Faster Pow functions

src/ImageSharp/ColorSpaces/Conversion/Implementation/CieLabToCieXyzConverter.cs

@@ -24,11 +24,11 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation
             float fx = (a / 500F) + fy;
             float fz = fy - (b / 200F);
 
-            float fx3 = MathF.Pow(fx, 3F);
+            float fx3 = ImageMaths.Pow3(fx);
-            float fz3 = MathF.Pow(fz, 3F);
+            float fz3 = ImageMaths.Pow3(fz);
 
             float xr = fx3 > CieConstants.Epsilon ? fx3 : ((116F * fx) - 16F) / CieConstants.Kappa;
-            float yr = l > CieConstants.Kappa * CieConstants.Epsilon ? MathF.Pow((l + 16F) / 116F, 3F) : l / CieConstants.Kappa;
+            float yr = l > CieConstants.Kappa * CieConstants.Epsilon ? ImageMaths.Pow3((l + 16F) / 116F) : l / CieConstants.Kappa;
             float zr = fz3 > CieConstants.Epsilon ? fz3 : ((116F * fz) - 16F) / CieConstants.Kappa;
 
             var wxyz = new Vector3(input.WhitePoint.X, input.WhitePoint.Y, input.WhitePoint.Z);

src/ImageSharp/ColorSpaces/Conversion/Implementation/CieLuvToCieXyzConverter.cs

@@ -24,7 +24,7 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation
             float v0 = ComputeV0(input.WhitePoint);
 
             float y = l > CieConstants.Kappa * CieConstants.Epsilon
-                        ? MathF.Pow((l + 16) / 116, 3)
+                        ? ImageMaths.Pow3((l + 16) / 116)
                         : l / CieConstants.Kappa;
 
             float a = ((52 * l / (u + (13 * l * u0))) - 1) / 3;

src/ImageSharp/ColorSpaces/Conversion/Implementation/HunterLabToCieXyzConverter.cs

@@ -24,7 +24,7 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation
             float ka = ComputeKa(input.WhitePoint);
             float kb = ComputeKb(input.WhitePoint);
 
-            float y = MathF.Pow(l / 100F, 2) * yn;
+            float y = ImageMaths.Pow2(l / 100F) * yn;
             float x = (((a / ka) * MathF.Sqrt(y / yn)) + (y / yn)) * xn;
             float z = (((b / kb) * MathF.Sqrt(y / yn)) - (y / yn)) * (-zn);
 

src/ImageSharp/ColorSpaces/Conversion/Implementation/LCompanding.cs

@@ -20,7 +20,7 @@ namespace SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public float Expand(float channel)
         {
-            return channel <= 0.08 ? 100 * channel / CieConstants.Kappa : MathF.Pow((channel + 0.16F) / 1.16F, 3);
+            return channel <= 0.08 ? 100 * channel / CieConstants.Kappa : ImageMaths.Pow3((channel + 0.16F) / 1.16F);
         }
 
         /// <inheritdoc/>

src/ImageSharp/Common/Helpers/ImageMaths.cs

@@ -29,6 +29,22 @@ namespace SixLabors.ImageSharp
             return (x ^ y) - y;
         }
 
+        /// <summary>
+        /// Returns a specified number raised to the power of 2
+        /// </summary>
+        /// <param name="x">A single-precision floating-point number</param>
+        /// <returns>The number <paramref name="x" /> raised to the power of 2.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static float Pow2(float x) => x * x;
+
+        /// <summary>
+        /// Returns a specified number raised to the power of 3
+        /// </summary>
+        /// <param name="x">A single-precision floating-point number</param>
+        /// <returns>The number <paramref name="x" /> raised to the power of 3.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static float Pow3(float x) => x * x * x;
+
         /// <summary>
         /// Returns how many bits are required to store the specified number of colors.
         /// Performs a Log2() on the value.
@@ -38,10 +54,7 @@ namespace SixLabors.ImageSharp
         /// The <see cref="int"/>
         /// </returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static int GetBitsNeededForColorDepth(int colors)
+        public static int GetBitsNeededForColorDepth(int colors) => (int)Math.Ceiling(Math.Log(colors, 2));
-        {
-            return (int)Math.Ceiling(Math.Log(colors, 2));
-        }
 
         /// <summary>
         /// Implementation of 1D Gaussian G(x) function
@@ -56,7 +69,7 @@ namespace SixLabors.ImageSharp
             float denominator = MathF.Sqrt(2 * MathF.PI) * sigma;
 
             float exponentNumerator = -x * x;
-            float exponentDenominator = (float)(2 * Math.Pow(sigma, 2));
+            float exponentDenominator = 2 * Pow2(sigma);
 
             float left = Numerator / denominator;
             float right = MathF.Exp(exponentNumerator / exponentDenominator);
@@ -98,14 +111,12 @@ namespace SixLabors.ImageSharp
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static float GetBcValue(float x, float b, float c)
         {
-            float temp;
-
             if (x < 0F)
             {
                 x = -x;
             }
 
-            temp = x * x;
+            float temp = x * x;
             if (x < 1F)
             {
                 x = ((12 - (9 * b) - (6 * c)) * (x * temp)) + ((-18 + (12 * b) + (6 * c)) * temp) + (6 - (2 * b));
@@ -134,10 +145,7 @@ namespace SixLabors.ImageSharp
         /// The bounding <see cref="Rectangle"/>.
         /// </returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static Rectangle GetBoundingRectangle(Point topLeft, Point bottomRight)
+        public static Rectangle GetBoundingRectangle(Point topLeft, Point bottomRight) => new Rectangle(topLeft.X, topLeft.Y, bottomRight.X - topLeft.X, bottomRight.Y - topLeft.Y);
-        {
-            return new Rectangle(topLeft.X, topLeft.Y, bottomRight.X - topLeft.X, bottomRight.Y - topLeft.Y);
-        }
 
         /// <summary>
         /// Finds the bounding rectangle based on the first instance of any color component other

tests/ImageSharp.Benchmarks/ImageSharp.Benchmarks.csproj

@@ -18,7 +18,7 @@
     <PackageReference Include="Colourful" Version="1.2.1" />
     <PackageReference Include="System.Numerics.Vectors" Version="4.4.0" />
     <PackageReference Include="BenchmarkDotNet" Version="0.10.12" />
-    <PackageReference Include="Colourful" Version="1.1.2" />
+    <PackageReference Include="Colourful" Version="1.2.1" />
     <PackageReference Include="System.Drawing.Common" Version="4.5.0-preview2-26202-05" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)'=='net461'">

tests/ImageSharp.Tests/Colorspaces/ColorSpaceEqualityTests.cs

@@ -9,6 +9,7 @@ using SixLabors.ImageSharp.ColorSpaces;
 using Xunit;
 
 // ReSharper disable InconsistentNaming
+// TODO: This needs to be refactored so that it uses a serializable type once the colorspace code is public
 namespace SixLabors.ImageSharp.Tests.Colorspaces
 {
     /// <summary>
@@ -33,7 +34,7 @@ namespace SixLabors.ImageSharp.Tests.Colorspaces
                     {nameof( YCbCr), YCbCr.Empty }
                 };
 
-        public static readonly IEnumerable<object[]> EmptyData = EmptyDataLookup.Select(x => new [] { x.Key });
+        public static readonly IEnumerable<object[]> EmptyData = EmptyDataLookup.Select(x => new[] { x.Key });
 
         public static readonly TheoryData<object, object, Type> EqualityData =
            new TheoryData<object, object, Type>

tests/ImageSharp.Tests/Helpers/ImageMathsTests.cs

@@ -0,0 +1,39 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+
+namespace SixLabors.ImageSharp.Tests.Helpers
+{
+    using Xunit;
+
+    public class ImageMathsTests
+    {
+        [Fact]
+        public void FasAbsResultMatchesMath()
+        {
+            const int X = -33;
+            int expected = Math.Abs(X);
+
+            Assert.Equal(expected, ImageMaths.FastAbs(X));
+        }
+
+        [Fact]
+        public void Pow2ResultMatchesMath()
+        {
+            const float X = -33;
+            float expected = MathF.Pow(X, 2);
+
+            Assert.Equal(expected, ImageMaths.Pow2(X));
+        }
+
+        [Fact]
+        public void Pow3ResultMatchesMath()
+        {
+            const float X = -33;
+            float expected = MathF.Pow(X, 3);
+
+            Assert.Equal(expected, ImageMaths.Pow3(X));
+        }
+    }
+}

tests/ImageSharp.Tests/TestUtilities/ApproximateFloatComparer.cs

@@ -5,7 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Numerics;
 using SixLabors.ImageSharp.ColorSpaces;
-using SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation.RgbColorSapce;
+using SixLabors.ImageSharp.ColorSpaces.Conversion.Implementation;
 
 namespace SixLabors.ImageSharp.Tests
 {