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Add PQ transfer function

pull/3153/head
winscripter 4 weeks ago
parent
412693e488
commit
649034b023
2 changed files with 142 additions and 54 deletions
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  1. 54
      src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPerceptualQuantizationTransferFunctionBase.cs
  2. 142
      src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPqTransferFunction.cs

54
src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPerceptualQuantizationTransferFunctionBase.cs
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@ -1,54 +0,0 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.
namespace SixLabors.ImageSharp.Formats.Jxl.Cms.TransferFunctions;
/// <summary>
/// Base class for PQ transfer function.
/// </summary>
internal abstract class JxlPerceptualQuantizationTransferFunctionBase
{
private const double M1 = 2610.0 / 16384;
private const double M2 = (2523.0 / 4096) * 128;
private const double C1 = 3424.0 / 4096;
private const double C2 = (2413.0 / 4096) * 32;
private const double C3 = (2392.0 / 4096) * 32;
protected static double DisplayFromEncoded(float displayIntensityTarget, double e)
{
if (e == 0.0)
{
return 0.0;
}
double originalSign = e;
e = Math.Abs(e);
double xp = Math.Pow(e, 1.0 / M2);
double num = Math.Max(xp - C1, 0.0);
double den = C2 - (C3 * xp);
double d = Math.Pow(num / den, 1.0 / M1);
return Math.CopySign(d * (10000.0 / displayIntensityTarget), originalSign);
}
protected static double EncodedFromDisplay(float displayIntensityTarget, double d)
{
if (d == 0.0)
{
return 0.0;
}
double originalSign = d;
d = Math.Abs(d);
double xp = Math.Pow(d * (displayIntensityTarget * (1 / 10000)), M1);
double num = C1 + (xp * C2);
double den = 1.0 + (xp * C3);
double e = Math.Pow(num / den, M2);
return Math.CopySign(e, originalSign);
}
}

142
src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPqTransferFunction.cs
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@ -0,0 +1,142 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.
using System.Numerics;
namespace SixLabors.ImageSharp.Formats.Jxl.Cms.TransferFunctions;
/// <summary>
/// Perceptual Quantization transfer function.
/// </summary>
internal struct JxlPqTransferFunction(float displayIntensityTarget = DefaultIntensityTarget)
{
private const double M1 = 2610.0 / 16384;
private const double M2 = (2523.0 / 4096) * 128;
private const double C1 = 3424.0 / 4096;
private const double C2 = (2413.0 / 4096) * 32;
private const double C3 = (2392.0 / 4096) * 32;
private readonly float scaleFactorTo10000Nits = displayIntensityTarget * (1.0f / 10000.0f);
private readonly float scaleFactorFrom10000Nits = 10000.0f / displayIntensityTarget;
private static ReadOnlySpan<float> DisplayP =>
[
2.62975656e-04f, 2.62975656e-04f, 2.62975656e-04f, 2.62975656e-04f,
-6.23553089e-03f, -6.23553089e-03f, -6.23553089e-03f, -6.23553089e-03f,
7.38602301e-01f, 7.38602301e-01f, 7.38602301e-01f, 7.38602301e-01f,
2.64553172e+00f, 2.64553172e+00f, 2.64553172e+00f, 2.64553172e+00f,
5.50034862e-01f, 5.50034862e-01f, 5.50034862e-01f, 5.50034862e-01f
];
private static ReadOnlySpan<float> DisplayQ =>
[
4.21350107e+02f, 4.21350107e+02f, 4.21350107e+02f, 4.21350107e+02f,
-4.28736818e+02f, -4.28736818e+02f, -4.28736818e+02f, -4.28736818e+02f,
1.74364667e+02f, 1.74364667e+02f, 1.74364667e+02f, 1.74364667e+02f,
-3.39078883e+01f, -3.39078883e+01f, -3.39078883e+01f, -3.39078883e+01f,
2.67718770e+00f, 2.67718770e+00f, 2.67718770e+00f, 2.67718770e+00f
];
private static ReadOnlySpan<float> EncodedP =>
[
1.351392e-02f, 1.351392e-02f, 1.351392e-02f, 1.351392e-02f,
-1.095778e+00f, -1.095778e+00f, -1.095778e+00f, -1.095778e+00f,
5.522776e+01f, 5.522776e+01f, 5.522776e+01f, 5.522776e+01f,
1.492516e+02f, 1.492516e+02f, 1.492516e+02f, 1.492516e+02f,
4.838434e+01f, 4.838434e+01f, 4.838434e+01f, 4.838434e+01f
];
private static ReadOnlySpan<float> EncodedQ =>
[
1.012416e+00f, 1.012416e+00f, 1.012416e+00f, 1.012416e+00f,
2.016708e+01f, 2.016708e+01f, 2.016708e+01f, 2.016708e+01f,
9.263710e+01f, 9.263710e+01f, 9.263710e+01f, 9.263710e+01f,
1.120607e+02f, 1.120607e+02f, 1.120607e+02f, 1.120607e+02f,
2.590418e+01f, 2.590418e+01f, 2.590418e+01f, 2.590418e+01f
];
private static ReadOnlySpan<float> EncodedPLo =>
[
9.863406e-06f, 9.863406e-06f, 9.863406e-06f, 9.863406e-06f,
3.881234e-01f, 3.881234e-01f, 3.881234e-01f, 3.881234e-01f,
1.352821e+02f, 1.352821e+02f, 1.352821e+02f, 1.352821e+02f,
6.889862e+04f, 6.889862e+04f, 6.889862e+04f, 6.889862e+04f,
-2.864824e+05f, -2.864824e+05f, -2.864824e+05f, -2.864824e+05f
];
private static ReadOnlySpan<float> EncodedQLo =>
[
3.371868e+01f, 3.371868e+01f, 3.371868e+01f, 3.371868e+01f,
1.477719e+03f, 1.477719e+03f, 1.477719e+03f, 1.477719e+03f,
1.608477e+04f, 1.608477e+04f, 1.608477e+04f, 1.608477e+04f,
-4.389884e+04f, -4.389884e+04f, -4.389884e+04f, -4.389884e+04f,
-2.072546e+05f, -2.072546e+05f, -2.072546e+05f, -2.072546e+05f
];
public static double DisplayFromEncoded(float displayIntensityTarget, double e)
{
if (e == 0.0)
{
return 0.0;
}
double originalSign = e;
e = Math.Abs(e);
double xp = Math.Pow(e, 1.0 / M2);
double num = Math.Max(xp - C1, 0.0);
double den = C2 - (C3 * xp);
double d = Math.Pow(num / den, 1.0 / M1);
return Math.CopySign(d * (10000.0 / displayIntensityTarget), originalSign);
}
public static double EncodedFromDisplay(float displayIntensityTarget, double d)
{
if (d == 0.0)
{
return 0.0;
}
double originalSign = d;
d = Math.Abs(d);
double xp = Math.Pow(d * (displayIntensityTarget * (1 / 10000)), M1);
double num = C1 + (xp * C2);
double den = 1.0 + (xp * C3);
double e = Math.Pow(num / den, M2);
return Math.CopySign(e, originalSign);
}
public Vector<float> DisplayFromEncoded(Vector<float> x)
{
Vector<float> sign = Vector.Create(0x80000000u).As<uint, float>();
Vector<float> originalSign = x & sign;
x = Vector.AndNot(sign, x);
Vector<float> xpxx = (x * x) + x;
Vector<float> magnitude = EvaluateRationalPolynomial(xpxx, DisplayP, DisplayQ);
return Vector.AndNot(sign, magnitude * Vector.Create(this.scaleFactorFrom10000Nits)) | originalSign;
}
public Vector<float> EncodedFromDisplay(Vector<float> x)
{
Vector<float> sign = Vector.Create(0x80000000u).As<uint, float>();
Vector<float> originalSign = x & sign;
x = Vector.AndNot(sign, x);
Vector<float> xto025 = Vector.SquareRoot(Vector.SquareRoot(x * Vector.Create(this.scaleFactorTo10000Nits)));
Vector<float> magnitude = Vector.ConditionalSelect(
Vector.LessThan(x, Vector.Create(1e-4f)),
EvaluateRationalPolynomial(xto025, EncodedPLo, EncodedQLo),
EvaluateRationalPolynomial(xto025, EncodedP, EncodedQ));
return Vector.AndNot(sign, magnitude) | originalSign;
}
}
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