Revert "Color is now linear by default."

This reverts commit c4114b2ef1 [formerly 144be0509d7ce2e2702b13b1ea60f708083e4912] [formerly 549f0ac778eb8b1a12d7b7e38280f360aa71ad59] [formerly 3869ebe4d426df2fba1e2996c2fed464a0a55357].


Former-commit-id: a6e0888c25d48a7982a297bfda0ecbc90e20a3d0
Former-commit-id: e404d156c276660e88d0524cce840205c0bb7214
Former-commit-id: ea32434d8dc919a710f521f358ad939a98ada9fe

src/ImageProcessor/Colors/Color.cs

@@ -11,7 +11,7 @@ namespace ImageProcessor
 
     /// <summary>
     /// Represents a four-component color using red, green, blue, and alpha data. 
-    /// Each component is stored in a linear premultiplied format multiplied by the alpha component.
+    /// Each component is stored in premultiplied format multiplied by the alpha component.
     /// </summary>
     /// <remarks>
     /// This struct is fully mutable. This is done (against the guidelines) for the sake of performance,

src/ImageProcessor/Colors/ColorDefinitions.cs

@@ -7,7 +7,7 @@ namespace ImageProcessor
 {
     /// <summary>
     /// Represents a four-component color using red, green, blue, and alpha data. 
-    /// Each component is stored in a linear premultiplied format multiplied by the alpha component.
+    /// Each component is stored in premultiplied format multiplied by the alpha component.
     /// </summary>
     /// <remarks>
     /// This struct is fully mutable. This is done (against the guidelines) for the sake of performance,

src/ImageProcessor/Colors/ColorTransforms.cs

@@ -9,7 +9,7 @@ namespace ImageProcessor
 
     /// <summary>
     /// Represents a four-component color using red, green, blue, and alpha data. 
-    /// Each component is stored in a linear premultiplied format multiplied by the alpha component.
+    /// Each component is stored in premultiplied format multiplied by the alpha component.
     /// </summary>
     /// <remarks>
     /// This struct is fully mutable. This is done (against the guidelines) for the sake of performance,

src/ImageProcessor/Colors/ColorspaceTransforms.cs

@@ -9,7 +9,7 @@ namespace ImageProcessor
 
     /// <summary>
     /// Represents a four-component color using red, green, blue, and alpha data. 
-    /// Each component is stored in a linear premultiplied format multiplied by the alpha component.
+    /// Each component is stored in premultiplied format multiplied by the alpha component.
     /// </summary>
     /// <remarks>
     /// This struct is fully mutable. This is done (against the guidelines) for the sake of performance,
@@ -86,7 +86,7 @@ namespace ImageProcessor
             float g = (x * -0.9689F) + (y * 1.8758F) + (z * 0.0415F);
             float b = (x * 0.0557F) + (y * -0.2040F) + (z * 1.0570F);
 
-            return new Color(r, g, b);
+            return Color.Compress(new Color(r, g, b));
         }
 
         /// <summary>
@@ -226,7 +226,7 @@ namespace ImageProcessor
             float g = (x * -0.9689F) + (y * 1.8758F) + (z * 0.0415F);
             float b = (x * 0.0557F) + (y * -0.2040F) + (z * 1.0570F);
 
-            return new Color(r, g, b);
+            return Color.Compress(new Color(r, g, b));
         }
 
         /// <summary>

src/ImageProcessor/Colors/Colorspaces/CieLab.cs

@@ -79,6 +79,8 @@ namespace ImageProcessor
         public static implicit operator CieLab(Color color)
         {
             // First convert to CIE XYZ
+            color = Color.Expand(color);
+
             float x = (color.R * 0.4124F) + (color.G * 0.3576F) + (color.B * 0.1805F);
             float y = (color.R * 0.2126F) + (color.G * 0.7152F) + (color.B * 0.0722F);
             float z = (color.R * 0.0193F) + (color.G * 0.1192F) + (color.B * 0.9505F);

src/ImageProcessor/Colors/Colorspaces/CieXyz.cs

@@ -79,6 +79,8 @@ namespace ImageProcessor
         /// </returns>
         public static implicit operator CieXyz(Color color)
         {
+            color = Color.Expand(color);
+
             float x = (color.R * 0.4124F) + (color.G * 0.3576F) + (color.B * 0.1805F);
             float y = (color.R * 0.2126F) + (color.G * 0.7152F) + (color.B * 0.0722F);
             float z = (color.R * 0.0193F) + (color.G * 0.1192F) + (color.B * 0.9505F);

src/ImageProcessor/Filters/Brightness.cs

@@ -50,12 +50,12 @@ namespace ImageProcessor.Filters
                         {
                             for (int x = startX; x < endX; x++)
                             {
-                                Color color = source[x, y];
+                                Color color = Color.Expand(source[x, y]);
 
                                 Vector3 vector3 = color.ToVector3();
                                 vector3 += new Vector3(brightness);
 
-                                target[x, y] = new Color(vector3, color.A);
+                                target[x, y] = Color.Compress(new Color(vector3, color.A));
                             }
                         }
                     });

src/ImageProcessor/Filters/ColorMatrix/ColorMatrixFilter.cs

@@ -17,7 +17,7 @@ namespace ImageProcessor.Filters
         public abstract Matrix4x4 Matrix { get; }
 
         /// <inheritdoc/>
-        public virtual bool Compand => false;
+        public virtual bool Compand => true;
 
         /// <inheritdoc/>
         protected override void Apply(ImageBase target, ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle, int startY, int endY)
@@ -57,11 +57,11 @@ namespace ImageProcessor.Filters
 
             if (compand)
             {
-                color = Color.Compress(color);
+                color = Color.Expand(color);
             }
 
             Vector3 transformed = Vector3.Transform(color.ToVector3(), matrix);
-            return compand ? Color.Expand(new Color(transformed, color.A)) : new Color(transformed, color.A);
+            return compand ? Color.Compress(new Color(transformed, color.A)) : new Color(transformed, color.A);
         }
     }
 }

src/ImageProcessor/Filters/ColorMatrix/Hue.cs

@@ -37,7 +37,7 @@
         public override Matrix4x4 Matrix => this.matrix;
 
         /// <inheritdoc/>
-        public override bool Compand => true;
+        public override bool Compand => false;
 
         /// <inheritdoc/>
         protected override void OnApply(ImageBase source, ImageBase target, Rectangle targetRectangle, Rectangle sourceRectangle)

src/ImageProcessor/Filters/ColorMatrix/Sepia.cs

@@ -28,6 +28,6 @@ namespace ImageProcessor.Filters
         };
 
         /// <inheritdoc/>
-        public override bool Compand => true;
+        public override bool Compand => false;
     }
 }

src/ImageProcessor/Filters/Contrast.cs

@@ -51,11 +51,11 @@ namespace ImageProcessor.Filters
                         {
                             for (int x = startX; x < endX; x++)
                             {
-                                Vector4 color = source[x, y].ToVector4();
+                                Vector4 color = Color.Expand(source[x, y]).ToVector4();
                                 color -= shiftVector;
                                 color *= contrastVector;
                                 color += shiftVector;
-                                target[x, y] = new Color(color);
+                                target[x, y] = Color.Compress(new Color(color));
                             }
                         }
                     });

src/ImageProcessor/Formats/Bmp/BmpDecoderCore.cs

@@ -7,7 +7,6 @@ namespace ImageProcessor.Formats
 {
     using System;
     using System.IO;
-    using System.Numerics;
     using System.Threading.Tasks;
 
     /// <summary>
@@ -224,17 +223,11 @@ namespace ImageProcessor.Formats
                                 int arrayOffset = ((row * width) + (colOffset + shift)) * 4;
 
                                 // We divide by 255 as we will store the colors in our floating point format.
-                                // Default colorspace is sRGB TODO: Check if we can detect this.
                                 // Stored in r-> g-> b-> a order.
-                                // Expand from sRGB to linear RGB
-                                Color color =
-                                    Color.Expand(
-                                        new Color(new Vector3(colors[colorIndex + 2], colors[colorIndex + 1], colors[colorIndex]) / 255f));
-
-                                imageData[arrayOffset] = color.R; // r
-                                imageData[arrayOffset + 1] = color.G; // g
-                                imageData[arrayOffset + 2] = color.B; // b
-                                imageData[arrayOffset + 3] = color.A; // a
+                                imageData[arrayOffset] = colors[colorIndex + 2] / 255f; // r
+                                imageData[arrayOffset + 1] = colors[colorIndex + 1] / 255f; // g
+                                imageData[arrayOffset + 2] = colors[colorIndex] / 255f; // b
+                                imageData[arrayOffset + 3] = 1; // a
                             }
                         }
                     });
@@ -277,14 +270,11 @@ namespace ImageProcessor.Formats
 
                             int arrayOffset = ((row * width) + x) * 4;
 
-                            // Expand from sRGB to linear RGB
-                            Color color = Color.Expand(new Color(r, g, b, 1));
-
                             // Stored in r-> g-> b-> a order.
-                            imageData[arrayOffset] = color.R;
-                            imageData[arrayOffset + 1] = color.G;
-                            imageData[arrayOffset + 2] = color.B;
-                            imageData[arrayOffset + 3] = color.A;
+                            imageData[arrayOffset] = r;
+                            imageData[arrayOffset + 1] = g;
+                            imageData[arrayOffset + 2] = b;
+                            imageData[arrayOffset + 3] = 1;
                         }
                     });
         }
@@ -315,15 +305,12 @@ namespace ImageProcessor.Formats
                             int offset = rowOffset + (x * 3);
                             int arrayOffset = ((row * width) + x) * 4;
 
-                            // Expand from sRGB to linear RGB
-                            Color color = Color.Expand(new Color(new Vector3(data[offset + 2], data[offset + 1], data[offset]) / 255f, 1));
-
                             // We divide by 255 as we will store the colors in our floating point format.
                             // Stored in r-> g-> b-> a order.
-                            imageData[arrayOffset] = color.R;
-                            imageData[arrayOffset + 1] = color.G;
-                            imageData[arrayOffset + 2] = color.B;
-                            imageData[arrayOffset + 3] = color.A;
+                            imageData[arrayOffset] = data[offset + 2] / 255f;
+                            imageData[arrayOffset + 1] = data[offset + 1] / 255f;
+                            imageData[arrayOffset + 2] = data[offset] / 255f;
+                            imageData[arrayOffset + 3] = 1;
                         }
                     });
         }
@@ -356,15 +343,10 @@ namespace ImageProcessor.Formats
 
                             // We divide by 255 as we will store the colors in our floating point format.
                             // Stored in r-> g-> b-> a order.
-
-                            // Expand from sRGB to linear RGB
-                            // TODO: Can we use our real alpha here?
-                            Color color = Color.Expand(new Color(new Vector3(data[offset + 2], data[offset + 1], data[offset]) / 255f, 1));
-
-                            imageData[arrayOffset] = color.R;
-                            imageData[arrayOffset + 1] = color.G;
-                            imageData[arrayOffset + 2] = color.B;
-                            imageData[arrayOffset + 3] = color.A;
+                            imageData[arrayOffset] = data[offset + 2] / 255f;
+                            imageData[arrayOffset + 1] = data[offset + 1] / 255f;
+                            imageData[arrayOffset + 2] = data[offset] / 255f;
+                            imageData[arrayOffset + 3] = 1; // TODO: Can we use our real alpha here?
                         }
                     });
         }

src/ImageProcessor/Formats/Bmp/BmpEncoder.cs

@@ -110,13 +110,13 @@ namespace ImageProcessor.Formats
 
                     // Limit the output range and multiply out from our floating point.
                     // Convert back to b-> g-> r-> a order.
-                    // Convert to non-premultiplied sRGB color.
+                    // Convert to non-premultiplied color.
                     float r = data[offset];
                     float g = data[offset + 1];
                     float b = data[offset + 2];
                     float a = data[offset + 3];
 
-                    Bgra32 color = Color.ToNonPremultiplied(Color.Compress(new Color(r, g, b, a)));
+                    Bgra32 color = Color.ToNonPremultiplied(new Color(r, g, b, a));
 
                     writer.Write(color.B);
                     writer.Write(color.G);

src/ImageProcessor/Formats/Jpg/JpegDecoder.cs

@@ -7,7 +7,6 @@ namespace ImageProcessor.Formats
 {
     using System;
     using System.IO;
-    using System.Numerics;
     using System.Threading.Tasks;
 
     using BitMiracle.LibJpeg;
@@ -118,14 +117,10 @@ namespace ImageProcessor.Formats
 
                                 int offset = ((y * pixelWidth) + x) * 4;
 
-                                // Expand from sRGB to linear RGB
-                                Color color =
-                                    Color.Expand(new Color(new Vector3(sample[0], sample[1], sample[2]) / 255f));
-
-                                pixels[offset + 0] = color.R;
-                                pixels[offset + 1] = color.G;
-                                pixels[offset + 2] = color.B;
-                                pixels[offset + 3] = color.A;
+                                pixels[offset + 0] = sample[0] / 255f;
+                                pixels[offset + 1] = sample[1] / 255f;
+                                pixels[offset + 2] = sample[2] / 255f;
+                                pixels[offset + 3] = 1;
                             }
                         });
             }
@@ -144,14 +139,10 @@ namespace ImageProcessor.Formats
 
                             int offset = ((y * pixelWidth) + x) * 4;
 
-                            // Expand from sRGB to linear RGB
-                            Color color =
-                                Color.Expand(new Color(new Vector3(sample[0], sample[0], sample[0]) / 255f));
-
-                            pixels[offset + 0] = color.R;
-                            pixels[offset + 1] = color.G;
-                            pixels[offset + 2] = color.B;
-                            pixels[offset + 3] = color.A;
+                            pixels[offset + 0] = sample[0] / 255f;
+                            pixels[offset + 1] = sample[0] / 255f;
+                            pixels[offset + 2] = sample[0] / 255f;
+                            pixels[offset + 3] = 1;
                         }
                     });
             }

src/ImageProcessor/Formats/Jpg/JpegEncoder.cs

@@ -111,8 +111,7 @@ namespace ImageProcessor.Formats
                             float b = sourcePixels[source + 2];
                             float a = sourcePixels[source + 3];
 
-                            // Compress back to sRGB
-                            Bgra32 color = Color.ToNonPremultiplied(Color.Compress(new Color(r, g, b, a)));
+                            Bgra32 color = Color.ToNonPremultiplied(new Color(r, g, b, a));
 
                             samples[start] = color.R;
                             samples[start + 1] = color.G;

src/ImageProcessor/Samplers/Resampler.cs

@@ -193,11 +193,12 @@ namespace ImageProcessor.Samplers
                                 foreach (Weight xw in horizontalValues)
                                 {
                                     int originX = xw.Index;
-                                    Color sourceColor = source[originX, originY];
+                                    Color sourceColor = Color.Expand(source[originX, originY]);
                                     destination += sourceColor * yw.Value * xw.Value;
                                 }
                             }
 
+                            destination = Color.Compress(destination);
                             target[x, y] = destination;
                         }
                     }
@@ -301,12 +302,13 @@ namespace ImageProcessor.Samplers
 
                                     if (sourceRectangle.Contains(rotated.X, rotated.Y))
                                     {
-                                        Color sourceColor = source[rotated.X, rotated.Y];
+                                        Color sourceColor = Color.Expand(source[rotated.X, rotated.Y]);
                                         destination += sourceColor * yw.Value * xw.Value;
                                     }
                                 }
                             }
 
+                            destination = Color.Compress(destination);
                             target[x, y] = destination;
                         }
                     }