From 04b05fb00e5d9f71b3263f99dc3fce56bdf472b5 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Sun, 8 Nov 2015 13:18:13 +1100
Subject: [PATCH] Refactor edge detection to streamline API

Former-commit-id: 9e5b8edfb049780f3f8a553f02b2fee20b29f91d
Former-commit-id: 66241f9dd5f8be909f03d8b6435e86f69b3f95d4
Former-commit-id: b34b5df5f557b528d9dcea49e92d93532b984cb6
---
 ImageProcessor.sln.DotSettings                |  2 ++
 .../Filters/ColorMatrix/IColorMatrixFilter.cs |  2 +-
 .../Filters/ColorMatrix/Saturation.cs         |  2 +-
 .../Convolution/Convolution2DFilter.cs        |  2 +-
 .../Convolution/Convolution2PassFilter.cs     |  2 +-
 .../Filters/Convolution/ConvolutionFilter.cs  |  8 ++---
 .../EdgeDetection/EdgeDetector2DFilter.cs     | 26 ++++++++++++++
 .../EdgeDetection/EdgeDetectorFilter.cs       | 26 ++++++++++++++
 .../EdgeDetection/IEdgeDetectorFilter.cs      | 19 ++++++++++
 .../Convolution/EdgeDetection/Kayyali.cs      | 10 ++----
 .../Convolution/EdgeDetection/Kirsch.cs       | 10 ++----
 .../Convolution/EdgeDetection/Laplacian3X3.cs |  8 ++---
 .../Convolution/EdgeDetection/Laplacian5X5.cs |  8 ++---
 .../EdgeDetection/LaplacianOfGaussian.cs      | 10 +++---
 .../Convolution/EdgeDetection/Prewitt.cs      | 13 ++++---
 .../Convolution/EdgeDetection/RobertsCross.cs | 10 ++----
 .../Convolution/EdgeDetection/Scharr.cs       | 10 ++----
 .../Convolution/EdgeDetection/Sobel.cs        | 10 ++----
 .../Filters/Convolution/GuassianBlur.cs       |  2 +-
 .../Filters/Convolution/GuassianSharpen.cs    |  2 +-
 .../Filters/ImageFilterExtensions.cs          | 36 +++++++++++++++++++
 .../Formats/Gif/Quantizer/OctreeQuantizer.cs  |  2 --
 src/ImageProcessor/ImageProcessor.csproj      |  3 ++
 src/ImageProcessor/ParallelImageProcessor.cs  |  7 ++--
 src/ImageProcessor/Samplers/Resize.cs         |  2 +-
 .../Processors/Filters/FilterTests.cs         |  2 +-
 26 files changed, 159 insertions(+), 75 deletions(-)
 create mode 100644 ImageProcessor.sln.DotSettings
 create mode 100644 src/ImageProcessor/Filters/Convolution/EdgeDetection/EdgeDetector2DFilter.cs
 create mode 100644 src/ImageProcessor/Filters/Convolution/EdgeDetection/EdgeDetectorFilter.cs
 create mode 100644 src/ImageProcessor/Filters/Convolution/EdgeDetection/IEdgeDetectorFilter.cs

diff --git a/ImageProcessor.sln.DotSettings b/ImageProcessor.sln.DotSettings
new file mode 100644
index 000000000..39e42e16e
--- /dev/null
+++ b/ImageProcessor.sln.DotSettings
@@ -0,0 +1,2 @@
+<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/Abbreviations/=XY/@EntryIndexedValue">XY</s:String></wpf:ResourceDictionary>
\ No newline at end of file
diff --git a/src/ImageProcessor/Filters/ColorMatrix/IColorMatrixFilter.cs b/src/ImageProcessor/Filters/ColorMatrix/IColorMatrixFilter.cs
index fdc0fcafa..b85f2eee9 100644
--- a/src/ImageProcessor/Filters/ColorMatrix/IColorMatrixFilter.cs
+++ b/src/ImageProcessor/Filters/ColorMatrix/IColorMatrixFilter.cs
@@ -11,7 +11,7 @@ namespace ImageProcessor.Filters
     /// Encapsulates properties and methods for creating processors that utilize a matrix to
     /// alter the image pixels.
     /// </summary>
-    public interface IColorMatrixFilter
+    public interface IColorMatrixFilter : IImageProcessor
     {
         /// <summary>
         /// Gets the <see cref="Matrix4x4"/> used to alter the image.
diff --git a/src/ImageProcessor/Filters/ColorMatrix/Saturation.cs b/src/ImageProcessor/Filters/ColorMatrix/Saturation.cs
index 385d7a949..32c4defc6 100644
--- a/src/ImageProcessor/Filters/ColorMatrix/Saturation.cs
+++ b/src/ImageProcessor/Filters/ColorMatrix/Saturation.cs
@@ -40,7 +40,7 @@ namespace ImageProcessor.Filters
         public override Matrix4x4 Matrix => this.matrix;
 
         /// <inheritdoc/>
-        protected override void OnApply(Rectangle targetRectangle, Rectangle sourceRectangle)
+        protected override void OnApply(ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle)
         {
             float saturationFactor = this.saturation / 100f;
 
diff --git a/src/ImageProcessor/Filters/Convolution/Convolution2DFilter.cs b/src/ImageProcessor/Filters/Convolution/Convolution2DFilter.cs
index b9852b804..4fae35f81 100644
--- a/src/ImageProcessor/Filters/Convolution/Convolution2DFilter.cs
+++ b/src/ImageProcessor/Filters/Convolution/Convolution2DFilter.cs
@@ -9,7 +9,7 @@ namespace ImageProcessor.Filters
     using System.Threading.Tasks;
 
     /// <summary>
-    /// Defines a filter that uses a matrix to perform convolution across two dimensions against an image.
+    /// Defines a filter that uses two one-dimensional matrices to perform convolution against an image.
     /// </summary>
     public abstract class Convolution2DFilter : ParallelImageProcessor
     {
diff --git a/src/ImageProcessor/Filters/Convolution/Convolution2PassFilter.cs b/src/ImageProcessor/Filters/Convolution/Convolution2PassFilter.cs
index 6218414cb..cf75520ed 100644
--- a/src/ImageProcessor/Filters/Convolution/Convolution2PassFilter.cs
+++ b/src/ImageProcessor/Filters/Convolution/Convolution2PassFilter.cs
@@ -8,7 +8,7 @@ namespace ImageProcessor.Filters
     using System.Threading.Tasks;
 
     /// <summary>
-    /// Defines a filter that uses a matrix to perform convolution across two dimensions against an image.
+    /// Defines a filter that uses two one-dimensional matrices to perform two-pass convolution against an image.
     /// </summary>
     public abstract class Convolution2PassFilter : ParallelImageProcessor
     {
diff --git a/src/ImageProcessor/Filters/Convolution/ConvolutionFilter.cs b/src/ImageProcessor/Filters/Convolution/ConvolutionFilter.cs
index 9ee763e6a..6d114adab 100644
--- a/src/ImageProcessor/Filters/Convolution/ConvolutionFilter.cs
+++ b/src/ImageProcessor/Filters/Convolution/ConvolutionFilter.cs
@@ -8,19 +8,19 @@ namespace ImageProcessor.Filters
     using System.Threading.Tasks;
 
     /// <summary>
-    /// Defines a filter that uses a matrix to perform convolution across a single dimension against an image.
+    /// Defines a filter that uses a 2 dimensional matrix to perform convolution against an image.
     /// </summary>
     public abstract class ConvolutionFilter : ParallelImageProcessor
     {
         /// <summary>
-        /// Gets the horizontal gradient operator.
+        /// Gets the 2d gradient operator.
         /// </summary>
-        public abstract float[,] KernelX { get; }
+        public abstract float[,] KernelXY { get; }
 
         /// <inheritdoc/>
         protected override void Apply(ImageBase target, ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle, int startY, int endY)
         {
-            float[,] kernelX = this.KernelX;
+            float[,] kernelX = this.KernelXY;
             int kernelLength = kernelX.GetLength(0);
             int radius = kernelLength >> 1;
 
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/EdgeDetector2DFilter.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/EdgeDetector2DFilter.cs
new file mode 100644
index 000000000..94990b839
--- /dev/null
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/EdgeDetector2DFilter.cs
@@ -0,0 +1,26 @@
+// <copyright file="EdgeDetector2DFilter.cs" company="James South">
+// Copyright (c) James South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessor.Filters
+{
+    /// <summary>
+    /// Defines a filter that detects edges within an image using two
+    /// one-dimensional matrices.
+    /// </summary>
+    public abstract class EdgeDetector2DFilter : Convolution2DFilter, IEdgeDetectorFilter
+    {
+        /// <inheritdoc/>
+        public bool Greyscale { get; set; }
+
+        /// <inheritdoc/>
+        protected override void OnApply(ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle)
+        {
+            if (this.Greyscale)
+            {
+                new GreyscaleBt709().Apply(source, source, sourceRectangle);
+            }
+        }
+    }
+}
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/EdgeDetectorFilter.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/EdgeDetectorFilter.cs
new file mode 100644
index 000000000..b2cb1bbb8
--- /dev/null
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/EdgeDetectorFilter.cs
@@ -0,0 +1,26 @@
+// <copyright file="EdgeDetectorFilter.cs" company="James South">
+// Copyright (c) James South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessor.Filters
+{
+    /// <summary>
+    /// Defines a filter that detects edges within an image using a single
+    /// two dimensional matrix.
+    /// </summary>
+    public abstract class EdgeDetectorFilter : ConvolutionFilter, IEdgeDetectorFilter
+    {
+        /// <inheritdoc/>
+        public bool Greyscale { get; set; }
+
+        /// <inheritdoc/>
+        protected override void OnApply(ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle)
+        {
+            if (this.Greyscale)
+            {
+                new GreyscaleBt709().Apply(source, source, sourceRectangle);
+            }
+        }
+    }
+}
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/IEdgeDetectorFilter.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/IEdgeDetectorFilter.cs
new file mode 100644
index 000000000..714dffac2
--- /dev/null
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/IEdgeDetectorFilter.cs
@@ -0,0 +1,19 @@
+// <copyright file="IEdgeDetectorFilter.cs" company="James South">
+// Copyright (c) James South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessor.Filters
+{
+    /// <summary>
+    /// Provides properties and methods allowing the detection of edges within an image.
+    /// </summary>
+    public interface IEdgeDetectorFilter : IImageProcessor
+    {
+        /// <summary>
+        /// Gets or sets a value indicating whether to convert the
+        /// image to greyscale before performing edge detection.
+        /// </summary>
+        bool Greyscale { get; set; }
+    }
+}
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Kayyali.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Kayyali.cs
index f32260883..1f2deb287 100644
--- a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Kayyali.cs
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Kayyali.cs
@@ -9,11 +9,9 @@ namespace ImageProcessor.Filters
     /// The Kayyali operator filter.
     /// <see href="http://edgedetection.webs.com/"/>
     /// </summary>
-    public class Kayyali : Convolution2DFilter
+    public class Kayyali : EdgeDetector2DFilter
     {
-        /// <summary>
-        /// Gets the horizontal gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelX => new float[,]
         {
             { 6, 0, -6 },
@@ -21,9 +19,7 @@ namespace ImageProcessor.Filters
             { -6, 0, 6 }
         };
 
-        /// <summary>
-        /// Gets the vertical gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelY => new float[,]
         {
             { -6, 0, 6 },
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Kirsch.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Kirsch.cs
index e38572bbb..1fac19272 100644
--- a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Kirsch.cs
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Kirsch.cs
@@ -9,11 +9,9 @@ namespace ImageProcessor.Filters
     /// The Kirsch operator filter.
     /// <see href="http://en.wikipedia.org/wiki/Kirsch_operator"/>
     /// </summary>
-    public class Kirsch : Convolution2DFilter
+    public class Kirsch : EdgeDetector2DFilter
     {
-        /// <summary>
-        /// Gets the horizontal gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelX => new float[,]
         {
             { 5, 5, 5 },
@@ -21,9 +19,7 @@ namespace ImageProcessor.Filters
             { -3, -3, -3 }
         };
 
-        /// <summary>
-        /// Gets the vertical gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelY => new float[,]
         {
             { 5, -3, -3 },
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Laplacian3X3.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Laplacian3X3.cs
index e3a170da5..18ea3da19 100644
--- a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Laplacian3X3.cs
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Laplacian3X3.cs
@@ -9,12 +9,10 @@ namespace ImageProcessor.Filters
     /// The Laplacian 3 x 3 operator filter.
     /// <see href="http://en.wikipedia.org/wiki/Discrete_Laplace_operator"/>
     /// </summary>
-    public class Laplacian3X3 : ConvolutionFilter
+    public class Laplacian3X3 : EdgeDetectorFilter
     {
-        /// <summary>
-        /// Gets the horizontal gradient operator.
-        /// </summary>
-        public override float[,] KernelX => new float[,]
+        /// <inheritdoc/>
+        public override float[,] KernelXY => new float[,]
         {
             { -1, -1, -1 },
             { -1,  8, -1 },
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Laplacian5X5.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Laplacian5X5.cs
index 7ee2a93ed..6fc83cd8e 100644
--- a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Laplacian5X5.cs
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Laplacian5X5.cs
@@ -9,12 +9,10 @@ namespace ImageProcessor.Filters
     /// The Laplacian 5 x 5 operator filter.
     /// <see href="http://en.wikipedia.org/wiki/Discrete_Laplace_operator"/>
     /// </summary>
-    public class Laplacian5X5 : ConvolutionFilter
+    public class Laplacian5X5 : EdgeDetectorFilter
     {
-        /// <summary>
-        /// Gets the horizontal gradient operator.
-        /// </summary>
-        public override float[,] KernelX => new float[,]
+        /// <inheritdoc/>
+        public override float[,] KernelXY => new float[,]
         {
             { -1, -1, -1, -1, -1 },
             { -1, -1, -1, -1, -1 },
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/LaplacianOfGaussian.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/LaplacianOfGaussian.cs
index 9a7883ce8..9033ac285 100644
--- a/src/ImageProcessor/Filters/Convolution/EdgeDetection/LaplacianOfGaussian.cs
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/LaplacianOfGaussian.cs
@@ -7,14 +7,12 @@ namespace ImageProcessor.Filters
 {
     /// <summary>
     /// The Laplacian of Gaussian operator filter.
-    /// <see href="http://fourier.eng.hmc.edu/e161/lectures/gradient/node9.html"/>
+    /// <see href="http://fourier.eng.hmc.edu/e161/lectures/gradient/node8.html"/>
     /// </summary>
-    public class LaplacianOfGaussian : ConvolutionFilter
+    public class LaplacianOfGaussian : EdgeDetectorFilter
     {
-        /// <summary>
-        /// Gets the horizontal gradient operator.
-        /// </summary>
-        public override float[,] KernelX => new float[,]
+        /// <inheritdoc/>
+        public override float[,] KernelXY => new float[,]
         {
             { 0, 0, -1,  0,  0 },
             { 0, -1, -2, -1,  0 },
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Prewitt.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Prewitt.cs
index c246ece0d..13415a1c1 100644
--- a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Prewitt.cs
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Prewitt.cs
@@ -9,11 +9,9 @@ namespace ImageProcessor.Filters
     /// The Prewitt operator filter.
     /// <see href="http://en.wikipedia.org/wiki/Prewitt_operator"/>
     /// </summary>
-    public class Prewitt : Convolution2DFilter
+    public class Prewitt : EdgeDetector2DFilter
     {
-        /// <summary>
-        /// Gets the horizontal gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelX => new float[,]
         {
             { -1, 0, 1 },
@@ -21,14 +19,15 @@ namespace ImageProcessor.Filters
             { -1, 0, 1 }
         };
 
-        /// <summary>
-        /// Gets the vertical gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelY => new float[,]
         {
             { 1, 1, 1 },
             { 0, 0, 0 },
             { -1, -1, -1 }
         };
+
+        /// <inheritdoc/>
+        public bool Greyscale { get; set; }
     }
 }
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/RobertsCross.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/RobertsCross.cs
index 9af29b3ec..a8f85cee1 100644
--- a/src/ImageProcessor/Filters/Convolution/EdgeDetection/RobertsCross.cs
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/RobertsCross.cs
@@ -9,20 +9,16 @@ namespace ImageProcessor.Filters
     /// The Roberts Cross operator filter.
     /// <see href="http://en.wikipedia.org/wiki/Roberts_cross"/>
     /// </summary>
-    public class RobertsCross : Convolution2DFilter
+    public class RobertsCross : EdgeDetector2DFilter
     {
-        /// <summary>
-        /// Gets the horizontal gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelX => new float[,]
         {
             { 1, 0 },
             { 0, -1 }
         };
 
-        /// <summary>
-        /// Gets the vertical gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelY => new float[,]
         {
             { 0, 1 },
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Scharr.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Scharr.cs
index 3ec8a8630..523648a64 100644
--- a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Scharr.cs
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Scharr.cs
@@ -9,11 +9,9 @@ namespace ImageProcessor.Filters
     /// The Scharr operator filter.
     /// <see href="http://en.wikipedia.org/wiki/Sobel_operator#Alternative_operators"/>
     /// </summary>
-    public class Scharr : Convolution2DFilter
+    public class Scharr : EdgeDetector2DFilter
     {
-        /// <summary>
-        /// Gets the horizontal gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelX => new float[,]
         {
             { -3, 0, 3 },
@@ -21,9 +19,7 @@ namespace ImageProcessor.Filters
             { -3, 0, 3 }
         };
 
-        /// <summary>
-        /// Gets the vertical gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelY => new float[,]
         {
             { 3, 10, 3 },
diff --git a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Sobel.cs b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Sobel.cs
index a1a450cf3..a9fb820e5 100644
--- a/src/ImageProcessor/Filters/Convolution/EdgeDetection/Sobel.cs
+++ b/src/ImageProcessor/Filters/Convolution/EdgeDetection/Sobel.cs
@@ -9,11 +9,9 @@ namespace ImageProcessor.Filters
     /// The Sobel operator filter.
     /// <see href="http://en.wikipedia.org/wiki/Sobel_operator"/>
     /// </summary>
-    public class Sobel : Convolution2DFilter
+    public class Sobel : EdgeDetector2DFilter
     {
-        /// <summary>
-        /// Gets the horizontal gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelX => new float[,]
         {
             { -1, 0, 1 },
@@ -21,9 +19,7 @@ namespace ImageProcessor.Filters
             { -1, 0, 1 }
         };
 
-        /// <summary>
-        /// Gets the vertical gradient operator.
-        /// </summary>
+        /// <inheritdoc/>
         public override float[,] KernelY => new float[,]
         {
             { 1, 2, 1 },
diff --git a/src/ImageProcessor/Filters/Convolution/GuassianBlur.cs b/src/ImageProcessor/Filters/Convolution/GuassianBlur.cs
index 0973b1a61..3b64bc153 100644
--- a/src/ImageProcessor/Filters/Convolution/GuassianBlur.cs
+++ b/src/ImageProcessor/Filters/Convolution/GuassianBlur.cs
@@ -82,7 +82,7 @@ namespace ImageProcessor.Filters
         public override int Parallelism => 1;
 
         /// <inheritdoc/>
-        protected override void OnApply(Rectangle targetRectangle, Rectangle sourceRectangle)
+        protected override void OnApply(ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle)
         {
             if (this.kernelY == null)
             {
diff --git a/src/ImageProcessor/Filters/Convolution/GuassianSharpen.cs b/src/ImageProcessor/Filters/Convolution/GuassianSharpen.cs
index 1e45c09de..75eda001f 100644
--- a/src/ImageProcessor/Filters/Convolution/GuassianSharpen.cs
+++ b/src/ImageProcessor/Filters/Convolution/GuassianSharpen.cs
@@ -82,7 +82,7 @@ namespace ImageProcessor.Filters
         public override int Parallelism => 1;
 
         /// <inheritdoc/>
-        protected override void OnApply(Rectangle targetRectangle, Rectangle sourceRectangle)
+        protected override void OnApply(ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle)
         {
             if (this.kernelY == null)
             {
diff --git a/src/ImageProcessor/Filters/ImageFilterExtensions.cs b/src/ImageProcessor/Filters/ImageFilterExtensions.cs
index 343454e7a..f9a91e0f3 100644
--- a/src/ImageProcessor/Filters/ImageFilterExtensions.cs
+++ b/src/ImageProcessor/Filters/ImageFilterExtensions.cs
@@ -135,6 +135,42 @@ namespace ImageProcessor.Filters
             return source.Process(rectangle, new Contrast(amount));
         }
 
+        /// <summary>
+        /// Detects any edges within the image. Uses the <see cref="Sobel"/> filter
+        /// operating in greyscale mode.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <returns>The <see cref="Image"/>.</returns>
+        public static Image DetectEdges(this Image source)
+        {
+            return DetectEdges(source, source.Bounds, new Sobel { Greyscale = true });
+        }
+
+        /// <summary>
+        /// Detects any edges within the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="filter">The filter for detecting edges.</param>
+        /// <returns>The <see cref="Image"/>.</returns>
+        public static Image DetectEdges(this Image source, IEdgeDetectorFilter filter)
+        {
+            return DetectEdges(source, source.Bounds, filter);
+        }
+
+        /// <summary>
+        /// Detects any edges within the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="rectangle">
+        /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
+        /// </param>
+        /// <param name="filter">The filter for detecting edges.</param>
+        /// <returns>The <see cref="Image"/>.</returns>
+        public static Image DetectEdges(this Image source, Rectangle rectangle, IEdgeDetectorFilter filter)
+        {
+            return source.Process(rectangle, filter);
+        }
+
         /// <summary>
         /// Applies greyscale toning to the image.
         /// </summary>
diff --git a/src/ImageProcessor/Formats/Gif/Quantizer/OctreeQuantizer.cs b/src/ImageProcessor/Formats/Gif/Quantizer/OctreeQuantizer.cs
index 3d82fb71f..2ae1ea4b2 100644
--- a/src/ImageProcessor/Formats/Gif/Quantizer/OctreeQuantizer.cs
+++ b/src/ImageProcessor/Formats/Gif/Quantizer/OctreeQuantizer.cs
@@ -8,8 +8,6 @@ namespace ImageProcessor.Formats
     using System;
     using System.Collections.Generic;
 
-    using ImageProcessor.Common.Extensions;
-
     /// <summary>
     /// Encapsulates methods to calculate the colour palette if an image using an Octree pattern.
     /// <see href="http://msdn.microsoft.com/en-us/library/aa479306.aspx"/>
diff --git a/src/ImageProcessor/ImageProcessor.csproj b/src/ImageProcessor/ImageProcessor.csproj
index 9ce6dc4bd..14ec5b965 100644
--- a/src/ImageProcessor/ImageProcessor.csproj
+++ b/src/ImageProcessor/ImageProcessor.csproj
@@ -57,6 +57,9 @@
     <Compile Include="Filters\ColorMatrix\Saturation.cs" />
     <Compile Include="Filters\ColorMatrix\GreyscaleMode.cs" />
     <Compile Include="Filters\Brightness.cs" />
+    <Compile Include="Filters\Convolution\EdgeDetection\EdgeDetector2DFilter.cs" />
+    <Compile Include="Filters\Convolution\EdgeDetection\EdgeDetectorFilter.cs" />
+    <Compile Include="Filters\Convolution\EdgeDetection\IEdgeDetectorFilter.cs" />
     <Compile Include="Filters\Convolution\EdgeDetection\Scharr.cs" />
     <Compile Include="Filters\Convolution\EdgeDetection\RobertsCross.cs" />
     <Compile Include="Filters\Convolution\EdgeDetection\Prewitt.cs" />
diff --git a/src/ImageProcessor/ParallelImageProcessor.cs b/src/ImageProcessor/ParallelImageProcessor.cs
index 843f40b9e..200b6b183 100644
--- a/src/ImageProcessor/ParallelImageProcessor.cs
+++ b/src/ImageProcessor/ParallelImageProcessor.cs
@@ -21,7 +21,7 @@ namespace ImageProcessor
         /// <inheritdoc/>
         public void Apply(ImageBase target, ImageBase source, Rectangle sourceRectangle)
         {
-            this.OnApply(target.Bounds, sourceRectangle);
+            this.OnApply(source, target.Bounds, sourceRectangle);
 
             if (this.Parallelism > 1)
             {
@@ -66,7 +66,7 @@ namespace ImageProcessor
                 sourceRectangle = source.Bounds;
             }
 
-            this.OnApply(target.Bounds, sourceRectangle);
+            this.OnApply(source, target.Bounds, sourceRectangle);
 
             if (this.Parallelism > 1)
             {
@@ -98,6 +98,7 @@ namespace ImageProcessor
         /// <summary>
         /// This method is called before the process is applied to prepare the processor.
         /// </summary>
+        /// <param name="source">The source image. Cannot be null.</param>
         /// <param name="targetRectangle">
         /// The <see cref="Rectangle"/> structure that specifies the location and size of the drawn image.
         /// The image is scaled to fit the rectangle.
@@ -105,7 +106,7 @@ namespace ImageProcessor
         /// <param name="sourceRectangle">
         /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to draw.
         /// </param>
-        protected virtual void OnApply(Rectangle targetRectangle, Rectangle sourceRectangle)
+        protected virtual void OnApply(ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle)
         {
         }
 
diff --git a/src/ImageProcessor/Samplers/Resize.cs b/src/ImageProcessor/Samplers/Resize.cs
index 1d1484417..f43463efc 100644
--- a/src/ImageProcessor/Samplers/Resize.cs
+++ b/src/ImageProcessor/Samplers/Resize.cs
@@ -48,7 +48,7 @@ namespace ImageProcessor.Samplers
         public IResampler Sampler { get; }
 
         /// <inheritdoc/>
-        protected override void OnApply(Rectangle targetRectangle, Rectangle sourceRectangle)
+        protected override void OnApply(ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle)
         {
             this.horizontalWeights = this.PrecomputeWeights(targetRectangle.Width, sourceRectangle.Width);
             this.verticalWeights = this.PrecomputeWeights(targetRectangle.Height, sourceRectangle.Height);
diff --git a/tests/ImageProcessor.Tests/Processors/Filters/FilterTests.cs b/tests/ImageProcessor.Tests/Processors/Filters/FilterTests.cs
index c65f2381c..76b0bfdaa 100644
--- a/tests/ImageProcessor.Tests/Processors/Filters/FilterTests.cs
+++ b/tests/ImageProcessor.Tests/Processors/Filters/FilterTests.cs
@@ -37,7 +37,7 @@ namespace ImageProcessor.Tests
             { "Prewitt", new Prewitt() },
             { "RobertsCross", new RobertsCross() },
             { "Scharr", new Scharr() },
-            { "Sobel", new Sobel() },
+            { "Sobel", new Sobel {Greyscale = true} },
             { "GuassianBlur", new GuassianBlur(10) },
             { "GuassianSharpen", new GuassianSharpen(10) }
         };