mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
3 weeks ago
11 changed files with 291 additions and 254 deletions
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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#nullable disable |
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using System.Buffers; |
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using System.Numerics; |
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using System.Runtime.InteropServices; |
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using SixLabors.ImageSharp.ColorProfiles; |
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using SixLabors.ImageSharp.ColorProfiles.Icc; |
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using SixLabors.ImageSharp.Common.Helpers; |
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using SixLabors.ImageSharp.Metadata.Profiles.Icc; |
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namespace SixLabors.ImageSharp.Formats.Jpeg.Components; |
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internal abstract partial class JpegColorConverterBase |
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{ |
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/// <summary>
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/// Converts planar jpeg component values in <paramref name="values"/> to RGB color space in-place using the given ICC profile.
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/// </summary>
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/// <param name="configuration">The configuration instance to use for the conversion.</param>
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/// <param name="values">The input/output as a stack-only <see cref="ComponentValues"/> struct.</param>
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/// <param name="profile">The ICC profile to use for the conversion.</param>
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public void ConvertToRgbInPlaceWithIcc(Configuration configuration, in ComponentValues values, IccProfile profile) |
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{ |
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Span<float> c0 = values.Component0; |
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Span<float> c1 = values.Component1; |
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Span<float> c2 = values.Component2; |
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int length = c0.Length; |
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// Four-component JPEG models need room for an interleaved CMYK or YccK source. Every conversion
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// finishes with three packed RGB floats, which safely occupy the start of the same temporary buffer.
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bool hasFourthComponent = this.ColorSpace is JpegColorSpace.Ycck |
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or JpegColorSpace.Cmyk |
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or JpegColorSpace.TiffYccK |
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or JpegColorSpace.TiffCmyk; |
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int packedComponentCount = hasFourthComponent ? 4 : 3; |
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using IMemoryOwner<float> memoryOwner = configuration.MemoryAllocator.Allocate<float>(length * packedComponentCount); |
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Span<float> packed = memoryOwner.Memory.Span; |
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if (this.ColorSpace == JpegColorSpace.Grayscale) |
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{ |
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// The single luminance plane is the ICC source, so it is normalized in place. The temporary
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// buffer is still RGB-sized because the profile conversion expands each Y sample to three lanes.
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TensorPrimitives_.Multiply(c0, 1F / this.MaximumValue, c0); |
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Span<Y> source = MemoryMarshal.Cast<float, Y>(c0); |
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Span<Rgb> destination = MemoryMarshal.Cast<float, Rgb>(packed); |
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ColorConversionOptions options = new() |
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{ |
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SourceIccProfile = profile, |
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TargetIccProfile = CompactSrgbV4Profile.Profile, |
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}; |
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ColorProfileConverter converter = new(options); |
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converter.Convert<Y, Rgb>(source, destination); |
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UnpackDeinterleave3(MemoryMarshal.Cast<float, Vector3>(packed)[..length], c0, c1, c2); |
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return; |
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} |
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// RGB and YCbCr become packed RGB before the profile transform. CMYK models remain packed CMYK,
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// because their source profile describes that four-component space rather than an intermediate RGB space.
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bool profileSourceIsCmyk = false; |
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switch (this.ColorSpace) |
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{ |
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case JpegColorSpace.RGB: |
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// JPEG RGB planes use the integer sample domain; ICC RGB values use normalized interleaved lanes.
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PackedNormalizeInterleave3(c0, c1, c2, packed, 1F / this.MaximumValue); |
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break; |
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case JpegColorSpace.YCbCr: |
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// ICC profiles rarely expose YCbCr transforms. BT.601 therefore produces RGB in the profile's
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// source space first, and that packed RGB becomes the input to the profile transform below.
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PackedNormalizeInterleave3(c0, c1, c2, packed, 1F / this.MaximumValue); |
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ColorProfileConverter yCbCrConverter = new(); |
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Span<YCbCr> yCbCr = MemoryMarshal.Cast<float, YCbCr>(packed); |
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Span<Rgb> yCbCrDestination = MemoryMarshal.Cast<float, Rgb>(packed); |
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yCbCrConverter.Convert<YCbCr, Rgb>(yCbCr, yCbCrDestination); |
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break; |
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case JpegColorSpace.Cmyk: |
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// Adobe-style JPEG CMYK stores inverted samples, while ICC consumes conventional normalized CMYK.
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PackedInvertNormalizeInterleave4(c0, c1, c2, values.Component3, packed, this.MaximumValue); |
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profileSourceIsCmyk = true; |
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break; |
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case JpegColorSpace.TiffCmyk: |
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// TIFF JPEG CMYK is already non-inverted, so only normalization and interleaving are required.
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PackedNormalizeInterleave4(c0, c1, c2, values.Component3, packed, this.MaximumValue); |
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profileSourceIsCmyk = true; |
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break; |
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case JpegColorSpace.Ycck: |
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// Adobe-style JPEG YccK is inverted before its format-defined YccK-to-CMYK transform.
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PackedInvertNormalizeInterleave4(c0, c1, c2, values.Component3, packed, this.MaximumValue); |
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ColorProfileConverter yccKConverter = new(); |
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Span<Cmyk> yccKCmyk = MemoryMarshal.Cast<float, Cmyk>(packed); |
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yccKConverter.Convert<YccK, Cmyk>(MemoryMarshal.Cast<Cmyk, YccK>(yccKCmyk), yccKCmyk); |
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profileSourceIsCmyk = true; |
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break; |
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case JpegColorSpace.TiffYccK: |
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// TIFF JPEG YccK is non-inverted, but otherwise uses the same YccK-to-CMYK transform.
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PackedNormalizeInterleave4(c0, c1, c2, values.Component3, packed, this.MaximumValue); |
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ColorProfileConverter tiffYccKConverter = new(); |
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Span<Cmyk> tiffYccKCmyk = MemoryMarshal.Cast<float, Cmyk>(packed); |
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tiffYccKConverter.Convert<YccK, Cmyk>(MemoryMarshal.Cast<Cmyk, YccK>(tiffYccKCmyk), tiffYccKCmyk); |
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profileSourceIsCmyk = true; |
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break; |
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} |
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ColorConversionOptions profileOptions = new() |
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{ |
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SourceIccProfile = profile, |
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TargetIccProfile = CompactSrgbV4Profile.Profile, |
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}; |
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ColorProfileConverter profileConverter = new(profileOptions); |
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Span<Rgb> rgb = MemoryMarshal.Cast<float, Rgb>(packed)[..length]; |
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if (profileSourceIsCmyk) |
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{ |
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// The destination aliases the first three floats of each four-float source item. The converter
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// supports this established in-place contraction, and the source span retains its original length.
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profileConverter.Convert<Cmyk, Rgb>(MemoryMarshal.Cast<float, Cmyk>(packed), rgb); |
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} |
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else |
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{ |
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profileConverter.Convert<Rgb, Rgb>(rgb, rgb); |
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} |
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// Only the packed RGB prefix is meaningful after four-component conversion; scatter it back to the
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// decoder's three planar output buffers while leaving the fourth source component untouched.
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UnpackDeinterleave3(MemoryMarshal.Cast<float, Vector3>(packed)[..length], c0, c1, c2); |
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} |
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} |
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