Merge branch 'master' into js/fix-divide-by-zero

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

@@ -0,0 +1,61 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using SixLabors.ImageSharp.Formats.Tiff.Utils;
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
+{
+    /// <summary>
+    /// Implements the 'BlackIsZero' photometric interpretation for 16-bit grayscale images.
+    /// </summary>
+    internal class BlackIsZero16TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        private readonly bool isBigEndian;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BlackIsZero16TiffColor{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 BlackIsZero16TiffColor(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
+            L16 l16 = TiffUtils.L16Default;
+            var color = default(TPixel);
+            color.FromVector4(TiffUtils.Vector4Default);
+
+            int offset = 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++)
+                    {
+                        ushort intensity = TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2));
+                        offset += 2;
+
+                        pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
+                    }
+                }
+                else
+                {
+                    for (int x = 0; x < pixelRow.Length; x++)
+                    {
+                        ushort intensity = TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2));
+                        offset += 2;
+
+                        pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
+                    }
+                }
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero8TiffColor{TPixel}.cs

@@ -2,7 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-
+using SixLabors.ImageSharp.Formats.Tiff.Utils;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -24,14 +24,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             var l8 = default(L8);
             for (int y = top; y < top + height; y++)
             {
-                for (int x = left; x < left + width; x++)
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+                for (int x = 0; x < pixelRow.Length; x++)
                 {
                     byte intensity = data[offset++];
-
-                    l8.PackedValue = intensity;
-                    color.FromL8(l8);
-
-                    pixels[x, y] = color;
+                    pixelRow[x] = TiffUtils.ColorFromL8(l8, intensity, color);
                 }
             }
         }

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

@@ -34,13 +34,14 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
-                for (int x = left; x < left + width; x++)
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+                for (int x = 0; x < pixelRow.Length; x++)
                 {
                     int value = bitReader.ReadBits(this.bitsPerSample0);
                     float intensity = value / this.factor;
 
                     color.FromVector4(new Vector4(intensity, intensity, intensity, 1.0f));
-                    pixels[x, y] = color;
+                    pixelRow[x] = color;
                 }
 
                 bitReader.NextRow();

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

@@ -35,10 +35,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
-                for (int x = left; x < left + width; x++)
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+                for (int x = 0; x < pixelRow.Length; x++)
                 {
                     int index = bitReader.ReadBits(this.bitsPerSample0);
-                    pixels[x, y] = this.palette[index];
+                    pixelRow[x] = this.palette[index];
                 }
 
                 bitReader.NextRow();

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

@@ -2,7 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-using System.Buffers.Binary;
+using SixLabors.ImageSharp.Formats.Tiff.Utils;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -25,34 +25,47 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
         /// <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
+            Rgba64 rgba = TiffUtils.Rgba64Default;
             var color = default(TPixel);
+            color.FromVector4(TiffUtils.Vector4Default);
 
             int offset = 0;
 
-            var rgba = default(Rgba64);
             for (int y = top; y < top + height; y++)
             {
-                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
 
-                for (int x = left; x < left + width; x++)
+                if (this.isBigEndian)
                 {
-                    ulong r = this.ConvertToShort(data.Slice(offset, 2));
-                    offset += 2;
-                    ulong g = this.ConvertToShort(data.Slice(offset, 2));
-                    offset += 2;
-                    ulong b = this.ConvertToShort(data.Slice(offset, 2));
-                    offset += 2;
+                    for (int x = 0; x < pixelRow.Length; x++)
+                    {
+                        ulong r = TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2));
+                        offset += 2;
+                        ulong g = TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2));
+                        offset += 2;
+                        ulong b = TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2));
+                        offset += 2;
 
-                    rgba.PackedValue = r | (g << 16) | (b << 32) | (0xfffful << 48);
-                    color.FromRgba64(rgba);
+                        pixelRow[x] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);
+                    }
+                }
+                else
+                {
+                    for (int x = 0; x < pixelRow.Length; x++)
+                    {
+                        ulong r = TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2));
+                        offset += 2;
+                        ulong g = TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2));
+                        offset += 2;
+                        ulong b = TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2));
+                        offset += 2;
 
-                    pixelRow[x] = color;
+                        pixelRow[x] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);
+                    }
                 }
             }
         }
-
-        private ushort ConvertToShort(ReadOnlySpan<byte> buffer) => this.isBigEndian
-                ? BinaryPrimitives.ReadUInt16BigEndian(buffer)
-                : BinaryPrimitives.ReadUInt16LittleEndian(buffer);
     }
 }

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

@@ -0,0 +1,72 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Buffers;
+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 'Planar' layout for all 16 bit.
+    /// </summary>
+    internal class Rgb16PlanarTiffColor<TPixel> : TiffBasePlanarColorDecoder<TPixel>
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        private readonly bool isBigEndian;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Rgb16PlanarTiffColor{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 Rgb16PlanarTiffColor(bool isBigEndian) => this.isBigEndian = isBigEndian;
+
+        /// <inheritdoc/>
+        public override void Decode(IMemoryOwner<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
+            Rgba64 rgba = TiffUtils.Rgba64Default;
+            var color = default(TPixel);
+            color.FromVector4(TiffUtils.Vector4Default);
+
+            Span<byte> redData = data[0].GetSpan();
+            Span<byte> greenData = data[1].GetSpan();
+            Span<byte> blueData = data[2].GetSpan();
+
+            int offset = 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++)
+                    {
+                        ulong r = TiffUtils.ConvertToShortBigEndian(redData.Slice(offset, 2));
+                        ulong g = TiffUtils.ConvertToShortBigEndian(greenData.Slice(offset, 2));
+                        ulong b = TiffUtils.ConvertToShortBigEndian(blueData.Slice(offset, 2));
+
+                        offset += 2;
+
+                        pixelRow[x] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);
+                    }
+                }
+                else
+                {
+                    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));
+
+                        offset += 2;
+
+                        pixelRow[x] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);
+                    }
+                }
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/Rgb888TiffColor{TPixel}.cs

@@ -24,9 +24,9 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             var rgba = default(Rgba32);
             for (int y = top; y < top + height; y++)
             {
-                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
 
-                for (int x = left; x < left + width; x++)
+                for (int x = 0; x < pixelRow.Length; x++)
                 {
                     byte r = data[offset++];
                     byte g = data[offset++];

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

@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.Buffers;
 using System.Numerics;
 using SixLabors.ImageSharp.Formats.Tiff.Utils;
@@ -12,7 +13,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
     /// <summary>
     /// Implements the 'RGB' photometric interpretation with 'Planar' layout (for all bit depths).
     /// </summary>
-    internal class RgbPlanarTiffColor<TPixel>
+    internal class RgbPlanarTiffColor<TPixel> : TiffBasePlanarColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private readonly float rFactor;
@@ -47,7 +48,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
         /// <param name="top">The y-coordinate of the  top of the image block.</param>
         /// <param name="width">The width of the image block.</param>
         /// <param name="height">The height of the image block.</param>
-        public void Decode(IMemoryOwner<byte>[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        public override void Decode(IMemoryOwner<byte>[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
         {
             var color = default(TPixel);
 
@@ -57,14 +58,15 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
-                for (int x = left; x < left + width; x++)
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+                for (int x = 0; x < pixelRow.Length; x++)
                 {
                     float r = rBitReader.ReadBits(this.bitsPerSampleR) / this.rFactor;
                     float g = gBitReader.ReadBits(this.bitsPerSampleG) / this.gFactor;
                     float b = bBitReader.ReadBits(this.bitsPerSampleB) / this.bFactor;
 
                     color.FromVector4(new Vector4(r, g, b, 1.0f));
-                    pixels[x, y] = color;
+                    pixelRow[x] = color;
                 }
 
                 rBitReader.NextRow();

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

@@ -47,14 +47,15 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
-                for (int x = left; x < left + width; x++)
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+                for (int x = 0; x < pixelRow.Length; x++)
                 {
                     float r = bitReader.ReadBits(this.bitsPerSampleR) / this.rFactor;
                     float g = bitReader.ReadBits(this.bitsPerSampleG) / this.gFactor;
                     float b = bitReader.ReadBits(this.bitsPerSampleB) / this.bFactor;
 
                     color.FromVector4(new Vector4(r, g, b, 1.0f));
-                    pixels[x, y] = color;
+                    pixelRow[x] = color;
                 }
 
                 bitReader.NextRow();

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

@@ -0,0 +1,28 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System.Buffers;
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
+{
+    /// <summary>
+    /// The base class for planar color decoders.
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format.</typeparam>
+    internal abstract class TiffBasePlanarColorDecoder<TPixel>
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        /// <summary>
+        /// Decodes source raw pixel data using the current photometric interpretation.
+        /// </summary>
+        /// <param name="data">The buffers to read image data from.</param>
+        /// <param name="pixels">The image buffer to write pixels to.</param>
+        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
+        /// <param name="top">The y-coordinate of the  top of the image block.</param>
+        /// <param name="width">The width of the image block.</param>
+        /// <param name="height">The height of the image block.</param>
+        public abstract void Decode(IMemoryOwner<byte>[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height);
+    }
+}

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

@@ -32,6 +32,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                     DebugGuard.IsTrue(colorMap == null, "colorMap");
                     return new WhiteIsZero8TiffColor<TPixel>();
 
+                case TiffColorType.WhiteIsZero16:
+                    DebugGuard.IsTrue(bitsPerSample.Channels == 1 && bitsPerSample.Channel0 == 16, "bitsPerSample");
+                    DebugGuard.IsTrue(colorMap == null, "colorMap");
+                    return new WhiteIsZero16TiffColor<TPixel>(byteOrder == ByteOrder.BigEndian);
+
                 case TiffColorType.BlackIsZero:
                     DebugGuard.IsTrue(bitsPerSample.Channels == 1, "bitsPerSample");
                     DebugGuard.IsTrue(colorMap == null, "colorMap");
@@ -52,6 +57,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                     DebugGuard.IsTrue(colorMap == null, "colorMap");
                     return new BlackIsZero8TiffColor<TPixel>();
 
+                case TiffColorType.BlackIsZero16:
+                    DebugGuard.IsTrue(bitsPerSample.Channels == 1 && bitsPerSample.Channel0 == 16, "bitsPerSample");
+                    DebugGuard.IsTrue(colorMap == null, "colorMap");
+                    return new BlackIsZero16TiffColor<TPixel>(byteOrder == ByteOrder.BigEndian);
+
                 case TiffColorType.Rgb:
                     DebugGuard.IsTrue(colorMap == null, "colorMap");
                     return new RgbTiffColor<TPixel>(bitsPerSample);
@@ -135,12 +145,17 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             }
         }
 
-        public static RgbPlanarTiffColor<TPixel> CreatePlanar(TiffColorType colorType, TiffBitsPerSample bitsPerSample, ushort[] colorMap)
+        public static TiffBasePlanarColorDecoder<TPixel> CreatePlanar(TiffColorType colorType, TiffBitsPerSample bitsPerSample, ushort[] colorMap, ByteOrder byteOrder)
         {
             switch (colorType)
             {
                 case TiffColorType.RgbPlanar:
                     DebugGuard.IsTrue(colorMap == null, "colorMap");
+                    if (bitsPerSample.Channel0 == 16 && bitsPerSample.Channel1 == 16 && bitsPerSample.Channel2 == 16)
+                    {
+                        return new Rgb16PlanarTiffColor<TPixel>(byteOrder == ByteOrder.BigEndian);
+                    }
+
                     return new RgbPlanarTiffColor<TPixel>(bitsPerSample);
 
                 default:

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

@@ -28,6 +28,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
         /// </summary>
         BlackIsZero8,
 
+        /// <summary>
+        /// Grayscale: 0 is imaged as black. The maximum value is imaged as white. Optimized implementation for 16-bit images.
+        /// </summary>
+        BlackIsZero16,
+
         /// <summary>
         /// Grayscale: 0 is imaged as white. The maximum value is imaged as black.
         /// </summary>
@@ -48,6 +53,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
         /// </summary>
         WhiteIsZero8,
 
+        /// <summary>
+        /// Grayscale: 0 is imaged as white. The maximum value is imaged as black. Optimized implementation for 16-bit images.
+        /// </summary>
+        WhiteIsZero16,
+
         /// <summary>
         /// Palette-color.
         /// </summary>

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

@@ -0,0 +1,61 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using SixLabors.ImageSharp.Formats.Tiff.Utils;
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
+{
+    /// <summary>
+    /// Implements the 'WhiteIsZero' photometric interpretation for 16-bit grayscale images.
+    /// </summary>
+    internal class WhiteIsZero16TiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        private readonly bool isBigEndian;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="WhiteIsZero16TiffColor{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 WhiteIsZero16TiffColor(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
+            L16 l16 = TiffUtils.L16Default;
+            var color = default(TPixel);
+            color.FromVector4(TiffUtils.Vector4Default);
+
+            int offset = 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++)
+                    {
+                        ushort intensity = (ushort)(ushort.MaxValue - TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2)));
+                        offset += 2;
+
+                        pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
+                    }
+                }
+                else
+                {
+                    for (int x = 0; x < pixelRow.Length; x++)
+                    {
+                        ushort intensity = (ushort)(ushort.MaxValue - TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2)));
+                        offset += 2;
+
+                        pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
+                    }
+                }
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero8TiffColor{TPixel}.cs

@@ -2,7 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-
+using SixLabors.ImageSharp.Formats.Tiff.Utils;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -24,14 +24,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             var l8 = default(L8);
             for (int y = top; y < top + height; y++)
             {
-                for (int x = left; x < left + width; x++)
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+                for (int x = 0; x < pixelRow.Length; x++)
                 {
                     byte intensity = (byte)(255 - data[offset++]);
-
-                    l8.PackedValue = intensity;
-                    color.FromL8(l8);
-
-                    pixels[x, y] = color;
+                    pixelRow[x] = TiffUtils.ColorFromL8(l8, intensity, color);
                 }
             }
         }

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

@@ -34,13 +34,14 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
-                for (int x = left; x < left + width; x++)
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+                for (int x = 0; x < pixelRow.Length; x++)
                 {
                     int value = bitReader.ReadBits(this.bitsPerSample0);
                     float intensity = 1.0f - (value / this.factor);
 
                     color.FromVector4(new Vector4(intensity, intensity, intensity, 1.0f));
-                    pixels[x, y] = color;
+                    pixelRow[x] = color;
                 }
 
                 bitReader.NextRow();

src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs

@@ -266,7 +266,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
                 using TiffBaseDecompressor decompressor = TiffDecompressorsFactory.Create(this.CompressionType, this.memoryAllocator, this.PhotometricInterpretation, frame.Width, bitsPerPixel, this.Predictor, this.FaxCompressionOptions);
 
-                RgbPlanarTiffColor<TPixel> colorDecoder = TiffColorDecoderFactory<TPixel>.CreatePlanar(this.ColorType, this.BitsPerSample, this.ColorMap);
+                TiffBasePlanarColorDecoder<TPixel> colorDecoder = TiffColorDecoderFactory<TPixel>.CreatePlanar(this.ColorType, this.BitsPerSample, this.ColorMap, this.byteOrder);
 
                 for (int i = 0; i < stripsPerPlane; i++)
                 {

src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs

@@ -111,6 +111,12 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
                     switch (bitsPerChannel)
                     {
+                        case 16:
+                        {
+                            options.ColorType = TiffColorType.WhiteIsZero16;
+                            break;
+                        }
+
                         case 8:
                         {
                             options.ColorType = TiffColorType.WhiteIsZero8;
@@ -154,6 +160,12 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
                     switch (bitsPerChannel)
                     {
+                        case 16:
+                        {
+                            options.ColorType = TiffColorType.BlackIsZero16;
+                            break;
+                        }
+
                         case 8:
                         {
                             options.ColorType = TiffColorType.BlackIsZero8;

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

@@ -0,0 +1,58 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Buffers.Binary;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Tiff.Utils
+{
+    /// <summary>
+    /// Helper methods for TIFF decoding.
+    /// </summary>
+    internal static class TiffUtils
+    {
+        public static Vector4 Vector4Default { get; } = new Vector4(0.0f, 0.0f, 0.0f, 0.0f);
+
+        public static Rgba64 Rgba64Default { get; } = new Rgba64(0, 0, 0, 0);
+
+        public static L16 L16Default { get; } = new L16(0);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static ushort ConvertToShortBigEndian(ReadOnlySpan<byte> buffer) =>
+            BinaryPrimitives.ReadUInt16BigEndian(buffer);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static ushort ConvertToShortLittleEndian(ReadOnlySpan<byte> buffer) =>
+            BinaryPrimitives.ReadUInt16LittleEndian(buffer);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static TPixel ColorFromL8<TPixel>(L8 l8, byte intensity, TPixel color)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            l8.PackedValue = intensity;
+            color.FromL8(l8);
+            return color;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static TPixel ColorFromL16<TPixel>(L16 l16, ushort intensity, TPixel color)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            l16.PackedValue = intensity;
+            color.FromL16(l16);
+            return color;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static TPixel ColorFromRgba64<TPixel>(Rgba64 rgba, ulong r, ulong g, ulong b, TPixel color)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            rgba.PackedValue = r | (g << 16) | (b << 32) | (0xfffful << 48);
+            color.FromRgba64(rgba);
+            return color;
+        }
+    }
+}

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

@@ -140,7 +140,10 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
             where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider);
 
         [Theory]
+        [WithFile(Flower16BitGrayLittleEndian, PixelTypes.Rgba32)]
         [WithFile(Flower16BitGray, PixelTypes.Rgba32)]
+        [WithFile(Flower16BitGrayMinIsWhiteLittleEndian, PixelTypes.Rgba32)]
+        [WithFile(Flower16BitGrayMinIsWhiteBigEndian, PixelTypes.Rgba32)]
         public void TiffDecoder_CanDecode_16Bit<TPixel>(TestImageProvider<TPixel> provider)
             where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider);
 
@@ -163,7 +166,9 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
 
         [Theory]
         [WithFile(FlowerRgb161616Contiguous, PixelTypes.Rgba32)]
+        [WithFile(FlowerRgb161616ContiguousLittleEndian, PixelTypes.Rgba32)]
         [WithFile(FlowerRgb161616Planar, PixelTypes.Rgba32)]
+        [WithFile(FlowerRgb161616PlanarLittleEndian, PixelTypes.Rgba32)]
         [WithFile(Issues1716Rgb161616BitLittleEndian, PixelTypes.Rgba32)]
         public void TiffDecoder_CanDecode_48Bit<TPixel>(TestImageProvider<TPixel> provider)
             where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider);

tests/ImageSharp.Tests/TestImages.cs

@@ -562,7 +562,9 @@ namespace SixLabors.ImageSharp.Tests
             public const string Rgb4BitPalette = "Tiff/bike_colorpalette_4bit.tiff";
             public const string RgbPaletteDeflate = "Tiff/rgb_palette_deflate.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";
+            public const string FlowerRgb161616PlanarLittleEndian = "Tiff/flower-rgb-planar-16_lsb.tiff";
             public const string FlowerRgb141414Contiguous = "Tiff/flower-rgb-contig-14.tiff";
             public const string FlowerRgb141414Planar = "Tiff/flower-rgb-planar-14.tiff";
             public const string FlowerRgb101010Contiguous = "Tiff/flower-rgb-contig-10.tiff";
@@ -582,6 +584,9 @@ namespace SixLabors.ImageSharp.Tests
             public const string Flower12BitGray = "Tiff/flower-minisblack-12.tiff";
             public const string Flower14BitGray = "Tiff/flower-minisblack-14.tiff";
             public const string Flower16BitGray = "Tiff/flower-minisblack-16.tiff";
+            public const string Flower16BitGrayLittleEndian = "Tiff/flower-minisblack-16_lsb.tiff";
+            public const string Flower16BitGrayMinIsWhiteLittleEndian = "Tiff/flower-miniswhite-16_lsb.tiff";
+            public const string Flower16BitGrayMinIsWhiteBigEndian = "Tiff/flower-miniswhite-16.tiff";
             public const string Issues1716Rgb161616BitLittleEndian = "Tiff/Issues/Issue1716.tiff";
 
             public const string SmallRgbDeflate = "Tiff/rgb_small_deflate.tiff";

tests/Images/Input/Tiff/flower-minisblack-16_lsb.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c3806304a5453a6ec8a6795bc77b967b9aa8593288af36bbf9802f22ee27869e
+size 6588

tests/Images/Input/Tiff/flower-miniswhite-16.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d8f2c2afd8f1645717087bd2edbc3e8a46b88a54a4996c0e9350fdd652b5c382
+size 6588

tests/Images/Input/Tiff/flower-miniswhite-16_lsb.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:435c92b453587e1943940111b66afabf70307beb0e1d65e9701fd9bb753eead2
+size 6588

tests/Images/Input/Tiff/flower-rgb-contig-16_lsb.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0951a9c2207eb6864b6a19ec8513a28a874adddb37c3c06b9fd07831372924e3
+size 19150

tests/Images/Input/Tiff/flower-rgb-planar-16_lsb.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:46a60552a7ff37f2c16c43e030e7180872af712f5d9c9c7673e2547049af3da9
+size 19168