Merge HLG base/derived class into one; abbreviate transfer function class name

src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlHybridLogGammaTransferFunctionBase.cs → src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlHlgTransferFunction.cs

@@ -1,33 +1,78 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.Numerics;
+using SixLabors.ImageSharp.Formats.Jxl.Processing;
+
 namespace SixLabors.ImageSharp.Formats.Jxl.Cms.TransferFunctions;
 
 /// <summary>
-/// Base class for HLG transfer function.
+/// Hybrid Log Gamma transfer function.
 /// </summary>
-internal abstract class JxlHybridLogGammaTransferFunctionBase
+internal sealed class JxlHlgTransferFunction
 {
     // Shared constants used by transfer functions
-    protected const float A = 0.17883277f;
+    private const float A = 0.17883277f;
-    protected const float RA = 1.0f / A;
+    private const float RA = 1.0f / A;
-    protected const float B = 1 - (4 * A);
+    private const float B = 1 - (4 * A);
-    protected const float C = 0.5599107295f;
+    private const float C = 0.5599107295f;
-    protected const float Inverse12 = 1.0f / 12.0f;
+    private const float Inverse12 = 1.0f / 12.0f;
+    private const float HiAdd = B * Inverse12;
+    private const float HiMul = 0.003639807079052639f; // MathF.Exp(-C * RA) * Inverse12
+    private const float HiPow = 8.067285659607931f; // RA * JxlMath.InverseLog2E
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="JxlHlgTransferFunction"/> class.
+    /// </summary>
+    /// <remarks>
+    /// Use static methods. Don't instantiate this class.
+    /// </remarks>
+    private JxlHlgTransferFunction()
+    {
+    }
+
+    public static 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<int> belowInverse12 = Vector.LessThan(x, Vector.Create(Inverse12));
+
+        Vector<float> lo = Vector.SquareRoot(Vector.Create(3.0f) * x);
+        Vector<float> hi = (Vector.Create(A * JxlMath.InverseLog2E) * Vector.Log2((Vector.Create(12f) * x) + Vector.Create(-B))) + Vector.Create(C);
+        Vector<float> magnitude = Vector.ConditionalSelect(belowInverse12, lo, hi);
+        return Vector.AndNot(sign, magnitude) | originalSign;
+    }
+
+    public static 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<int> below05 = Vector.LessThan(x, Vector.Create(0.5f));
+
+        Vector<float> lo = x * (x * Vector.Create(1f / 3f));
+        Vector<float> hi = (Pow2(x * Vector.Create(HiPow)) * Vector.Create(HiMul)) + Vector.Create(HiAdd);
+        Vector<float> magnitude = Vector.ConditionalSelect(below05, lo, hi);
+
+        return Vector.AndNot(sign, magnitude) | originalSign;
+    }
+
+    private static Vector<float> Pow2(Vector<float> x) => JxlSimdUtils.FastPow2f(x);
 
     /// <summary>
     /// Converts encoded signal to display signal.
     /// </summary>
     /// <param name="encoded">The encoded signal</param>
     /// <returns>The display signal</returns>
-    protected static double DisplayFromEncoded(double encoded) => Ootf(InverseOotf(encoded));
+    public static double DisplayFromEncoded(double encoded) => Ootf(InverseOotf(encoded));
 
     /// <summary>
     /// Converts display signal to encoded signal.
     /// </summary>
     /// <param name="display">The display signal</param>
     /// <returns>The encoded signal</returns>
-    protected static double EncodedFromDisplay(double display) => Oetf(InverseOetf(display));
+    public static double EncodedFromDisplay(double display) => Oetf(InverseOetf(display));
 
     /// <summary>
     /// Opto-Electronic Transfer Function - converts
@@ -39,7 +84,7 @@ internal abstract class JxlHybridLogGammaTransferFunctionBase
     /// </remarks>
     /// <param name="s">Scene light</param>
     /// <returns>Digital video signal</returns>
-    private static double Oetf(double s)
+    public static double Oetf(double s)
     {
         if (s == 0)
         {
@@ -70,7 +115,7 @@ internal abstract class JxlHybridLogGammaTransferFunctionBase
     /// </remarks>
     /// <param name="e">Digital video signal</param>
     /// <returns>Scene light</returns>
-    private static double InverseOetf(double e)
+    public static double InverseOetf(double e)
     {
         if (e == 0)
         {
@@ -100,7 +145,7 @@ internal abstract class JxlHybridLogGammaTransferFunctionBase
     /// </remarks>
     /// <param name="s">Input signal</param>
     /// <returns>Digital video signal</returns>
-    private static double Ootf(double s) => s;
+    public static double Ootf(double s) => s;
 
     /// <summary>
     /// Inverse Opto-Optical Transfer Function - as-is.
@@ -110,5 +155,5 @@ internal abstract class JxlHybridLogGammaTransferFunctionBase
     /// </remarks>
     /// <param name="s">Digital video signal</param>
     /// <returns>Scene light</returns>
-    private static double InverseOotf(double s) => s;
+    public static double InverseOotf(double s) => s;
 }

src/ImageSharp/Formats/Jxl/Cms/TransferFunctions/JxlHybridLogGammaTransferFunction.cs

@@ -1,53 +0,0 @@
-// Copyright (c) Six Labors.
-// Licensed under the Six Labors Split License.
-
-using System.Numerics;
-using SixLabors.ImageSharp.Formats.Jxl.Processing;
-
-namespace SixLabors.ImageSharp.Formats.Jxl.Cms.TransferFunctions;
-
-internal sealed class JxlHybridLogGammaTransferFunction : JxlHybridLogGammaTransferFunctionBase
-{
-    private const float HiAdd = B * Inverse12;
-    private const float HiMul = 0.003639807079052639f; // MathF.Exp(-C * RA) * Inverse12
-    private const float HiPow = 8.067285659607931f; // RA * JxlMath.InverseLog2E
-
-    /// <summary>
-    /// Initializes a new instance of the <see cref="JxlHybridLogGammaTransferFunction"/> class.
-    /// </summary>
-    /// <remarks>
-    /// Use static methods. Don't instantiate this class.
-    /// </remarks>
-    private JxlHybridLogGammaTransferFunction()
-    {
-    }
-
-    public static 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<int> belowInverse12 = Vector.LessThan(x, Vector.Create(Inverse12));
-
-        Vector<float> lo = Vector.SquareRoot(Vector.Create(3.0f) * x);
-        Vector<float> hi = (Vector.Create(A * JxlMath.InverseLog2E) * Vector.Log2((Vector.Create(12f) * x) + Vector.Create(-B))) + Vector.Create(C);
-        Vector<float> magnitude = Vector.ConditionalSelect(belowInverse12, lo, hi);
-        return Vector.AndNot(sign, magnitude) | originalSign;
-    }
-
-    public static 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<int> below05 = Vector.LessThan(x, Vector.Create(0.5f));
-
-        Vector<float> lo = x * (x * Vector.Create(1f / 3f));
-        Vector<float> hi = (Pow2(x * Vector.Create(HiPow)) * Vector.Create(HiMul)) + Vector.Create(HiAdd);
-        Vector<float> magnitude = Vector.ConditionalSelect(below05, lo, hi);
-
-        return Vector.AndNot(sign, magnitude) | originalSign;
-    }
-
-    private static Vector<float> Pow2(Vector<float> x) => x * x;
-}