mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
1 year ago
20 changed files with 400 additions and 26 deletions
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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.Numerics; |
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namespace SixLabors.ImageSharp.ColorProfiles; |
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/// <summary>
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/// Provides standard Y (luma) coefficient sets for weighted RGB conversions.
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/// </summary>
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public static class KnownYCoefficients |
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{ |
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/// <summary>
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/// ITU-R BT.601 (SD video standard).
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/// </summary>
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public static readonly Vector3 BT601 = new(0.299F, 0.587F, 0.114F); |
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/// <summary>
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/// ITU-R BT.709 (HD video, sRGB standard).
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/// </summary>
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public static readonly Vector3 BT709 = new(0.2126F, 0.7152F, 0.0722F); |
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/// <summary>
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/// ITU-R BT.2020 (UHD/4K video standard).
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/// </summary>
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public static readonly Vector3 BT2020 = new(0.2627F, 0.6780F, 0.0593F); |
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} |
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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.Numerics; |
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using System.Runtime.CompilerServices; |
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using System.Runtime.InteropServices; |
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namespace SixLabors.ImageSharp.ColorProfiles; |
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/// <summary>
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/// Represents a Y (luminance) color.
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/// </summary>
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[StructLayout(LayoutKind.Sequential)] |
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public readonly struct Y : IColorProfile<Y, Rgb> |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="Y"/> struct.
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/// </summary>
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/// <param name="l">The luminance component.</param>
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public Y(float l) => this.L = l; |
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/// <summary>
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/// Gets the luminance component.
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/// </summary>
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/// <remarks>A value ranging between 0 and 1.</remarks>
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public float L { get; } |
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/// <summary>
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/// Compares two <see cref="Y"/> objects for equality.
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/// </summary>
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/// <param name="left">The <see cref="Y"/> on the left side of the operand.</param>
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/// <param name="right">The <see cref="Y"/> on the right side of the operand.</param>
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/// <returns>
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/// True if the current left is equal to the <paramref name="right"/> parameter; otherwise, false.
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/// </returns>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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public static bool operator ==(Y left, Y right) => left.Equals(right); |
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/// <summary>
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/// Compares two <see cref="Y"/> objects for inequality.
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/// </summary>
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/// <param name="left">The <see cref="Y"/> on the left side of the operand.</param>
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/// <param name="right">The <see cref="Y"/> on the right side of the operand.</param>
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/// <returns>
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/// True if the current left is unequal to the <paramref name="right"/> parameter; otherwise, false.
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/// </returns>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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public static bool operator !=(Y left, Y right) => !left.Equals(right); |
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/// <inheritdoc/>
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public static Y FromProfileConnectingSpace(ColorConversionOptions options, in Rgb source) |
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{ |
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Vector3 weights = options.YCoefficients; |
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float l = (weights.X * source.R) + (weights.Y * source.G) + (weights.Z * source.B); |
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return new Y(l); |
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} |
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/// <inheritdoc/>
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public static void FromProfileConnectionSpace(ColorConversionOptions options, ReadOnlySpan<Rgb> source, Span<Y> destination) |
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{ |
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Guard.DestinationShouldNotBeTooShort(source, destination, nameof(destination)); |
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// TODO: We can optimize this by using SIMD
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for (int i = 0; i < source.Length; i++) |
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{ |
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Rgb rgb = source[i]; |
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destination[i] = FromProfileConnectingSpace(options, in rgb); |
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} |
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} |
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/// <inheritdoc/>
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public Vector4 ToScaledVector4() => new(this.L); |
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/// <inheritdoc/>
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public static Y FromScaledVector4(Vector4 source) => new(source.X); |
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/// <inheritdoc/>
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public static void ToScaledVector4(ReadOnlySpan<Y> source, Span<Vector4> destination) |
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{ |
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Guard.DestinationShouldNotBeTooShort(source, destination, nameof(destination)); |
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// TODO: Optimize via SIMD
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for (int i = 0; i < source.Length; i++) |
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{ |
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destination[i] = source[i].ToScaledVector4(); |
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} |
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} |
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/// <inheritdoc/>
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public static void FromScaledVector4(ReadOnlySpan<Vector4> source, Span<Y> destination) |
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{ |
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Guard.DestinationShouldNotBeTooShort(source, destination, nameof(destination)); |
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// TODO: Optimize via SIMD
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for (int i = 0; i < source.Length; i++) |
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{ |
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destination[i] = FromScaledVector4(source[i]); |
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} |
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} |
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/// <inheritdoc/>
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public Rgb ToProfileConnectingSpace(ColorConversionOptions options) |
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=> new(this.L, this.L, this.L); |
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/// <inheritdoc/>
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public static void ToProfileConnectionSpace(ColorConversionOptions options, ReadOnlySpan<Y> source, Span<Rgb> destination) |
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{ |
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Guard.DestinationShouldNotBeTooShort(source, destination, nameof(destination)); |
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// TODO: We can optimize this by using SIMD
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for (int i = 0; i < source.Length; i++) |
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{ |
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destination[i] = source[i].ToProfileConnectingSpace(options); |
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} |
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} |
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/// <inheritdoc/>
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public static ChromaticAdaptionWhitePointSource GetChromaticAdaptionWhitePointSource() |
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=> ChromaticAdaptionWhitePointSource.RgbWorkingSpace; |
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/// <inheritdoc/>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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public override int GetHashCode() |
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=> this.L.GetHashCode(); |
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/// <inheritdoc/>
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public override string ToString() |
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=> FormattableString.Invariant($"Y({this.L:#0.##})"); |
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/// <inheritdoc/>
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public override bool Equals(object? obj) |
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=> obj is Y other && this.Equals(other); |
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/// <inheritdoc/>
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public bool Equals(Y other) => this.L == other.L; |
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} |
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using SixLabors.ImageSharp.ColorProfiles; |
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namespace SixLabors.ImageSharp.Tests.ColorProfiles; |
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/// <summary>
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/// Tests <see cref="Rgb"/>-<see cref="Y"/> conversions.
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/// </summary>
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/// <remarks>
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/// Test data generated mathematically
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/// </remarks>
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public class RbgAndYConversionTests |
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{ |
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private static readonly ApproximateColorProfileComparer Comparer = new(.001F); |
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[Theory] |
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[InlineData(0F, 0F, 0F, 0F)] |
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[InlineData(0.5F, 0.5F, 0.5F, 0.5F)] |
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[InlineData(1F, 1F, 1F, 1F)] |
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public void Convert_Y_To_Rgb(float y, float r, float g, float b) |
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{ |
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// Arrange
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Y input = new(y); |
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Rgb expected = new(r, g, b); |
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ColorProfileConverter converter = new(); |
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Span<Y> inputSpan = new Y[5]; |
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inputSpan.Fill(input); |
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Span<Rgb> actualSpan = new Rgb[5]; |
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// Act
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Rgb actual = converter.Convert<Y, Rgb>(input); |
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converter.Convert<Y, Rgb>(inputSpan, actualSpan); |
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// Assert
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Assert.Equal(expected, actual, Comparer); |
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for (int i = 0; i < actualSpan.Length; i++) |
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{ |
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Assert.Equal(expected, actualSpan[i], Comparer); |
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} |
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} |
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[Theory] |
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[InlineData(0F, 0F, 0F, 0F)] |
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[InlineData(0.5F, 0.5F, 0.5F, 0.5F)] |
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[InlineData(1F, 1F, 1F, 1F)] |
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public void Convert_Rgb_To_Y_BT601(float r, float g, float b, float y) |
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{ |
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ColorConversionOptions options = new() |
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{ |
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YCoefficients = KnownYCoefficients.BT601 |
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}; |
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Convert_Rgb_To_Y_Core(r, g, b, y, options); |
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} |
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[Theory] |
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[InlineData(0F, 0F, 0F, 0F)] |
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[InlineData(0.5F, 0.5F, 0.5F, 0.5F)] |
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[InlineData(1F, 1F, 1F, 1F)] |
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public void Convert_Rgb_To_Y_BT709(float r, float g, float b, float y) |
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{ |
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ColorConversionOptions options = new() |
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{ |
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YCoefficients = KnownYCoefficients.BT709 |
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}; |
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Convert_Rgb_To_Y_Core(r, g, b, y, options); |
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} |
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[Theory] |
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[InlineData(0F, 0F, 0F, 0F)] |
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[InlineData(0.5F, 0.5F, 0.5F, 0.49999997F)] |
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[InlineData(1F, 1F, 1F, 0.99999994F)] |
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public void Convert_Rgb_To_Y_BT2020(float r, float g, float b, float y) |
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{ |
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ColorConversionOptions options = new() |
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{ |
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YCoefficients = KnownYCoefficients.BT2020 |
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}; |
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Convert_Rgb_To_Y_Core(r, g, b, y, options); |
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} |
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private static void Convert_Rgb_To_Y_Core(float r, float g, float b, float y, ColorConversionOptions options) |
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{ |
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// Arrange
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Rgb input = new(r, g, b); |
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Y expected = new(y); |
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ColorProfileConverter converter = new(options); |
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Span<Rgb> inputSpan = new Rgb[5]; |
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inputSpan.Fill(input); |
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Span<Y> actualSpan = new Y[5]; |
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// Act
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Y actual = converter.Convert<Rgb, Y>(input); |
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converter.Convert<Rgb, Y>(inputSpan, actualSpan); |
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// Assert
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Assert.Equal(expected, actual, Comparer); |
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for (int i = 0; i < actualSpan.Length; i++) |
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{ |
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Assert.Equal(expected, actualSpan[i], Comparer); |
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} |
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} |
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} |
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@ -0,0 +1,42 @@ |
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using SixLabors.ImageSharp.ColorProfiles; |
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namespace SixLabors.ImageSharp.Tests.ColorProfiles; |
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/// <summary>
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/// Tests the <see cref="Y"/> struct.
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/// </summary>
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[Trait("Color", "Conversion")] |
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public class YTests |
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{ |
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[Fact] |
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public void YConstructorAssignsFields() |
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{ |
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const float y = .75F; |
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Y yValue = new(y); |
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Assert.Equal(y, yValue.L); |
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} |
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[Fact] |
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public void YEquality() |
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{ |
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Y x = default; |
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Y y = new(1F); |
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Assert.True(default == default(Y)); |
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Assert.False(default != default(Y)); |
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Assert.Equal(default, default(Y)); |
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Assert.Equal(new Y(1), new Y(1)); |
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Assert.Equal(new Y(.5F), new Y(.5F)); |
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Assert.False(x.Equals(y)); |
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Assert.False(x.Equals((object)y)); |
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Assert.False(x.GetHashCode().Equals(y.GetHashCode())); |
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} |
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} |
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