mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
8 years ago
18 changed files with 73 additions and 23 deletions
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// Copyright (c) Six Labors and contributors.
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// Licensed under the Apache License, Version 2.0.
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using SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation; |
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namespace SixLabors.ImageSharp.ColorSpaces |
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namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation |
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{ |
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/// <summary>
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/// Pair of companding functions for <see cref="RgbWorkingSpace"/>.
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// Copyright (c) Six Labors and contributors.
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// Licensed under the Apache License, Version 2.0.
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using SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation; |
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using Xunit; |
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namespace SixLabors.ImageSharp.Tests.Colorspaces.Conversion |
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{ |
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/// <summary>
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/// Tests various companding algorithms. Numbers are hand calculated from formulas online.
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/// TODO: Oddly the formula for converting to/from Rec 2020 and 709 from Wikipedia seems to cause the value to
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/// fail a round trip. They're large spaces so this is a surprise. More reading required!!
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/// </summary>
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public class CompandingTests |
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{ |
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private static readonly ApproximateFloatComparer FloatComparer = new ApproximateFloatComparer(.00001F); |
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[Fact] |
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public void Rec2020CompandingIsCorrect() |
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{ |
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CompandingIsCorrectImpl(new Rec2020Companding(), .667F, .4484759F, .3937096F); |
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} |
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[Fact] |
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public void Rec709CompandingIsCorrect() |
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{ |
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CompandingIsCorrectImpl(new Rec709Companding(), .667F, .4483577F, .3937451F); |
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} |
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[Fact] |
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public void SRgbCompandingIsCorrect() |
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{ |
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CompandingIsCorrectImpl(new SRgbCompanding(), .667F, .40242353F, .667F); |
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} |
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[Fact] |
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public void GammaCompandingIsCorrect() |
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{ |
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CompandingIsCorrectImpl(new GammaCompanding(2.2F), .667F, .41027668F, .667F); |
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} |
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[Fact] |
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public void LCompandingIsCorrect() |
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{ |
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CompandingIsCorrectImpl(new LCompanding(), .667F, .36236193F, .58908917F); |
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} |
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private static void CompandingIsCorrectImpl(ICompanding companding, float input, float expanded, float compressed) |
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{ |
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float e = companding.Expand(input); |
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float c = companding.Compress(e); |
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Assert.Equal(expanded, e, FloatComparer); |
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Assert.Equal(compressed, c, FloatComparer); |
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} |
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} |
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} |
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