Add support for decoding jpeg compressed tiff images with cmyk colorspace

Author: brianpopow

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.TiffCmykScalar.cs

@@ -0,0 +1,40 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.ColorSpaces;
+using SixLabors.ImageSharp.ColorSpaces.Conversion;
+
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components;
+
+internal abstract partial class JpegColorConverterBase
+{
+    /// <summary>
+    /// Color converter for tiff images, which use the jpeg compression and CMYK colorspace.
+    /// </summary>
+    internal sealed class TiffCmykScalar : JpegColorConverterScalar
+    {
+        public TiffCmykScalar(int precision)
+            : base(JpegColorSpace.TiffCmyk, precision)
+        {
+        }
+
+        /// <inheritdoc/>
+        public override void ConvertToRgbInplace(in ComponentValues values)
+            => ConvertToRgbInplace(values, this.MaximumValue);
+
+        public override void ConvertFromRgb(in ComponentValues values, Span<float> rLane, Span<float> gLane, Span<float> bLane) => throw new NotImplementedException();
+
+        internal static void ConvertToRgbInplace(ComponentValues values, float maxValue)
+        {
+            float invMax = 1 / maxValue;
+            for (int i = 0; i < values.Component0.Length; i++)
+            {
+                Cmyk cmyk = new(values.Component0[i] * invMax, values.Component1[i] * invMax, values.Component2[i] * invMax, values.Component3[i] * invMax);
+                Rgb rgb = ColorSpaceConverter.ToRgb(in cmyk);
+                values.Component0[i] = rgb.R;
+                values.Component1[i] = rgb.G;
+                values.Component2[i] = rgb.B;
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverterBase.cs

@@ -105,8 +105,8 @@ public static JpegColorConverterBase GetConverter(JpegColorSpace colorSpace, int
     /// </summary>
     private static JpegColorConverterBase[] CreateConverters()
     {
-        // 5 color types with 2 supported precisions: 8 bit & 12 bit
-        const int colorConvertersCount = 5 * 2;
+        // 6 color types with 2 supported precisions: 8 bit & 12 bit
+        const int colorConvertersCount = 6 * 2;
 
         JpegColorConverterBase[] converters = new JpegColorConverterBase[colorConvertersCount];
 
@@ -116,13 +116,15 @@ private static JpegColorConverterBase[] CreateConverters()
         converters[2] = GetCmykConverter(8);
         converters[3] = GetGrayScaleConverter(8);
         converters[4] = GetRgbConverter(8);
+        converters[5] = GetTiffCmykConverter(8);
 
         // 12-bit converters
-        converters[5] = GetYCbCrConverter(12);
-        converters[6] = GetYccKConverter(12);
-        converters[7] = GetCmykConverter(12);
-        converters[8] = GetGrayScaleConverter(12);
-        converters[9] = GetRgbConverter(12);
+        converters[6] = GetYCbCrConverter(12);
+        converters[7] = GetYccKConverter(12);
+        converters[8] = GetCmykConverter(12);
+        converters[9] = GetGrayScaleConverter(12);
+        converters[10] = GetRgbConverter(12);
+        converters[11] = GetTiffCmykConverter(12);
 
         return converters;
     }
@@ -247,6 +249,8 @@ private static JpegColorConverterBase GetRgbConverter(int precision)
         return new RgbScalar(precision);
     }
 
+    private static JpegColorConverterBase GetTiffCmykConverter(int precision) => new TiffCmykScalar(precision);
+
     /// <summary>
     /// A stack-only struct to reference the input buffers using <see cref="ReadOnlySpan{T}"/>-s.
     /// </summary>

src/ImageSharp/Formats/Jpeg/Components/JpegColorSpace.cs

@@ -23,6 +23,11 @@ internal enum JpegColorSpace
     /// </summary>
     Cmyk,
 
+    /// <summary>
+    /// Cmyk color space with 4 components, used with tiff images, which use jpeg compression.
+    /// </summary>
+    TiffCmyk,
+
     /// <summary>
     /// Color space with 3 components.
     /// </summary>

src/ImageSharp/Formats/Tiff/Compression/Decompressors/JpegTiffCompression.cs

@@ -80,6 +80,7 @@ private void DecodeJpegData(BufferedReadStream stream, Span<byte> buffer, Cancel
 
             case TiffPhotometricInterpretation.YCbCr:
             case TiffPhotometricInterpretation.Rgb:
+            case TiffPhotometricInterpretation.Separated:
             {
                 using SpectralConverter<Rgb24> spectralConverter = new TiffJpegSpectralConverter<Rgb24>(configuration, this.photometricInterpretation);
                 HuffmanScanDecoder scanDecoder = new(stream, spectralConverter, cancellationToken);

src/ImageSharp/Formats/Tiff/Compression/Decompressors/TiffJpegSpectralConverter{TPixel}.cs

@@ -36,14 +36,17 @@ protected override JpegColorConverterBase GetColorConverter(JpegFrame frame, IRa
     }
 
     /// <summary>
-    /// This converter must be used only for RGB and YCbCr color spaces for performance reasons.
+    /// Photometric interpretation Rgb and YCbCr will be mapped to RGB colorspace, which means the jpeg decompression will leave the data as is (no color conversion).
+    /// The color conversion will be done after the decompression. For Separated/CMYK, the jpeg color converter will handle the color conversion,
+    /// since the jpeg color converter needs to return RGB data and cannot return 4 component data.
     /// For grayscale images <see cref="GrayJpegSpectralConverter{TPixel}"/> must be used.
     /// </summary>
     private static JpegColorSpace GetJpegColorSpaceFromPhotometricInterpretation(TiffPhotometricInterpretation interpretation)
         => interpretation switch
         {
             TiffPhotometricInterpretation.Rgb => JpegColorSpace.RGB,
             TiffPhotometricInterpretation.YCbCr => JpegColorSpace.RGB,
+            TiffPhotometricInterpretation.Separated => JpegColorSpace.TiffCmyk,
             _ => throw new InvalidImageContentException($"Invalid tiff photometric interpretation for jpeg encoding: {interpretation}"),
         };
 }

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

@@ -4,6 +4,7 @@
 using System.Numerics;
 using SixLabors.ImageSharp.ColorSpaces;
 using SixLabors.ImageSharp.ColorSpaces.Conversion;
+using SixLabors.ImageSharp.Formats.Tiff.Compression;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -14,11 +15,33 @@ internal class CmykTiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
 {
     private const float Inv255 = 1 / 255.0f;
 
+    private readonly TiffDecoderCompressionType compression;
+
+    public CmykTiffColor(TiffDecoderCompressionType compression) => this.compression = compression;
+
     /// <inheritdoc/>
     public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
     {
         TPixel color = default;
         int offset = 0;
+
+        if (this.compression == TiffDecoderCompressionType.Jpeg)
+        {
+            for (int y = top; y < top + height; y++)
+            {
+                Span<TPixel> pixelRow = pixels.DangerousGetRowSpan(y).Slice(left, width);
+                for (int x = 0; x < pixelRow.Length; x++)
+                {
+                    color.FromVector4(new Vector4(data[offset] * Inv255, data[offset + 1] * Inv255, data[offset + 2] * Inv255, 1.0f));
+                    pixelRow[x] = color;
+
+                    offset += 3;
+                }
+            }
+
+            return;
+        }
+
         for (int y = top; y < top + height; y++)
         {
             Span<TPixel> pixelRow = pixels.DangerousGetRowSpan(y).Slice(left, width);

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

@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Formats.Tiff.Compression;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -19,6 +20,7 @@ public static TiffBaseColorDecoder<TPixel> Create(
         Rational[] referenceBlackAndWhite,
         Rational[] ycbcrCoefficients,
         ushort[] ycbcrSubSampling,
+        TiffDecoderCompressionType compression,
         ByteOrder byteOrder)
     {
         switch (colorType)
@@ -410,7 +412,7 @@ public static TiffBaseColorDecoder<TPixel> Create(
                     && bitsPerSample.Channel1 == 8
                     && bitsPerSample.Channel0 == 8,
                     "bitsPerSample");
-                return new CmykTiffColor<TPixel>();
+                return new CmykTiffColor<TPixel>(compression);
 
             default:
                 throw TiffThrowHelper.InvalidColorType(colorType.ToString());

src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs

@@ -703,6 +703,7 @@ private TiffBaseColorDecoder<TPixel> CreateChunkyColorDecoder<TPixel>()
             this.ReferenceBlackAndWhite,
             this.YcbcrCoefficients,
             this.YcbcrSubSampling,
+            this.CompressionType,
             this.byteOrder);
 
     private TiffBasePlanarColorDecoder<TPixel> CreatePlanarColorDecoder<TPixel>()

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

@@ -2,7 +2,6 @@
 // Licensed under the Six Labors Split License.
 
 // ReSharper disable InconsistentNaming
-using System.Runtime.InteropServices;
 using System.Runtime.Intrinsics.X86;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Tiff;
@@ -309,6 +308,7 @@ public void TiffDecoder_CanDecode_CieLab<TPixel>(TestImageProvider<TPixel> provi
     [Theory]
     [WithFile(Cmyk, PixelTypes.Rgba32)]
     [WithFile(CmykLzwPredictor, PixelTypes.Rgba32)]
+    [WithFile(CmykJpeg, PixelTypes.Rgba32)]
     public void TiffDecoder_CanDecode_Cmyk<TPixel>(TestImageProvider<TPixel> provider)
         where TPixel : unmanaged, IPixel<TPixel>
     {

tests/ImageSharp.Tests/TestImages.cs

@@ -968,6 +968,7 @@ public static class Tiff
         public const string Cmyk = "Tiff/Cmyk.tiff";
         public const string Cmyk64BitDeflate = "Tiff/cmyk_deflate_64bit.tiff";
         public const string CmykLzwPredictor = "Tiff/Cmyk-lzw-predictor.tiff";
+        public const string CmykJpeg = "Tiff/Cmyk-jpeg.tiff";
 
         public const string Issues1716Rgb161616BitLittleEndian = "Tiff/Issues/Issue1716.tiff";
         public const string Issues1891 = "Tiff/Issues/Issue1891.tiff";