Merge pull request #1555 from Franz1960/max-chroma-binarization

New overloads for binary threshold operations. The new argument Color…

.gitattributes

@@ -2,9 +2,13 @@
 # Set default behavior to:
 #   treat as text and
 #   normalize to Unix-style line endings
+###############################################################################
 *           text        eol=lf
-
+###############################################################################
 # Set explicit file behavior to:
+#   treat as text and
+#   normalize to Unix-style line endings
+###############################################################################
 *.asm               text        eol=lf
 *.c                 text        eol=lf
 *.clj               text        eol=lf
@@ -49,19 +53,35 @@
 *.txt               text        eol=lf
 *.vb                text        eol=lf
 *.yml               text        eol=lf
+###############################################################################
+# Set explicit file behavior to:
 #   treat as text
 #   normalize to Unix-style line endings and
 #   diff as csharp
+###############################################################################
 *.cs                text        eol=lf          diff=csharp
+###############################################################################
+# Set explicit file behavior to:
+#   treat as text
+#   normalize to Unix-style line endings and
 #   use a union merge when resoling conflicts
+###############################################################################
 *.csproj            text        eol=lf          merge=union
 *.dbproj            text        eol=lf          merge=union
 *.fsproj            text        eol=lf          merge=union
 *.ncrunchproject    text        eol=lf          merge=union
 *.vbproj            text        eol=lf          merge=union
+###############################################################################
+# Set explicit file behavior to:
+#   treat as text
 #   normalize to Windows-style line endings and
+#   use a union merge when resoling conflicts
+###############################################################################
 *.sln               text        eol=crlf        merge=union
+###############################################################################
+# Set explicit file behavior to:
 #   treat as binary
+###############################################################################
 *.basis             binary
 *.bmp               binary
 *.dds               binary
@@ -90,20 +110,15 @@
 *.woff2             binary
 *.xls               binary
 *.xlsx              binary
+###############################################################################
+# Set explicit file behavior to:
 #   diff as plain text
+###############################################################################
 *.doc               diff=astextplain
 *.docx              diff=astextplain
 *.dot               diff=astextplain
 *.pdf               diff=astextplain
 *.pptx              diff=astextplain
 *.rtf               diff=astextplain
 *.svg               diff=astextplain
-*.jpg filter=lfs diff=lfs merge=lfs -text
-*.jpeg filter=lfs diff=lfs merge=lfs -text
-*.bmp filter=lfs diff=lfs merge=lfs -text
-*.gif filter=lfs diff=lfs merge=lfs -text
-*.png filter=lfs diff=lfs merge=lfs -text
-*.tif filter=lfs diff=lfs merge=lfs -text
-*.tiff filter=lfs diff=lfs merge=lfs -text
-*.tga filter=lfs diff=lfs merge=lfs -text
-*.webp filter=lfs diff=lfs merge=lfs -text
+*.jpg,*.jpeg,*.bmp,*.gif,*.png,*.tif,*.tiff,*.tga,*.webp filter=lfs diff=lfs merge=lfs -text

src/ImageSharp/ColorSpaces/YCbCr.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -100,4 +100,4 @@ public bool Equals(YCbCr other)
                 && this.Cr.Equals(other.Cr);
         }
     }
-}
+}

src/ImageSharp/Processing/BinaryThresholdColorComponent.cs

@@ -0,0 +1,26 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Processing
+{
+    /// <summary>
+    /// The color component to be compared to threshold.
+    /// </summary>
+    public enum BinaryThresholdColorComponent : int
+    {
+        /// <summary>
+        /// Luminance color component according to ITU-R Recommendation BT.709.
+        /// </summary>
+        Luminance = 0,
+
+        /// <summary>
+        /// HSL saturation color component.
+        /// </summary>
+        Saturation = 1,
+
+        /// <summary>
+        /// Maximum of YCbCr chroma value, i.e. Cb and Cr distance from achromatic value.
+        /// </summary>
+        MaxChroma = 2,
+    }
+}

src/ImageSharp/Processing/Extensions/Binarization/BinaryThresholdExtensions.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using SixLabors.ImageSharp.Processing.Processors.Binarization;
@@ -11,29 +11,77 @@ namespace SixLabors.ImageSharp.Processing
     /// </summary>
     public static class BinaryThresholdExtensions
     {
+        /// <summary>
+        /// Applies binarization to the image splitting the pixels at the given threshold with
+        /// Luminance as the color component to be compared to threshold.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="threshold">The threshold to apply binarization of the image. Must be between 0 and 1.</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext BinaryThreshold(this IImageProcessingContext source, float threshold)
+            => source.ApplyProcessor(new BinaryThresholdProcessor(threshold, BinaryThresholdColorComponent.Luminance));
+
         /// <summary>
         /// Applies binarization to the image splitting the pixels at the given threshold.
         /// </summary>
         /// <param name="source">The image this method extends.</param>
         /// <param name="threshold">The threshold to apply binarization of the image. Must be between 0 and 1.</param>
+        /// <param name="colorComponent">The color component to be compared to threshold.</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext BinaryThreshold(
+            this IImageProcessingContext source,
+            float threshold,
+            BinaryThresholdColorComponent colorComponent)
+            => source.ApplyProcessor(new BinaryThresholdProcessor(threshold, colorComponent));
+
+        /// <summary>
+        /// Applies binarization to the image splitting the pixels at the given threshold with
+        /// Luminance as the color component to be compared to threshold.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="threshold">The threshold to apply binarization of the image. Must be between 0 and 1.</param>
+        /// <param name="rectangle">
+        /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
+        /// </param>
         /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
-        public static IImageProcessingContext BinaryThreshold(this IImageProcessingContext source, float threshold) =>
-            source.ApplyProcessor(new BinaryThresholdProcessor(threshold));
+        public static IImageProcessingContext BinaryThreshold(
+            this IImageProcessingContext source,
+            float threshold,
+            Rectangle rectangle)
+            => source.ApplyProcessor(new BinaryThresholdProcessor(threshold, BinaryThresholdColorComponent.Luminance), rectangle);
 
         /// <summary>
         /// Applies binarization to the image splitting the pixels at the given threshold.
         /// </summary>
         /// <param name="source">The image this method extends.</param>
         /// <param name="threshold">The threshold to apply binarization of the image. Must be between 0 and 1.</param>
+        /// <param name="colorComponent">The color component to be compared to threshold.</param>
         /// <param name="rectangle">
         /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
         /// </param>
         /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
         public static IImageProcessingContext BinaryThreshold(
             this IImageProcessingContext source,
             float threshold,
-            Rectangle rectangle) =>
-            source.ApplyProcessor(new BinaryThresholdProcessor(threshold), rectangle);
+            BinaryThresholdColorComponent colorComponent,
+            Rectangle rectangle)
+            => source.ApplyProcessor(new BinaryThresholdProcessor(threshold, colorComponent), rectangle);
+
+        /// <summary>
+        /// Applies binarization to the image splitting the pixels at the given threshold with
+        /// Luminance as the color component to be compared to threshold.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="threshold">The threshold to apply binarization of the image. Must be between 0 and 1.</param>
+        /// <param name="upperColor">The color to use for pixels that are above the threshold.</param>
+        /// <param name="lowerColor">The color to use for pixels that are below the threshold</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext BinaryThreshold(
+            this IImageProcessingContext source,
+            float threshold,
+            Color upperColor,
+            Color lowerColor)
+            => source.ApplyProcessor(new BinaryThresholdProcessor(threshold, upperColor, lowerColor, BinaryThresholdColorComponent.Luminance));
 
         /// <summary>
         /// Applies binarization to the image splitting the pixels at the given threshold.
@@ -42,13 +90,35 @@ public static IImageProcessingContext BinaryThreshold(
         /// <param name="threshold">The threshold to apply binarization of the image. Must be between 0 and 1.</param>
         /// <param name="upperColor">The color to use for pixels that are above the threshold.</param>
         /// <param name="lowerColor">The color to use for pixels that are below the threshold</param>
+        /// <param name="colorComponent">The color component to be compared to threshold.</param>
         /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
         public static IImageProcessingContext BinaryThreshold(
             this IImageProcessingContext source,
             float threshold,
             Color upperColor,
-            Color lowerColor) =>
-            source.ApplyProcessor(new BinaryThresholdProcessor(threshold, upperColor, lowerColor));
+            Color lowerColor,
+            BinaryThresholdColorComponent colorComponent)
+            => source.ApplyProcessor(new BinaryThresholdProcessor(threshold, upperColor, lowerColor, colorComponent));
+
+        /// <summary>
+        /// Applies binarization to the image splitting the pixels at the given threshold with
+        /// Luminance as the color component to be compared to threshold.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="threshold">The threshold to apply binarization of the image. Must be between 0 and 1.</param>
+        /// <param name="upperColor">The color to use for pixels that are above the threshold.</param>
+        /// <param name="lowerColor">The color to use for pixels that are below the threshold</param>
+        /// <param name="rectangle">
+        /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
+        /// </param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext BinaryThreshold(
+            this IImageProcessingContext source,
+            float threshold,
+            Color upperColor,
+            Color lowerColor,
+            Rectangle rectangle)
+            => source.ApplyProcessor(new BinaryThresholdProcessor(threshold, upperColor, lowerColor, BinaryThresholdColorComponent.Luminance), rectangle);
 
         /// <summary>
         /// Applies binarization to the image splitting the pixels at the given threshold.
@@ -57,6 +127,7 @@ public static IImageProcessingContext BinaryThreshold(
         /// <param name="threshold">The threshold to apply binarization of the image. Must be between 0 and 1.</param>
         /// <param name="upperColor">The color to use for pixels that are above the threshold.</param>
         /// <param name="lowerColor">The color to use for pixels that are below the threshold</param>
+        /// <param name="colorComponent">The color component to be compared to threshold.</param>
         /// <param name="rectangle">
         /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
         /// </param>
@@ -66,7 +137,8 @@ public static IImageProcessingContext BinaryThreshold(
             float threshold,
             Color upperColor,
             Color lowerColor,
+            BinaryThresholdColorComponent colorComponent,
             Rectangle rectangle) =>
-            source.ApplyProcessor(new BinaryThresholdProcessor(threshold, upperColor, lowerColor), rectangle);
+            source.ApplyProcessor(new BinaryThresholdProcessor(threshold, upperColor, lowerColor, colorComponent), rectangle);
     }
-}
+}

src/ImageSharp/Processing/Processors/Binarization/BinaryThresholdProcessor.cs

@@ -14,8 +14,19 @@ public class BinaryThresholdProcessor : IImageProcessor
         /// Initializes a new instance of the <see cref="BinaryThresholdProcessor"/> class.
         /// </summary>
         /// <param name="threshold">The threshold to split the image. Must be between 0 and 1.</param>
+        /// <param name="colorComponent">The color component to be compared to threshold.</param>
+        public BinaryThresholdProcessor(float threshold, BinaryThresholdColorComponent colorComponent)
+            : this(threshold, Color.White, Color.Black, colorComponent)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BinaryThresholdProcessor"/> class with
+        /// Luminance as color component to be compared to threshold.
+        /// </summary>
+        /// <param name="threshold">The threshold to split the image. Must be between 0 and 1.</param>
         public BinaryThresholdProcessor(float threshold)
-            : this(threshold, Color.White, Color.Black)
+            : this(threshold, Color.White, Color.Black, BinaryThresholdColorComponent.Luminance)
         {
         }
 
@@ -25,12 +36,26 @@ public BinaryThresholdProcessor(float threshold)
         /// <param name="threshold">The threshold to split the image. Must be between 0 and 1.</param>
         /// <param name="upperColor">The color to use for pixels that are above the threshold.</param>
         /// <param name="lowerColor">The color to use for pixels that are below the threshold.</param>
-        public BinaryThresholdProcessor(float threshold, Color upperColor, Color lowerColor)
+        /// <param name="colorComponent">The color component to be compared to threshold.</param>
+        public BinaryThresholdProcessor(float threshold, Color upperColor, Color lowerColor, BinaryThresholdColorComponent colorComponent)
         {
             Guard.MustBeBetweenOrEqualTo(threshold, 0, 1, nameof(threshold));
             this.Threshold = threshold;
             this.UpperColor = upperColor;
             this.LowerColor = lowerColor;
+            this.ColorComponent = colorComponent;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BinaryThresholdProcessor"/> class with
+        /// Luminance as color component to be compared to threshold.
+        /// </summary>
+        /// <param name="threshold">The threshold to split the image. Must be between 0 and 1.</param>
+        /// <param name="upperColor">The color to use for pixels that are above the threshold.</param>
+        /// <param name="lowerColor">The color to use for pixels that are below the threshold.</param>
+        public BinaryThresholdProcessor(float threshold, Color upperColor, Color lowerColor)
+            : this(threshold, upperColor, lowerColor, BinaryThresholdColorComponent.Luminance)
+        {
         }
 
         /// <summary>
@@ -48,7 +73,12 @@ public BinaryThresholdProcessor(float threshold, Color upperColor, Color lowerCo
         /// </summary>
         public Color LowerColor { get; }
 
-        /// <inheritdoc />
+         /// <summary>
+        /// Gets a value indicating whether to use saturation value instead of luminance.
+        /// </summary>
+        public BinaryThresholdColorComponent ColorComponent { get; }
+
+       /// <inheritdoc />
         public IImageProcessor<TPixel> CreatePixelSpecificProcessor<TPixel>(Configuration configuration, Image<TPixel> source, Rectangle sourceRectangle)
             where TPixel : unmanaged, IPixel<TPixel>
             => new BinaryThresholdProcessor<TPixel>(configuration, this, source, sourceRectangle);