Add support for decoding ycbcr tiff's with planar configuration

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

@@ -154,7 +154,13 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             }
         }
 
-        public static TiffBasePlanarColorDecoder<TPixel> CreatePlanar(TiffColorType colorType, TiffBitsPerSample bitsPerSample, ushort[] colorMap, ByteOrder byteOrder)
+        public static TiffBasePlanarColorDecoder<TPixel> CreatePlanar(
+            TiffColorType colorType,
+            TiffBitsPerSample bitsPerSample,
+            ushort[] colorMap,
+            Rational[] referenceBlackAndWhite,
+            Rational[] ycbcrCoefficients,
+            ByteOrder byteOrder)
         {
             switch (colorType)
             {
@@ -167,6 +173,9 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
                     return new RgbPlanarTiffColor<TPixel>(bitsPerSample);
 
+                case TiffColorType.YCbCrPlanar:
+                    return new YCbCrPlanarTiffColor<TPixel>(referenceBlackAndWhite, ycbcrCoefficients);
+
                 default:
                     throw TiffThrowHelper.InvalidColorType(colorType.ToString());
             }

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

@@ -108,6 +108,14 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
         /// </summary>
         RgbPlanar,
 
-        YCbCr
+        /// <summary>
+        /// The pixels are stored in YCbCr format.
+        /// </summary>
+        YCbCr,
+
+        /// <summary>
+        /// The pixels are stored in YCbCr format as planar.
+        /// </summary>
+        YCbCrPlanar
     }
 }

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

@@ -0,0 +1,121 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Runtime.CompilerServices;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
+{
+    /// <summary>
+    /// Converts YCbCr data to rgb data.
+    /// </summary>
+    internal class YCbCrConverter
+    {
+        private readonly CodingRangeExpander yExpander;
+        private readonly CodingRangeExpander cbExpander;
+        private readonly CodingRangeExpander crExpander;
+        private readonly YCbCrToRgbConverter converter;
+
+        private static readonly Rational[] DefaultLuma =
+        {
+            new Rational(299, 1000),
+            new Rational(587, 1000),
+            new Rational(114, 1000)
+        };
+
+        private static readonly Rational[] DefaultReferenceBlackWhite =
+        {
+            new Rational(0, 1), new Rational(255, 1),
+            new Rational(128, 1), new Rational(255, 1),
+            new Rational(128, 1), new Rational(255, 1)
+        };
+
+        public YCbCrConverter(Rational[] referenceBlackAndWhite, Rational[] coefficients)
+        {
+            referenceBlackAndWhite ??= DefaultReferenceBlackWhite;
+            coefficients ??= DefaultLuma;
+
+            if (referenceBlackAndWhite.Length != 6)
+            {
+                TiffThrowHelper.ThrowImageFormatException("reference black and white array should have 6 entry's");
+            }
+
+            if (coefficients.Length != 3)
+            {
+                TiffThrowHelper.ThrowImageFormatException("luma coefficients array should have 6 entry's");
+            }
+
+            this.yExpander = new CodingRangeExpander(referenceBlackAndWhite[0], referenceBlackAndWhite[1], 255);
+            this.cbExpander = new CodingRangeExpander(referenceBlackAndWhite[2], referenceBlackAndWhite[3], 127);
+            this.crExpander = new CodingRangeExpander(referenceBlackAndWhite[4], referenceBlackAndWhite[5], 127);
+            this.converter = new YCbCrToRgbConverter(coefficients[0], coefficients[1], coefficients[2]);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public Rgba32 ConvertToRgba32(byte y, byte cb, byte cr)
+        {
+            float yExpanded = this.yExpander.Expand(y);
+            float cbExpanded = this.cbExpander.Expand(cb);
+            float crExpanded = this.crExpander.Expand(cr);
+
+            Rgba32 rgba = this.converter.Convert(yExpanded, cbExpanded, crExpanded);
+
+            return rgba;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static byte RoundAndClampTo8Bit(float value)
+        {
+            int input = (int)MathF.Round(value);
+            return (byte)Math.Min(Math.Max(input, 0), 255);
+        }
+
+        private readonly struct CodingRangeExpander
+        {
+            private readonly float f1;
+            private readonly float f2;
+
+            public CodingRangeExpander(Rational referenceBlack, Rational referenceWhite, int codingRange)
+            {
+                float black = referenceBlack.ToSingle();
+                float white = referenceWhite.ToSingle();
+                this.f1 = codingRange / (white - black);
+                this.f2 = this.f1 * black;
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            public float Expand(float code) => (code * this.f1) - this.f2;
+        }
+
+        private readonly struct YCbCrToRgbConverter
+        {
+            private readonly float cr2R;
+            private readonly float cb2B;
+            private readonly float y2G;
+            private readonly float cr2G;
+            private readonly float cb2G;
+
+            public YCbCrToRgbConverter(Rational lumaRed, Rational lumaGreen, Rational lumaBlue)
+            {
+                this.cr2R = 2 - (2 * lumaRed.ToSingle());
+                this.cb2B = 2 - (2 * lumaBlue.ToSingle());
+                this.y2G = (1 - lumaBlue.ToSingle() - lumaRed.ToSingle()) / lumaGreen.ToSingle();
+                this.cr2G = 2 * lumaRed.ToSingle() * (lumaRed.ToSingle() - 1) / lumaGreen.ToSingle();
+                this.cb2G = 2 * lumaBlue.ToSingle() * (lumaBlue.ToSingle() - 1) / lumaGreen.ToSingle();
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            public Rgba32 Convert(float y, float cb, float cr)
+            {
+                var pixel = default(Rgba32);
+                pixel.R = RoundAndClampTo8Bit((cr * this.cr2R) + y);
+                pixel.G = RoundAndClampTo8Bit((this.y2G * y) + (this.cr2G * cr) + (this.cb2G * cb));
+                pixel.B = RoundAndClampTo8Bit((cb * this.cb2B) + y);
+                pixel.A = byte.MaxValue;
+
+                return pixel;
+            }
+        }
+    }
+}

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

@@ -0,0 +1,40 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Buffers;
+using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
+{
+    internal class YCbCrPlanarTiffColor<TPixel> : TiffBasePlanarColorDecoder<TPixel>
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        private readonly YCbCrConverter converter;
+
+        public YCbCrPlanarTiffColor(Rational[] referenceBlackAndWhite, Rational[] coefficients) => this.converter = new YCbCrConverter(referenceBlackAndWhite, coefficients);
+
+        /// <inheritdoc/>
+        public override void Decode(IMemoryOwner<byte>[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
+        {
+            Span<byte> yData = data[0].GetSpan();
+            Span<byte> cbData = data[1].GetSpan();
+            Span<byte> crData = data[2].GetSpan();
+
+            var color = default(TPixel);
+            int offset = 0;
+            for (int y = top; y < top + height; y++)
+            {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
+                for (int x = 0; x < pixelRow.Length; x++)
+                {
+                    Rgba32 rgba = this.converter.ConvertToRgba32(yData[offset], cbData[offset], crData[offset]);
+                    color.FromRgba32(rgba);
+                    pixelRow[x] = color;
+                    offset++;
+                }
+            }
+        }
+    }
+}

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

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -11,10 +10,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
     internal class YCbCrTiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
-        private readonly CodingRangeExpander yExpander;
-        private readonly CodingRangeExpander cbExpander;
-        private readonly CodingRangeExpander crExpander;
-        private readonly YCbCrToRgbConverter converter;
+        private readonly YCbCrConverter converter;
 
         private static readonly Rational[] DefaultLuma =
         {
@@ -45,10 +41,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 TiffThrowHelper.ThrowImageFormatException("luma coefficients array should have 6 entry's");
             }
 
-            this.yExpander = new CodingRangeExpander(referenceBlackAndWhite[0], referenceBlackAndWhite[1], 255);
-            this.cbExpander = new CodingRangeExpander(referenceBlackAndWhite[2], referenceBlackAndWhite[3], 127);
-            this.crExpander = new CodingRangeExpander(referenceBlackAndWhite[4], referenceBlackAndWhite[5], 127);
-            this.converter = new YCbCrToRgbConverter(coefficients[0], coefficients[1], coefficients[2]);
+            this.converter = new YCbCrConverter(referenceBlackAndWhite, coefficients);
         }
 
         /// <inheritdoc/>
@@ -61,78 +54,12 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                 Span<TPixel> pixelRow = pixels.GetRowSpan(y).Slice(left, width);
                 for (int x = 0; x < pixelRow.Length; x++)
                 {
-                    Rgba32 rgba = this.ConvertToRgba32(data[offset], data[offset + 1], data[offset + 2]);
+                    Rgba32 rgba = this.converter.ConvertToRgba32(data[offset], data[offset + 1], data[offset + 2]);
                     color.FromRgba32(rgba);
                     pixelRow[x] = color;
                     offset += 3;
                 }
             }
         }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private Rgba32 ConvertToRgba32(byte y, byte cb, byte cr)
-        {
-            float yExpanded = this.yExpander.Expand(y);
-            float cbExpanded = this.cbExpander.Expand(cb);
-            float crExpanded = this.crExpander.Expand(cr);
-
-            Rgba32 rgba = this.converter.Convert(yExpanded, cbExpanded, crExpanded);
-
-            return rgba;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static byte RoundAndClampTo8Bit(float value)
-        {
-            int input = (int)MathF.Round(value);
-            return (byte)Math.Min(Math.Max(input, 0), 255);
-        }
-
-        private readonly struct CodingRangeExpander
-        {
-            private readonly float f1;
-            private readonly float f2;
-
-            public CodingRangeExpander(Rational referenceBlack, Rational referenceWhite, int codingRange)
-            {
-                float black = referenceBlack.ToSingle();
-                float white = referenceWhite.ToSingle();
-                this.f1 = codingRange / (white - black);
-                this.f2 = this.f1 * black;
-            }
-
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            public float Expand(float code) => (code * this.f1) - this.f2;
-        }
-
-        private readonly struct YCbCrToRgbConverter
-        {
-            private readonly float cr2R;
-            private readonly float cb2B;
-            private readonly float y2G;
-            private readonly float cr2G;
-            private readonly float cb2G;
-
-            public YCbCrToRgbConverter(Rational lumaRed, Rational lumaGreen, Rational lumaBlue)
-            {
-                this.cr2R = 2 - (2 * lumaRed.ToSingle());
-                this.cb2B = 2 - (2 * lumaBlue.ToSingle());
-                this.y2G = (1 - lumaBlue.ToSingle() - lumaRed.ToSingle()) / lumaGreen.ToSingle();
-                this.cr2G = 2 * lumaRed.ToSingle() * (lumaRed.ToSingle() - 1) / lumaGreen.ToSingle();
-                this.cb2G = 2 * lumaBlue.ToSingle() * (lumaBlue.ToSingle() - 1) / lumaGreen.ToSingle();
-            }
-
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            public Rgba32 Convert(float y, float cb, float cr)
-            {
-                var pixel = default(Rgba32);
-                pixel.R = RoundAndClampTo8Bit((cr * this.cr2R) + y);
-                pixel.G = RoundAndClampTo8Bit((this.y2G * y) + (this.cr2G * cr) + (this.cb2G * cb));
-                pixel.B = RoundAndClampTo8Bit((cb * this.cb2B) + y);
-                pixel.A = byte.MaxValue;
-
-                return pixel;
-            }
-        }
     }
 }

src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs

@@ -268,9 +268,22 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                     stripBuffers[stripIndex] = this.memoryAllocator.Allocate<byte>(uncompressedStripSize);
                 }
 
-                using TiffBaseDecompressor decompressor = TiffDecompressorsFactory.Create(this.CompressionType, this.memoryAllocator, this.PhotometricInterpretation, frame.Width, bitsPerPixel, this.Predictor, this.FaxCompressionOptions);
-
-                TiffBasePlanarColorDecoder<TPixel> colorDecoder = TiffColorDecoderFactory<TPixel>.CreatePlanar(this.ColorType, this.BitsPerSample, this.ColorMap, this.byteOrder);
+                using TiffBaseDecompressor decompressor = TiffDecompressorsFactory.Create(
+                    this.CompressionType,
+                    this.memoryAllocator,
+                    this.PhotometricInterpretation,
+                    frame.Width,
+                    bitsPerPixel,
+                    this.Predictor,
+                    this.FaxCompressionOptions);
+
+                TiffBasePlanarColorDecoder<TPixel> colorDecoder = TiffColorDecoderFactory<TPixel>.CreatePlanar(
+                    this.ColorType,
+                    this.BitsPerSample,
+                    this.ColorMap,
+                    this.ReferenceBlackAndWhite,
+                    this.YcbcrCoefficients,
+                    this.byteOrder);
 
                 for (int i = 0; i < stripsPerPlane; i++)
                 {

src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs

@@ -274,7 +274,8 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                         TiffThrowHelper.ThrowNotSupported("The number of samples in the TIFF BitsPerSample entry is not supported.");
                     }
 
-                    options.ColorType = TiffColorType.YCbCr;
+                    options.ColorType = options.PlanarConfiguration == TiffPlanarConfiguration.Chunky ? TiffColorType.YCbCr : TiffColorType.YCbCrPlanar;
+
                     break;
                 }
 

tests/ImageSharp.Tests/TestImages.cs

@@ -576,6 +576,7 @@ namespace SixLabors.ImageSharp.Tests
             public const string FlowerRgb888Planar6Strips = "Tiff/flower-rgb-planar-08-6strips.tiff";
             public const string FlowerRgb888Planar15Strips = "Tiff/flower-rgb-planar-08-15strips.tiff";
             public const string FlowerYCbCr888Contiguous = "Tiff/flower_ycbcr_contig-08.tiff";
+            public const string FlowerYCbCr888Planar = "Tiff/flower_ycbcr_planar-08.tiff";
             public const string FlowerRgb444Contiguous = "Tiff/flower-rgb-contig-04.tiff";
             public const string FlowerRgb444Planar = "Tiff/flower-rgb-planar-04.tiff";
             public const string FlowerRgb222Contiguous = "Tiff/flower-rgb-contig-02.tiff";

tests/Images/Input/Tiff/flower-ycbcr-planar-08.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:cdc4d8033214a6737f41c4e32d9314db77b3b1ae14515496f10468047390f6c5
+size 10042