Use compand and inverse.

Former-commit-id: 6613974e95dea97465c0252e785cd80b6f1f33bc
Former-commit-id: 17648f2923890ff36fe4fd2f3bc0223835fd4db7
Former-commit-id: 63c6fa184d0e73dade3f06952b84ef33dd86393f

src/ImageProcessor/Colors/Color.cs

@@ -8,6 +8,7 @@ namespace ImageProcessor
     using System;
     using System.ComponentModel;
     using System.Numerics;
+    using System.Runtime.CompilerServices;
 
     /// <summary>
     /// Represents a four-component color using red, green, blue, and alpha data.

src/ImageProcessor/Common/Helpers/PixelOperations.cs

@@ -1,92 +0,0 @@
-// <copyright file="PixelOperations.cs" company="James South">
-// Copyright (c) James South and contributors.
-// Licensed under the Apache License, Version 2.0.
-// </copyright>
-
-namespace ImageProcessor
-{
-    using System;
-    using System.Numerics;
-
-    /// <summary>
-    /// Performs per-pixel operations.
-    /// </summary>
-    public static class PixelOperations
-    {
-        /// <summary>
-        /// Converts an pixel from an sRGB color-space to the equivalent linear color-space.
-        /// </summary>
-        /// <param name="composite">
-        /// The <see cref="Bgra32"/> to convert.
-        /// </param>
-        /// <returns>
-        /// The <see cref="Bgra32"/>.
-        /// </returns>
-        public static Color ToLinear(Color composite)
-        {
-            // TODO: Figure out a way to either cache these values quickly or perform the calcuations together.
-            composite.R = SrgbToLinear(composite.R);
-            composite.G = SrgbToLinear(composite.G);
-            composite.B = SrgbToLinear(composite.B);
-
-            return composite;
-        }
-
-        /// <summary>
-        /// Converts a pixel from a linear color-space to the equivalent sRGB color-space.
-        /// </summary>
-        /// <param name="linear">
-        /// The <see cref="Bgra32"/> to convert.
-        /// </param>
-        /// <returns>
-        /// The <see cref="Bgra32"/>.
-        /// </returns>
-        public static Color ToSrgb(Color linear)
-        {
-            // TODO: Figure out a way to either cache these values quickly or perform the calcuations together.
-            linear.R = LinearToSrgb(linear.R);
-            linear.G = LinearToSrgb(linear.G);
-            linear.B = LinearToSrgb(linear.B);
-
-            return linear;
-        }
-
-        /// <summary>
-        /// Gets the correct linear value from an sRGB signal.
-        /// <see href="http://www.4p8.com/eric.brasseur/gamma.html#formulas"/>
-        /// <see href="http://entropymine.com/imageworsener/srgbformula/"/>
-        /// </summary>
-        /// <param name="signal">The signal value to convert.</param>
-        /// <returns>
-        /// The <see cref="float"/>.
-        /// </returns>
-        private static float SrgbToLinear(float signal)
-        {
-            if (signal <= 0.04045f)
-            {
-                return signal / 12.92f;
-            }
-
-            return (float)Math.Pow((signal + 0.055f) / 1.055f, 2.4f);
-        }
-
-        /// <summary>
-        /// Gets the correct sRGB value from an linear signal.
-        /// <see href="http://www.4p8.com/eric.brasseur/gamma.html#formulas"/>
-        /// <see href="http://entropymine.com/imageworsener/srgbformula/"/>
-        /// </summary>
-        /// <param name="signal">The signal value to convert.</param>
-        /// <returns>
-        /// The <see cref="float"/>.
-        /// </returns>
-        private static float LinearToSrgb(float signal)
-        {
-            if (signal <= 0.0031308f)
-            {
-                return signal * 12.92f;
-            }
-
-            return (1.055f * (float)Math.Pow(signal, 0.41666666f)) - 0.055f;
-        }
-    }
-}

src/ImageProcessor/Filters/Brightness.cs

@@ -66,12 +66,12 @@ namespace ImageProcessor.Filters
         /// </returns>
         private static Color AdjustBrightness(Color color, float brightness)
         {
-            color = PixelOperations.ToLinear(color);
+            color = Color.InverseCompand(color);
 
             Vector3 vector3 = color.ToVector3();
             vector3 += new Vector3(brightness, brightness, brightness);
 
-            return PixelOperations.ToSrgb(new Color(vector3, color.A));
+            return Color.Compand(new Color(vector3, color.A));
         }
     }
 }

src/ImageProcessor/Filters/ColorMatrix/ColorMatrixFilter.cs

@@ -50,7 +50,7 @@ namespace ImageProcessor.Filters
         /// </returns>
         private static Color ApplyMatrix(Color color, Matrix4x4 matrix)
         {
-            color = PixelOperations.ToLinear(color);
+            color = Color.InverseCompand(color);
 
             float sr = color.R;
             float sg = color.G;
@@ -60,7 +60,7 @@ namespace ImageProcessor.Filters
             color.G = (sr * matrix.M12) + (sg * matrix.M22) + (sb * matrix.M32) + matrix.M42;
             color.B = (sr * matrix.M13) + (sg * matrix.M23) + (sb * matrix.M33) + matrix.M43;
 
-            return PixelOperations.ToSrgb(color);
+            return Color.Compand(color);
         }
     }
 }

src/ImageProcessor/Filters/Contrast.cs

@@ -65,7 +65,7 @@ namespace ImageProcessor.Filters
         /// </returns>
         private static Color AdjustContrast(Color color, float contrast)
         {
-            color = PixelOperations.ToLinear(color);
+            color = Color.InverseCompand(color);
 
             // Seems to be faster than Vector3.
             color.R -= 0.5f;
@@ -80,7 +80,7 @@ namespace ImageProcessor.Filters
             color.B *= contrast;
             color.B += 0.5f;
 
-            return PixelOperations.ToSrgb(color);
+            return Color.Compand(color);
         }
     }
 }

src/ImageProcessor/ImageProcessor.csproj

@@ -47,7 +47,6 @@
     <Compile Include="Colors\Color.cs" />
     <Compile Include="Common\Extensions\EnumerableExtensions.cs" />
     <Compile Include="Common\Helpers\ImageMaths.cs" />
-    <Compile Include="Common\Helpers\PixelOperations.cs" />
     <Compile Include="Filters\Blend.cs" />
     <Compile Include="Filters\ColorMatrix\IColorMatrixFilter.cs" />
     <Compile Include="Filters\Convolution\Convolution2PassFilter.cs" />

src/ImageProcessor/Samplers/Resize.cs

@@ -97,8 +97,7 @@ namespace ImageProcessor.Samplers
                                     }
 
                                     int originX = xw.Index;
-                                    Color sourceColor = PixelOperations.ToLinear(source[originX, originY]);
-
+                                    Color sourceColor = Color.InverseCompand(source[originX, originY]);
                                     if (Math.Abs(sourceColor.A) < Epsilon)
                                     {
                                         continue;
@@ -113,8 +112,7 @@ namespace ImageProcessor.Samplers
                                 }
                             }
 
-                            destination = PixelOperations.ToSrgb(destination);
-                            target[x, y] = destination;
+                            target[x, y] = Color.Compand(destination);
                         }
                     }
                 });

src/ImageProcessor/project.lock.json.REMOVED.git-id

@@ -1 +1 @@
-eb00c54ee74016c2b70f81963e7e8f83cb2dd54b
+3f05708641eb3ed085d4689aae4a960eb067fd16