From 649034b023b685d084800b057715287d0eab8581 Mon Sep 17 00:00:00 2001 From: winscripter <142818255+winscripter@users.noreply.github.com> Date: Mon, 7 Sep 2026 00:50:51 +0400 Subject: [PATCH] Add PQ transfer function --- ...ceptualQuantizationTransferFunctionBase.cs | 54 ------- .../JxlPqTransferFunction.cs | 142 ++++++++++++++++++ 2 files changed, 142 insertions(+), 54 deletions(-) delete mode 100644 src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPerceptualQuantizationTransferFunctionBase.cs create mode 100644 src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPqTransferFunction.cs diff --git a/src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPerceptualQuantizationTransferFunctionBase.cs b/src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPerceptualQuantizationTransferFunctionBase.cs deleted file mode 100644 index eea7b06560..0000000000 --- a/src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPerceptualQuantizationTransferFunctionBase.cs +++ /dev/null @@ -1,54 +0,0 @@ -// Copyright (c) Six Labors. -// Licensed under the Six Labors Split License. - -namespace SixLabors.ImageSharp.Formats.Jxl.Cms.TransferFunctions; - -/// -/// Base class for PQ transfer function. -/// -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); - } -} diff --git a/src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPqTransferFunction.cs b/src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPqTransferFunction.cs new file mode 100644 index 0000000000..654d05429b --- /dev/null +++ b/src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlPqTransferFunction.cs @@ -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; + +/// +/// Perceptual Quantization transfer function. +/// +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 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 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 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 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 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 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 DisplayFromEncoded(Vector x) + { + Vector sign = Vector.Create(0x80000000u).As(); + Vector originalSign = x & sign; + x = Vector.AndNot(sign, x); + + Vector xpxx = (x * x) + x; + Vector magnitude = EvaluateRationalPolynomial(xpxx, DisplayP, DisplayQ); + + return Vector.AndNot(sign, magnitude * Vector.Create(this.scaleFactorFrom10000Nits)) | originalSign; + } + + public Vector EncodedFromDisplay(Vector x) + { + Vector sign = Vector.Create(0x80000000u).As(); + Vector originalSign = x & sign; + x = Vector.AndNot(sign, x); + + + Vector xto025 = Vector.SquareRoot(Vector.SquareRoot(x * Vector.Create(this.scaleFactorTo10000Nits))); + + Vector magnitude = Vector.ConditionalSelect( + Vector.LessThan(x, Vector.Create(1e-4f)), + EvaluateRationalPolynomial(xto025, EncodedPLo, EncodedQLo), + EvaluateRationalPolynomial(xto025, EncodedP, EncodedQ)); + + return Vector.AndNot(sign, magnitude) | originalSign; + } +}