));
                         offset += 2;
 
                         pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
@@ -49,7 +49,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 {
                     for (int x = 0; x < pixelRow.Length; x++)
                     {
-                        ushort intensity = (ushort)(ushort.MaxValue - TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2)));
+                        ushort intensity = (ushort)(ushort.MaxValue - TiffUtils.ConvertToUShortLittleEndian(data.Slice(offset, 2)));
                         offset += 2;
 
                         pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);

src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs

@@ -206,6 +206,10 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                         ushort bitsPerChannel = options.BitsPerSample.Channel0;
                         switch (bitsPerChannel)
                         {
+                            case 24:
+                                options.ColorType = TiffColorType.Rgb242424;
+                                break;
+
                             case 16:
                                 options.ColorType = TiffColorType.Rgb161616;
                                 break;

src/ImageSharp/Formats/Tiff/Utils/TiffUtils.cs

@@ -21,12 +21,16 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Utils
         public static L16 L16Default { get; } = new L16(0);
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ushort ConvertToShortBigEndian(ReadOnlySpan<byte> buffer) =>
-            BinaryPrimitives.ReadUInt16BigEndian(buffer);
+        public static ushort ConvertToUShortBigEndian(ReadOnlySpan<byte> buffer) => BinaryPrimitives.ReadUInt16BigEndian(buffer);
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ushort ConvertToShortLittleEndian(ReadOnlySpan<byte> buffer) =>
-            BinaryPrimitives.ReadUInt16LittleEndian(buffer);
+        public static ushort ConvertToUShortLittleEndian(ReadOnlySpan<byte> buffer) => BinaryPrimitives.ReadUInt16LittleEndian(buffer);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static uint ConvertToUIntBigEndian(ReadOnlySpan<byte> buffer) => BinaryPrimitives.ReadUInt32BigEndian(buffer);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static uint ConvertToUIntLittleEndian(ReadOnlySpan<byte> buffer) => BinaryPrimitives.ReadUInt32LittleEndian(buffer);
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static TPixel ColorFromL8<TPixel>(L8 l8, byte intensity, TPixel color)

tests/ImageSharp.Tests/Formats/Tiff/TiffDecoderTests.cs

@@ -173,6 +173,12 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
         public void TiffDecoder_CanDecode_48Bit<TPixel>(TestImageProvider<TPixel> provider)
             where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider);
 
+        [Theory]
+        [WithFile(FlowerRgb242424Contiguous, PixelTypes.Rgba32)]
+        [WithFile(FlowerRgb242424ContiguousLittleEndian, PixelTypes.Rgba32)]
+        public void TiffDecoder_CanDecode_72Bit<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider);
+
         [Theory]
         [WithFile(GrayscaleDeflateMultistrip, PixelTypes.Rgba32)]
         [WithFile(RgbDeflateMultistrip, PixelTypes.Rgba32)]

tests/ImageSharp.Tests/TestImages.cs

@@ -561,6 +561,8 @@ namespace SixLabors.ImageSharp.Tests
             public const string RgbPalette = "Tiff/rgb_palette.tiff";
             public const string Rgb4BitPalette = "Tiff/bike_colorpalette_4bit.tiff";
             public const string RgbPaletteDeflate = "Tiff/rgb_palette_deflate.tiff";
+            public const string FlowerRgb242424Contiguous = "Tiff/flower-rgb-contig-24.tiff";
+            public const string FlowerRgb242424ContiguousLittleEndian = "Tiff/flower-rgb-contig-24_lsb.tiff";
             public const string FlowerRgb161616Contiguous = "Tiff/flower-rgb-contig-16.tiff";
             public const string FlowerRgb161616ContiguousLittleEndian = "Tiff/flower-rgb-contig-16_lsb.tiff";
             public const string FlowerRgb161616Planar = "Tiff/flower-rgb-planar-16.tiff";

tests/Images/Input/Tiff/flower-rgb-contig-24.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c6368a704b0a629239024f6fbfb30723fa317593ef36ddba05d76302530bd974
+size 28568

tests/Images/Input/Tiff/flower-rgb-contig-24_lsb.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:bbb2b4ca6d7eeee4737c6963c99ef68fb6971cf6ccee463427a8246574bc6440
+size 28632