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JimBobSquarePantsJimBobSquarePants
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Merge pull request #2127 from SixLabors/bp/cielab
Add support for decoding tiff images with CieLab color space
2 parents e29a9e8 + a258c47 commit 29320a6

17 files changed

Lines changed: 188 additions & 3 deletions

‎src/ImageSharp/Formats/Tiff/Compression/HorizontalPredictor.cs‎

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@@ -41,6 +41,7 @@ public static void Undo(Span<byte> pixelBytes, int width, TiffColorType colorTyp
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UndoGray32Bit(pixelBytes, width, isBigEndian);
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break;
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case TiffColorType.Rgb888:
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case TiffColorType.CieLab:
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UndoRgb24Bit(pixelBytes, width);
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break;
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case TiffColorType.Rgba8888:

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

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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using System;
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using System.Buffers;
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using System.Numerics;
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using SixLabors.ImageSharp.ColorSpaces;
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using SixLabors.ImageSharp.ColorSpaces.Conversion;
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using SixLabors.ImageSharp.Memory;
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using SixLabors.ImageSharp.PixelFormats;
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namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
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{
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/// <summary>
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/// Implements decoding pixel data with photometric interpretation of type 'CieLab' with the planar configuration.
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/// </summary>
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internal class CieLabPlanarTiffColor<TPixel> : TiffBasePlanarColorDecoder<TPixel>
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where TPixel : unmanaged, IPixel<TPixel>
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{
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private static readonly ColorSpaceConverter ColorSpaceConverter = new();
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private const float Inv255 = 1.0f / 255.0f;
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/// <inheritdoc/>
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public override void Decode(IMemoryOwner<byte>[] data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
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{
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Span<byte> l = data[0].GetSpan();
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Span<byte> a = data[1].GetSpan();
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Span<byte> b = data[2].GetSpan();
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var color = default(TPixel);
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int offset = 0;
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for (int y = top; y < top + height; y++)
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{
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Span<TPixel> pixelRow = pixels.DangerousGetRowSpan(y).Slice(left, width);
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for (int x = 0; x < pixelRow.Length; x++)
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{
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var lab = new CieLab((l[offset] & 0xFF) * 100f * Inv255, (sbyte)a[offset], (sbyte)b[offset]);
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var rgb = ColorSpaceConverter.ToRgb(lab);
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color.FromVector4(new Vector4(rgb.R, rgb.G, rgb.B, 1.0f));
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pixelRow[x] = color;
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offset++;
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}
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}
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}
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}
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}

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

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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using System;
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using System.Numerics;
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using SixLabors.ImageSharp.ColorSpaces;
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using SixLabors.ImageSharp.ColorSpaces.Conversion;
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using SixLabors.ImageSharp.Memory;
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using SixLabors.ImageSharp.PixelFormats;
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namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
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{
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/// <summary>
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/// Implements decoding pixel data with photometric interpretation of type 'CieLab'.
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/// </summary>
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internal class CieLabTiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
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where TPixel : unmanaged, IPixel<TPixel>
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{
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private static readonly ColorSpaceConverter ColorSpaceConverter = new();
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private const float Inv255 = 1.0f / 255.0f;
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/// <inheritdoc/>
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public override void Decode(ReadOnlySpan<byte> data, Buffer2D<TPixel> pixels, int left, int top, int width, int height)
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{
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var color = default(TPixel);
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int offset = 0;
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for (int y = top; y < top + height; y++)
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{
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Span<TPixel> pixelRow = pixels.DangerousGetRowSpan(y).Slice(left, width);
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for (int x = 0; x < pixelRow.Length; x++)
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{
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float l = (data[offset] & 0xFF) * 100f * Inv255;
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var lab = new CieLab(l, (sbyte)data[offset + 1], (sbyte)data[offset + 2]);
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var rgb = ColorSpaceConverter.ToRgb(lab);
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color.FromVector4(new Vector4(rgb.R, rgb.G, rgb.B, 1.0f));
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pixelRow[x] = color;
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offset += 3;
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}
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}
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}
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}
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}

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

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@@ -385,8 +385,23 @@ public static TiffBaseColorDecoder<TPixel> Create(
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return new PaletteTiffColor<TPixel>(bitsPerSample, colorMap);
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case TiffColorType.YCbCr:
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DebugGuard.IsTrue(
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bitsPerSample.Channels == 3
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&& bitsPerSample.Channel2 == 8
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&& bitsPerSample.Channel1 == 8
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&& bitsPerSample.Channel0 == 8,
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"bitsPerSample");
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return new YCbCrTiffColor<TPixel>(memoryAllocator, referenceBlackAndWhite, ycbcrCoefficients, ycbcrSubSampling);
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396+
case TiffColorType.CieLab:
397+
DebugGuard.IsTrue(
398+
bitsPerSample.Channels == 3
399+
&& bitsPerSample.Channel2 == 8
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&& bitsPerSample.Channel1 == 8
401+
&& bitsPerSample.Channel0 == 8,
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"bitsPerSample");
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return new CieLabTiffColor<TPixel>();
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default:
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throw TiffThrowHelper.InvalidColorType(colorType.ToString());
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}
@@ -415,6 +430,9 @@ public static TiffBasePlanarColorDecoder<TPixel> CreatePlanar(
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case TiffColorType.YCbCrPlanar:
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return new YCbCrPlanarTiffColor<TPixel>(referenceBlackAndWhite, ycbcrCoefficients, ycbcrSubSampling);
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433+
case TiffColorType.CieLabPlanar:
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return new CieLabPlanarTiffColor<TPixel>();
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case TiffColorType.Rgb161616Planar:
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DebugGuard.IsTrue(colorMap == null, "colorMap");
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return new Rgb16PlanarTiffColor<TPixel>(byteOrder == ByteOrder.BigEndian);

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

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@@ -276,6 +276,16 @@ internal enum TiffColorType
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/// <summary>
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/// The pixels are stored in YCbCr format as planar.
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/// </summary>
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YCbCrPlanar
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YCbCrPlanar,
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/// <summary>
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/// The pixels are stored in CieLab format.
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/// </summary>
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CieLab,
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/// <summary>
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/// The pixels are stored in CieLab format as planar.
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/// </summary>
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CieLabPlanar,
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}
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}

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

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@@ -9,6 +9,9 @@
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namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
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{
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/// <summary>
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/// Implements decoding pixel data with photometric interpretation of type 'YCbCr' with the planar configuration.
14+
/// </summary>
1215
internal class YCbCrPlanarTiffColor<TPixel> : TiffBasePlanarColorDecoder<TPixel>
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where TPixel : unmanaged, IPixel<TPixel>
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{

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

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@@ -9,6 +9,9 @@
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namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
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{
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/// <summary>
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/// Implements decoding pixel data with photometric interpretation of type 'YCbCr'.
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/// </summary>
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internal class YCbCrTiffColor<TPixel> : TiffBaseColorDecoder<TPixel>
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where TPixel : unmanaged, IPixel<TPixel>
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{

‎src/ImageSharp/Formats/Tiff/README.md‎

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@@ -55,7 +55,7 @@
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|TransparencyMask | | | |
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|Separated (TIFF Extension) | | | |
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|YCbCr (TIFF Extension) | | Y | |
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|CieLab (TIFF Extension) | | | |
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|CieLab (TIFF Extension) | | Y | |
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|IccLab (TechNote 1) | | | |
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### Baseline TIFF Tags

‎src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs‎

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Original file line numberDiff line numberDiff line change
@@ -381,7 +381,7 @@ private static void ParseColorType(this TiffDecoderCore options, ExifProfile exi
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options.ColorMap = exifProfile.GetValue(ExifTag.ColorMap)?.Value;
382382
if (options.BitsPerSample.Channels != 3)
383383
{
384-
TiffThrowHelper.ThrowNotSupported("The number of samples in the TIFF BitsPerSample entry is not supported.");
384+
TiffThrowHelper.ThrowNotSupported("The number of samples in the TIFF BitsPerSample entry is not supported for YCbCr images.");
385385
}
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387387
ushort bitsPerChannel = options.BitsPerSample.Channel0;
@@ -395,6 +395,24 @@ private static void ParseColorType(this TiffDecoderCore options, ExifProfile exi
395395
break;
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}
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398+
case TiffPhotometricInterpretation.CieLab:
399+
{
400+
if (options.BitsPerSample.Channels != 3)
401+
{
402+
TiffThrowHelper.ThrowNotSupported("The number of samples in the TIFF BitsPerSample entry is not supported for CieLab images.");
403+
}
404+
405+
ushort bitsPerChannel = options.BitsPerSample.Channel0;
406+
if (bitsPerChannel != 8)
407+
{
408+
TiffThrowHelper.ThrowNotSupported("Only 8 bits per channel is supported for CieLab images.");
409+
}
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411+
options.ColorType = options.PlanarConfiguration == TiffPlanarConfiguration.Chunky ? TiffColorType.CieLab : TiffColorType.CieLabPlanar;
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break;
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}
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default:
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{
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TiffThrowHelper.ThrowNotSupported($"The specified TIFF photometric interpretation is not supported: {options.PhotometricInterpretation}");

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

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@@ -318,6 +318,20 @@ public void TiffDecoder_CanDecode_YCbCr_24Bit<TPixel>(TestImageProvider<TPixel>
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image.CompareToReferenceOutput(ImageComparer.Exact, provider);
319319
}
320320

321+
[Theory]
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[WithFile(CieLab, PixelTypes.Rgba32)]
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[WithFile(CieLabPlanar, PixelTypes.Rgba32)]
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[WithFile(CieLabLzwPredictor, PixelTypes.Rgba32)]
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public void TiffDecoder_CanDecode_CieLab<TPixel>(TestImageProvider<TPixel> provider)
326+
where TPixel : unmanaged, IPixel<TPixel>
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{
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// Note: The image from MagickReferenceDecoder does not look right, maybe we are doing something wrong
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// converting the pixel data from Magick.NET to our format with CieLab?
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using Image<TPixel> image = provider.GetImage();
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image.DebugSave(provider);
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image.CompareToReferenceOutput(ImageComparer.Exact, provider);
333+
}
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[Theory]
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[WithFile(FlowerRgb101010Contiguous, PixelTypes.Rgba32)]
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[WithFile(FlowerRgb101010Planar, PixelTypes.Rgba32)]

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