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@ -12,7 +12,8 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison |
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public class TolerantImageComparer : ImageComparer |
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{ |
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// 1% of all pixels in a 100*100 pixel area are allowed to have a difference of 1 unit
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public const float DefaultImageThreshold = 1.0f / (100 * 100 * 255); |
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// 257 = (1 / 255) * 65535.
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public const float DefaultImageThreshold = 257F / (100 * 100 * 65535); |
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/// <summary>
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/// Individual manhattan pixel difference is only added to total image difference when the individual difference is over 'perPixelManhattanThreshold'.
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@ -28,23 +29,23 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison |
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/// <summary>
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/// The maximal tolerated difference represented by a value between 0.0 and 1.0.
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/// Examples of percentage differences on a single pixel:
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/// 1. PixelA = (255,255,255,0) PixelB =(0,0,0,255) leads to 100% difference on a single pixel
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/// 2. PixelA = (255,255,255,0) PixelB =(255,255,255,255) leads to 25% difference on a single pixel
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/// 3. PixelA = (255,255,255,0) PixelB =(128,128,128,128) leads to 50% difference on a single pixel
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/// 1. PixelA = (65535,65535,65535,0) PixelB =(0,0,0,65535) leads to 100% difference on a single pixel
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/// 2. PixelA = (65535,65535,65535,0) PixelB =(65535,65535,65535,65535) leads to 25% difference on a single pixel
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/// 3. PixelA = (65535,65535,65535,0) PixelB =(128,128,128,128) leads to 50% difference on a single pixel
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///
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/// The total differences is the sum of all pixel differences normalized by image dimensions!
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/// The individual distances are calculated using the Manhattan function:
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/// <see>
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/// <cref>https://en.wikipedia.org/wiki/Taxicab_geometry</cref>
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/// </see>
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/// ImageThresholdInPercents = 1.0/255 means that we allow one byte difference per channel on a 1x1 image
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/// ImageThresholdInPercents = 1.0/(100*100*255) means that we allow only one byte difference per channel on a 100x100 image
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/// ImageThresholdInPercents = 1.0/65535 means that we allow one unit difference per channel on a 1x1 image
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/// ImageThresholdInPercents = 1.0/(100*100*65535) means that we allow only one unit difference per channel on a 100x100 image
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/// </summary>
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public float ImageThreshold { get; } |
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/// <summary>
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/// The threshold of the individual pixels before they acumulate towards the overall difference.
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/// For an individual <see cref="Rgba32"/> pixel pair the value is the Manhattan distance of pixels:
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/// For an individual <see cref="Rgba64"/> pixel pair the value is the Manhattan distance of pixels:
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/// <see>
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/// <cref>https://en.wikipedia.org/wiki/Taxicab_geometry</cref>
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/// </see>
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@ -60,12 +61,12 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison |
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int width = actual.Width; |
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// TODO: Comparing through Rgba32 is not robust enough because of the existance of super high precision pixel types.
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// TODO: Comparing through Rgba64 may not robust enough because of the existance of super high precision pixel types.
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var aBuffer = new Rgba32[width]; |
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var bBuffer = new Rgba32[width]; |
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var aBuffer = new Rgba64[width]; |
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var bBuffer = new Rgba64[width]; |
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float totalDifference = 0.0f; |
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float totalDifference = 0F; |
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var differences = new List<PixelDifference>(); |
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@ -74,8 +75,8 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison |
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Span<TPixelA> aSpan = expected.GetPixelRowSpan(y); |
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Span<TPixelB> bSpan = actual.GetPixelRowSpan(y); |
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PixelOperations<TPixelA>.Instance.ToRgba32(aSpan, aBuffer, width); |
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PixelOperations<TPixelB>.Instance.ToRgba32(bSpan, bBuffer, width); |
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PixelOperations<TPixelA>.Instance.ToRgba64(aSpan, aBuffer, width); |
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PixelOperations<TPixelB>.Instance.ToRgba64(bSpan, bBuffer, width); |
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for (int x = 0; x < width; x++) |
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{ |
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@ -91,8 +92,8 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison |
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} |
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} |
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float normalizedDifference = totalDifference / ((float)actual.Width * (float)actual.Height); |
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normalizedDifference /= 4.0f * 255.0f; |
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float normalizedDifference = totalDifference / (actual.Width * (float)actual.Height); |
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normalizedDifference /= 4F * 65535F; |
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if (normalizedDifference > this.ImageThreshold) |
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{ |
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@ -105,12 +106,12 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison |
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} |
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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private static int GetManhattanDistanceInRgbaSpace(ref Rgba32 a, ref Rgba32 b) |
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private static int GetManhattanDistanceInRgbaSpace(ref Rgba64 a, ref Rgba64 b) |
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{ |
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return Diff(a.R, b.R) + Diff(a.G, b.G) + Diff(a.B, b.B) + Diff(a.A, b.A); |
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} |
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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private static int Diff(byte a, byte b) => Math.Abs(a - b); |
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private static int Diff(ushort a, ushort b) => Math.Abs(a - b); |
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} |
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} |
James Jackson-South
8 years ago