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Merge branch 'master' into sw/wandering-text

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James Jackson-South 7 years ago
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3 changed files with 158 additions and 27 deletions
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  1. 2
      src/ImageSharp/Common/Helpers/ImageMaths.cs
  2. 15
      src/ImageSharp/PixelFormats/PixelImplementations/Gray8.cs
  3. 168
      tests/ImageSharp.Tests/PixelFormats/Gray8Tests.cs

2
src/ImageSharp/Common/Helpers/ImageMaths.cs
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@ -22,7 +22,7 @@ namespace SixLabors.ImageSharp
/// <param name="b">The blue component.</param>
/// <returns>The <see cref="byte"/>.</returns>
[MethodImpl(InliningOptions.ShortMethod)]
public static byte Get8BitBT709Luminance(byte r, byte g, byte b) => (byte)((r * .2126F) + (g * .7152F) + (b * .0722F));
public static byte Get8BitBT709Luminance(byte r, byte g, byte b) => (byte)((r * .2126F) + (g * .7152F) + (b * .0722F) + 0.5f);
/// <summary>
/// Gets the luminance from the rgb components using the formula as specified by ITU-R Recommendation BT.709.

15
src/ImageSharp/PixelFormats/PixelImplementations/Gray8.cs
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@ -18,6 +18,11 @@ namespace SixLabors.ImageSharp.PixelFormats
private static readonly Vector4 Half = new Vector4(0.5F);
private const float Average = 1 / 3F;
private static readonly Vector4 Min = new Vector4(0, 0, 0, 1f);
private static readonly Vector4 Max = Vector4.One;
private static readonly Vector4 Accumulator = new Vector4(255f * Average, 255f * Average, 255f * Average, 0.5f);
/// <summary>
/// Initializes a new instance of the <see cref="Gray8"/> struct.
/// </summary>
@ -64,10 +69,12 @@ namespace SixLabors.ImageSharp.PixelFormats
[MethodImpl(InliningOptions.ShortMethod)]
public void FromVector4(Vector4 vector)
{
vector *= MaxBytes;
vector += Half;
vector = Vector4.Clamp(vector, Vector4.Zero, MaxBytes) * Average;
this.PackedValue = (byte)(vector.X + vector.Y + vector.Z);
vector = Vector4.Max(Min, vector);
vector = Vector4.Min(Max, vector);
float roundedSum = Vector4.Dot(vector, Accumulator);
this.PackedValue = (byte)roundedSum;
}
/// <inheritdoc />

168
tests/ImageSharp.Tests/PixelFormats/Gray8Tests.cs
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@ -1,14 +1,42 @@
// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.
using System.Diagnostics;
using System.Numerics;
using SixLabors.ImageSharp.Common.Helpers;
using SixLabors.ImageSharp.PixelFormats;
using Xunit;
// ReSharper disable InconsistentNaming
namespace SixLabors.ImageSharp.Tests.PixelFormats
{
public class Gray8Tests
{
public static readonly TheoryData<byte> LuminanceData = new TheoryData<byte>()
{
0,
1,
2,
3,
5,
13,
31,
71,
73,
79,
83,
109,
127,
128,
131,
199,
250,
251,
254,
255
};
[Theory]
[InlineData(0)]
[InlineData(255)]
@ -34,9 +62,7 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats
}
[Theory]
[InlineData(0)]
[InlineData(255)]
[InlineData(30)]
[MemberData(nameof(LuminanceData))]
public void Gray8_ToScaledVector4(byte input)
{
// Arrange
@ -53,26 +79,24 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats
Assert.Equal(1, actual.W);
}
[Fact]
public void Gray8_FromVector4()
[Theory]
[MemberData(nameof(LuminanceData))]
public void Gray8_FromVector4(byte luminance)
{
// Arrange
Gray8 gray = default;
const int expected = 128;
var vector = new Gray8(expected).ToVector4();
var vector = new Gray8(luminance).ToVector4();
// Act
gray.FromVector4(vector);
byte actual = gray.PackedValue;
// Assert
Assert.Equal(expected, actual);
Assert.Equal(luminance, actual);
}
[Theory]
[InlineData(0)]
[InlineData(255)]
[InlineData(30)]
[MemberData(nameof(LuminanceData))]
public void Gray8_ToVector4(byte input)
{
// Arrange
@ -89,12 +113,12 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats
Assert.Equal(1, actual.W);
}
[Fact]
public void Gray8_FromRgba32()
[Theory]
[MemberData(nameof(LuminanceData))]
public void Gray8_FromRgba32(byte rgb)
{
// Arrange
Gray8 gray = default;
const byte rgb = 128;
byte expected = ImageMaths.Get8BitBT709Luminance(rgb, rgb, rgb);
// Act
@ -105,24 +129,124 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats
Assert.Equal(expected, actual);
}
[Theory]
[InlineData(0)]
[InlineData(255)]
[InlineData(30)]
public void Gray8_ToRgba32(byte input)
[MemberData(nameof(LuminanceData))]
public void Gray8_ToRgba32(byte luminance)
{
// Arrange
var gray = new Gray8(input);
var gray = new Gray8(luminance);
// Act
Rgba32 actual = default;
gray.ToRgba32(ref actual);
// Assert
Assert.Equal(input, actual.R);
Assert.Equal(input, actual.G);
Assert.Equal(input, actual.B);
Assert.Equal(luminance, actual.R);
Assert.Equal(luminance, actual.G);
Assert.Equal(luminance, actual.B);
Assert.Equal(byte.MaxValue, actual.A);
}
public class Rgba32Compatibility
{
// ReSharper disable once MemberHidesStaticFromOuterClass
public static readonly TheoryData<byte> LuminanceData = Gray8Tests.LuminanceData;
[Theory]
[MemberData(nameof(LuminanceData))]
public void Gray8_FromRgba32_IsInverseOf_ToRgba32(byte luminance)
{
var original = new Gray8(luminance);
Rgba32 rgba = default;
original.ToRgba32(ref rgba);
Gray8 mirror = default;
mirror.FromRgba32(rgba);
Assert.Equal(original, mirror);
}
[Theory]
[MemberData(nameof(LuminanceData))]
public void Rgba32_ToGray8_IsInverseOf_Gray8_ToRgba32(byte luminance)
{
var original = new Gray8(luminance);
Rgba32 rgba = default;
original.ToRgba32(ref rgba);
Gray8 mirror = default;
mirror.FromRgba32(rgba);
Assert.Equal(original, mirror);
}
[Theory]
[MemberData(nameof(LuminanceData))]
public void ToVector4_IsRgba32Compatible(byte luminance)
{
var original = new Gray8(luminance);
Rgba32 rgba = default;
original.ToRgba32(ref rgba);
var gray8Vector = original.ToVector4();
var rgbaVector = original.ToVector4();
Assert.Equal(gray8Vector, rgbaVector, new ApproximateFloatComparer(1e-5f));
}
[Theory]
[MemberData(nameof(LuminanceData))]
public void FromVector4_IsRgba32Compatible(byte luminance)
{
var original = new Gray8(luminance);
Rgba32 rgba = default;
original.ToRgba32(ref rgba);
Vector4 rgbaVector = original.ToVector4();
Gray8 mirror = default;
mirror.FromVector4(rgbaVector);
Assert.Equal(original, mirror);
}
[Theory]
[MemberData(nameof(LuminanceData))]
public void ToScaledVector4_IsRgba32Compatible(byte luminance)
{
var original = new Gray8(luminance);
Rgba32 rgba = default;
original.ToRgba32(ref rgba);
Vector4 gray8Vector = original.ToScaledVector4();
Vector4 rgbaVector = original.ToScaledVector4();
Assert.Equal(gray8Vector, rgbaVector, new ApproximateFloatComparer(1e-5f));
}
[Theory]
[MemberData(nameof(LuminanceData))]
public void FromScaledVector4_IsRgba32Compatible(byte luminance)
{
var original = new Gray8(luminance);
Rgba32 rgba = default;
original.ToRgba32(ref rgba);
Vector4 rgbaVector = original.ToScaledVector4();
Gray8 mirror = default;
mirror.FromScaledVector4(rgbaVector);
Assert.Equal(original, mirror);
}
}
}
}
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