From 9d46c158923f8cf89f767db5939ac04552e37e4c Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 20 Dec 2019 13:46:19 +0100
Subject: [PATCH 01/18] Added initial version of the pixel shader delegate and
 processors

---
 .../Processing/Delegates/PixelShader.cs       | 12 ++++
 .../DelegatePixelShaderProcessor.cs           | 38 +++++++++++
 .../DelegatePixelShaderProcessor{TPixel}.cs   | 66 +++++++++++++++++++
 3 files changed, 116 insertions(+)
 create mode 100644 src/ImageSharp/Processing/Delegates/PixelShader.cs
 create mode 100644 src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor.cs
 create mode 100644 src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor{TPixel}.cs

diff --git a/src/ImageSharp/Processing/Delegates/PixelShader.cs b/src/ImageSharp/Processing/Delegates/PixelShader.cs
new file mode 100644
index 0000000000..fd051c0e6a
--- /dev/null
+++ b/src/ImageSharp/Processing/Delegates/PixelShader.cs
@@ -0,0 +1,12 @@
+using System;
+using System.Numerics;
+
+namespace SixLabors.ImageSharp.Processing.Delegates
+{
+    /// <summary>
+    /// A <see langword="delegate"/> representing a user defined pixel shader.
+    /// </summary>
+    /// <param name="span">The target row of <see cref="Vector4"/> pixels to process.</param>
+    /// <remarks>The <see cref="Vector4.X"/>, <see cref="Vector4.Y"/>, <see cref="Vector4.Z"/>, and <see cref="Vector4.W"/> fields map the RGBA channels respectively.</remarks>
+    public delegate void PixelShader(Span<Vector4> span);
+}
diff --git a/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor.cs
new file mode 100644
index 0000000000..13ac957ec2
--- /dev/null
+++ b/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor.cs
@@ -0,0 +1,38 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing.Delegates;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Processors
+{
+    /// <summary>
+    /// Applies a user defined pixel shader effect through a given delegate.
+    /// </summary>
+    public sealed class DelegatePixelShaderProcessor : IImageProcessor
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DelegatePixelShaderProcessor"/> class.
+        /// </summary>
+        /// <param name="pixelShader">
+        /// The user defined pixel shader to use to modify images.
+        /// </param>
+        public DelegatePixelShaderProcessor(PixelShader pixelShader)
+        {
+            this.PixelShader = pixelShader;
+        }
+
+        /// <summary>
+        /// Gets the user defined pixel shader.
+        /// </summary>
+        public PixelShader PixelShader { get; }
+
+        /// <inheritdoc />
+        public IImageProcessor<TPixel> CreatePixelSpecificProcessor<TPixel>(Image<TPixel> source, Rectangle sourceRectangle)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            return new DelegatePixelShaderProcessor<TPixel>(this, source, sourceRectangle);
+        }
+    }
+}
diff --git a/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor{TPixel}.cs
new file mode 100644
index 0000000000..e6119f2c85
--- /dev/null
+++ b/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor{TPixel}.cs
@@ -0,0 +1,66 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Numerics;
+
+using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing.Delegates;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Processors
+{
+    /// <summary>
+    /// Performs simple binary threshold filtering against an image.
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format.</typeparam>
+    internal class DelegatePixelShaderProcessor<TPixel> : ImageProcessor<TPixel>
+        where TPixel : struct, IPixel<TPixel>
+    {
+        /// <summary>
+        /// The user defined pixel shader.
+        /// </summary>
+        private readonly PixelShader pixelShader;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DelegatePixelShaderProcessor{TPixel}"/> class.
+        /// </summary>
+        /// <param name="definition">The <see cref="DelegatePixelShaderProcessor"/> defining the processor parameters.</param>
+        /// <param name="source">The source <see cref="Image{TPixel}"/> for the current processor instance.</param>
+        /// <param name="sourceRectangle">The source area to process for the current processor instance.</param>
+        public DelegatePixelShaderProcessor(DelegatePixelShaderProcessor definition, Image<TPixel> source, Rectangle sourceRectangle)
+            : base(source, sourceRectangle)
+        {
+            this.pixelShader = definition.PixelShader;
+        }
+
+        /// <inheritdoc/>
+        protected override void OnFrameApply(ImageFrame<TPixel> source)
+        {
+            var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
+            int startX = interest.X;
+            PixelShader pixelShader = this.pixelShader;
+
+            ParallelHelper.IterateRowsWithTempBuffer<Vector4>(
+                interest,
+                this.Configuration,
+                (rows, vectorBuffer) =>
+                {
+                    for (int y = rows.Min; y < rows.Max; y++)
+                    {
+                        Span<Vector4> vectorSpan = vectorBuffer.Span;
+                        int length = vectorSpan.Length;
+                        Span<TPixel> rowSpan = source.GetPixelRowSpan(y).Slice(startX, length);
+                        PixelOperations<TPixel>.Instance.ToVector4(this.Configuration, rowSpan, vectorSpan);
+
+                        // Run the user defined pixel shader on the current row of pixels
+                        pixelShader(vectorSpan);
+
+                        PixelOperations<TPixel>.Instance.FromVector4Destructive(this.Configuration, vectorSpan, rowSpan);
+                    }
+                });
+        }
+    }
+}

From 9e03619e2dc4b52cc040aa25fbc67e98a1f01a35 Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 20 Dec 2019 13:49:15 +0100
Subject: [PATCH 02/18] Added PixelShaderExtensions class

---
 .../Extensions/PixelShaderExtensions.cs       | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs

diff --git a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
new file mode 100644
index 0000000000..96783ba6ee
--- /dev/null
+++ b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
@@ -0,0 +1,36 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Processing.Delegates;
+using SixLabors.ImageSharp.Processing.Processors;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing
+{
+    /// <summary>
+    /// Defines extension methods that allow the application of user defined pixel shaders to an <see cref="Image"/>.
+    /// </summary>
+    public static class PixelShaderExtensions
+    {
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PixelShader pixelShader)
+            => source.ApplyProcessor(new DelegatePixelShaderProcessor(pixelShader));
+
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</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 BlackWhite(this IImageProcessingContext source, PixelShader pixelShader, Rectangle rectangle)
+            => source.ApplyProcessor(new DelegatePixelShaderProcessor(pixelShader), rectangle);
+    }
+}

From bde0790eab04bc90479f39489be34d0d23a9126f Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 20 Dec 2019 14:16:34 +0100
Subject: [PATCH 03/18] Minor code refactoring

---
 src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs   | 1 +
 .../{ => PixelShading}/DelegatePixelShaderProcessor.cs          | 2 +-
 .../{ => PixelShading}/DelegatePixelShaderProcessor{TPixel}.cs  | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)
 rename src/ImageSharp/Processing/Processors/{ => PixelShading}/DelegatePixelShaderProcessor.cs (95%)
 rename src/ImageSharp/Processing/Processors/{ => PixelShading}/DelegatePixelShaderProcessor{TPixel}.cs (97%)

diff --git a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
index 96783ba6ee..bad705a4d8 100644
--- a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
+++ b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
@@ -3,6 +3,7 @@
 
 using SixLabors.ImageSharp.Processing.Delegates;
 using SixLabors.ImageSharp.Processing.Processors;
+using SixLabors.ImageSharp.Processing.Processors.PixelShading;
 using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing
diff --git a/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor.cs
similarity index 95%
rename from src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor.cs
rename to src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor.cs
index 13ac957ec2..b09385ff3a 100644
--- a/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor.cs
@@ -5,7 +5,7 @@ using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing.Delegates;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Processing.Processors
+namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
 {
     /// <summary>
     /// Applies a user defined pixel shader effect through a given delegate.
diff --git a/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs
similarity index 97%
rename from src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor{TPixel}.cs
rename to src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs
index e6119f2c85..c773e8b808 100644
--- a/src/ImageSharp/Processing/Processors/DelegatePixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs
@@ -10,7 +10,7 @@ using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing.Delegates;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Processing.Processors
+namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
 {
     /// <summary>
     /// Performs simple binary threshold filtering against an image.

From 4a193aa5ea2e0ca3fe19ca43218f2831864a817d Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 20 Dec 2019 14:20:23 +0100
Subject: [PATCH 04/18] Added PositionAwarePixelShader types

---
 .../Delegates/PositionAwarePixelShader.cs     | 14 ++++
 .../DelegatePixelShaderProcessor{TPixel}.cs   |  2 +-
 .../PositionAwarePixelShaderProcessor.cs      | 38 +++++++++++
 ...sitionAwarePixelShaderProcessor{TPixel}.cs | 65 +++++++++++++++++++
 4 files changed, 118 insertions(+), 1 deletion(-)
 create mode 100644 src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs
 create mode 100644 src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
 create mode 100644 src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs

diff --git a/src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs b/src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs
new file mode 100644
index 0000000000..08314600a2
--- /dev/null
+++ b/src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs
@@ -0,0 +1,14 @@
+using System;
+using System.Numerics;
+
+namespace SixLabors.ImageSharp.Processing.Delegates
+{
+    /// <summary>
+    /// A <see langword="delegate"/> representing a user defined pixel shader.
+    /// </summary>
+    /// <param name="span">The target row of <see cref="Vector4"/> pixels to process.</param>
+    /// <param name="offsetY">The initial vertical offset for the input pixels to process.</param>
+    /// <param name="offsetX">The initial horizontal offset for the input pixels to process.</param>
+    /// <remarks>The <see cref="Vector4.X"/>, <see cref="Vector4.Y"/>, <see cref="Vector4.Z"/>, and <see cref="Vector4.W"/> fields map the RGBA channels respectively.</remarks>
+    public delegate void PositionAwarePixelShader(Span<Vector4> span, int offsetY, int offsetX);
+}
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs
index c773e8b808..d15614cc4c 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs
@@ -13,7 +13,7 @@ using SixLabors.Primitives;
 namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
 {
     /// <summary>
-    /// Performs simple binary threshold filtering against an image.
+    /// Applies a user defined pixel shader effect through a given delegate.
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
     internal class DelegatePixelShaderProcessor<TPixel> : ImageProcessor<TPixel>
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
new file mode 100644
index 0000000000..60125b2e27
--- /dev/null
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
@@ -0,0 +1,38 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing.Delegates;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
+{
+    /// <summary>
+    /// Applies a user defined pixel shader effect through a given delegate.
+    /// </summary>
+    public sealed class PositionAwarePixelShaderProcessor : IImageProcessor
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PositionAwarePixelShaderProcessor"/> class.
+        /// </summary>
+        /// <param name="pixelShader">
+        /// The user defined pixel shader to use to modify images.
+        /// </param>
+        public PositionAwarePixelShaderProcessor(PositionAwarePixelShader pixelShader)
+        {
+            this.PixelShader = pixelShader;
+        }
+
+        /// <summary>
+        /// Gets the user defined pixel shader.
+        /// </summary>
+        public PositionAwarePixelShader PixelShader { get; }
+
+        /// <inheritdoc />
+        public IImageProcessor<TPixel> CreatePixelSpecificProcessor<TPixel>(Image<TPixel> source, Rectangle sourceRectangle)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            return new PositionAwarePixelShader<TPixel>(this, source, sourceRectangle);
+        }
+    }
+}
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
new file mode 100644
index 0000000000..55ad325ad7
--- /dev/null
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
@@ -0,0 +1,65 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Numerics;
+
+using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing.Delegates;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
+{
+    /// <summary>
+    /// Applies a user defined pixel shader effect through a given delegate.
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format.</typeparam>
+    internal class PositionAwarePixelShaderProcessor<TPixel> : ImageProcessor<TPixel>
+        where TPixel : struct, IPixel<TPixel>
+    {
+        /// <summary>
+        /// The user defined pixel shader.
+        /// </summary>
+        private readonly PositionAwarePixelShader pixelShader;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PositionAwarePixelShaderProcessor{TPixel}"/> class.
+        /// </summary>
+        /// <param name="definition">The <see cref="PositionAwarePixelShaderProcessor"/> defining the processor parameters.</param>
+        /// <param name="source">The source <see cref="Image{TPixel}"/> for the current processor instance.</param>
+        /// <param name="sourceRectangle">The source area to process for the current processor instance.</param>
+        public PositionAwarePixelShaderProcessor(PositionAwarePixelShaderProcessor definition, Image<TPixel> source, Rectangle sourceRectangle)
+            : base(source, sourceRectangle)
+        {
+            this.pixelShader = definition.PixelShader;
+        }
+
+        /// <inheritdoc/>
+        protected override void OnFrameApply(ImageFrame<TPixel> source)
+        {
+            var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
+            int startX = interest.X;
+            PositionAwarePixelShader pixelShader = this.pixelShader;
+
+            ParallelHelper.IterateRowsWithTempBuffer<Vector4>(
+                interest,
+                this.Configuration,
+                (rows, vectorBuffer) =>
+                {
+                    for (int y = rows.Min; y < rows.Max; y++)
+                    {
+                        Span<Vector4> vectorSpan = vectorBuffer.Span;
+                        int length = vectorSpan.Length;
+                        Span<TPixel> rowSpan = source.GetPixelRowSpan(y).Slice(startX, length);
+                        PixelOperations<TPixel>.Instance.ToVector4(this.Configuration, rowSpan, vectorSpan);
+
+                        pixelShader(vectorSpan, y, startX);
+
+                        PixelOperations<TPixel>.Instance.FromVector4Destructive(this.Configuration, vectorSpan, rowSpan);
+                    }
+                });
+        }
+    }
+}

From 21729331f22fd0dd4688243939be2773c426283d Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 20 Dec 2019 14:21:11 +0100
Subject: [PATCH 05/18] Minor code refactoring

---
 .../Processing/Extensions/PixelShaderExtensions.cs        | 5 ++---
 ...atePixelShaderProcessor.cs => PixelShaderProcessor.cs} | 8 ++++----
 ...ocessor{TPixel}.cs => PixelShaderProcessor{TPixel}.cs} | 8 ++++----
 3 files changed, 10 insertions(+), 11 deletions(-)
 rename src/ImageSharp/Processing/Processors/PixelShading/{DelegatePixelShaderProcessor.cs => PixelShaderProcessor.cs} (75%)
 rename src/ImageSharp/Processing/Processors/PixelShading/{DelegatePixelShaderProcessor{TPixel}.cs => PixelShaderProcessor{TPixel}.cs} (84%)

diff --git a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
index bad705a4d8..26b6de3db1 100644
--- a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
+++ b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0.
 
 using SixLabors.ImageSharp.Processing.Delegates;
-using SixLabors.ImageSharp.Processing.Processors;
 using SixLabors.ImageSharp.Processing.Processors.PixelShading;
 using SixLabors.Primitives;
 
@@ -20,7 +19,7 @@ namespace SixLabors.ImageSharp.Processing
         /// <param name="pixelShader">The user defined pixel shader to use to modify images.</param>
         /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
         public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PixelShader pixelShader)
-            => source.ApplyProcessor(new DelegatePixelShaderProcessor(pixelShader));
+            => source.ApplyProcessor(new PixelShaderProcessor(pixelShader));
 
         /// <summary>
         /// Applies a user defined pixel shader to the image.
@@ -32,6 +31,6 @@ namespace SixLabors.ImageSharp.Processing
         /// </param>
         /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
         public static IImageProcessingContext BlackWhite(this IImageProcessingContext source, PixelShader pixelShader, Rectangle rectangle)
-            => source.ApplyProcessor(new DelegatePixelShaderProcessor(pixelShader), rectangle);
+            => source.ApplyProcessor(new PixelShaderProcessor(pixelShader), rectangle);
     }
 }
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs
similarity index 75%
rename from src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor.cs
rename to src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs
index b09385ff3a..30ba4222ea 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs
@@ -10,15 +10,15 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
     /// <summary>
     /// Applies a user defined pixel shader effect through a given delegate.
     /// </summary>
-    public sealed class DelegatePixelShaderProcessor : IImageProcessor
+    public sealed class PixelShaderProcessor : IImageProcessor
     {
         /// <summary>
-        /// Initializes a new instance of the <see cref="DelegatePixelShaderProcessor"/> class.
+        /// Initializes a new instance of the <see cref="PixelShaderProcessor"/> class.
         /// </summary>
         /// <param name="pixelShader">
         /// The user defined pixel shader to use to modify images.
         /// </param>
-        public DelegatePixelShaderProcessor(PixelShader pixelShader)
+        public PixelShaderProcessor(PixelShader pixelShader)
         {
             this.PixelShader = pixelShader;
         }
@@ -32,7 +32,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
         public IImageProcessor<TPixel> CreatePixelSpecificProcessor<TPixel>(Image<TPixel> source, Rectangle sourceRectangle)
             where TPixel : struct, IPixel<TPixel>
         {
-            return new DelegatePixelShaderProcessor<TPixel>(this, source, sourceRectangle);
+            return new PixelShaderProcessor<TPixel>(this, source, sourceRectangle);
         }
     }
 }
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
similarity index 84%
rename from src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs
rename to src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
index d15614cc4c..b856355aed 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/DelegatePixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
@@ -16,7 +16,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
     /// Applies a user defined pixel shader effect through a given delegate.
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal class DelegatePixelShaderProcessor<TPixel> : ImageProcessor<TPixel>
+    internal class PixelShaderProcessor<TPixel> : ImageProcessor<TPixel>
         where TPixel : struct, IPixel<TPixel>
     {
         /// <summary>
@@ -25,12 +25,12 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
         private readonly PixelShader pixelShader;
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="DelegatePixelShaderProcessor{TPixel}"/> class.
+        /// Initializes a new instance of the <see cref="PixelShaderProcessor{TPixel}"/> class.
         /// </summary>
-        /// <param name="definition">The <see cref="DelegatePixelShaderProcessor"/> defining the processor parameters.</param>
+        /// <param name="definition">The <see cref="PixelShaderProcessor"/> defining the processor parameters.</param>
         /// <param name="source">The source <see cref="Image{TPixel}"/> for the current processor instance.</param>
         /// <param name="sourceRectangle">The source area to process for the current processor instance.</param>
-        public DelegatePixelShaderProcessor(DelegatePixelShaderProcessor definition, Image<TPixel> source, Rectangle sourceRectangle)
+        public PixelShaderProcessor(PixelShaderProcessor definition, Image<TPixel> source, Rectangle sourceRectangle)
             : base(source, sourceRectangle)
         {
             this.pixelShader = definition.PixelShader;

From 429d9a540669e2008b9af462bdadfd06a3aa9a75 Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 20 Dec 2019 14:21:50 +0100
Subject: [PATCH 06/18] Added new pixel shader extension methods

---
 .../Extensions/PixelShaderExtensions.cs       | 23 ++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
index 26b6de3db1..51d37caad4 100644
--- a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
+++ b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
@@ -30,7 +30,28 @@ namespace SixLabors.ImageSharp.Processing
         /// 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 BlackWhite(this IImageProcessingContext source, PixelShader pixelShader, Rectangle rectangle)
+        public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PixelShader pixelShader, Rectangle rectangle)
             => source.ApplyProcessor(new PixelShaderProcessor(pixelShader), rectangle);
+
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PositionAwarePixelShader pixelShader)
+            => source.ApplyProcessor(new PositionAwarePixelShaderProcessor(pixelShader));
+
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</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 ApplyPixelShaderProcessor(this IImageProcessingContext source, PositionAwarePixelShader pixelShader, Rectangle rectangle)
+            => source.ApplyProcessor(new PositionAwarePixelShaderProcessor(pixelShader), rectangle);
     }
 }

From d91694d9ff695c553592252b70173bb1590348f8 Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 20 Dec 2019 14:38:55 +0100
Subject: [PATCH 07/18] Minor code refactoring

---
 .../Abstract/PixelShaderProcessorBase.cs      | 64 +++++++++++++++++++
 .../PixelShaderProcessor{TPixel}.cs           | 31 +--------
 ...sitionAwarePixelShaderProcessor{TPixel}.cs | 30 +--------
 3 files changed, 70 insertions(+), 55 deletions(-)
 create mode 100644 src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs

diff --git a/src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs b/src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs
new file mode 100644
index 0000000000..4d2cb233b0
--- /dev/null
+++ b/src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs
@@ -0,0 +1,64 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Numerics;
+
+using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing.Processors.PixelShading.Abstract
+{
+    /// <summary>
+    /// Applies a user defined pixel shader effect through a given delegate.
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format.</typeparam>
+    internal abstract class PixelShaderProcessorBase<TPixel> : ImageProcessor<TPixel>
+        where TPixel : struct, IPixel<TPixel>
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PixelShaderProcessorBase{TPixel}"/> class.
+        /// </summary>
+        /// <param name="source">The source <see cref="Image{TPixel}"/> for the current processor instance.</param>
+        /// <param name="sourceRectangle">The source area to process for the current processor instance.</param>
+        protected PixelShaderProcessorBase(Image<TPixel> source, Rectangle sourceRectangle)
+            : base(source, sourceRectangle)
+        { }
+
+        /// <inheritdoc/>
+        protected override void OnFrameApply(ImageFrame<TPixel> source)
+        {
+            var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
+            int startX = interest.X;
+
+            ParallelHelper.IterateRowsWithTempBuffer<Vector4>(
+                interest,
+                this.Configuration,
+                (rows, vectorBuffer) =>
+                {
+                    for (int y = rows.Min; y < rows.Max; y++)
+                    {
+                        Span<Vector4> vectorSpan = vectorBuffer.Span;
+                        int length = vectorSpan.Length;
+                        Span<TPixel> rowSpan = source.GetPixelRowSpan(y).Slice(startX, length);
+                        PixelOperations<TPixel>.Instance.ToVector4(this.Configuration, rowSpan, vectorSpan);
+
+                        // Run the user defined pixel shader on the current row of pixels
+                        this.ApplyPixelShader(vectorSpan, y, startX);
+
+                        PixelOperations<TPixel>.Instance.FromVector4Destructive(this.Configuration, vectorSpan, rowSpan);
+                    }
+                });
+        }
+
+        /// <summary>
+        /// Applies the current pixel shader effect on a target row of preprocessed pixels.
+        /// </summary>
+        /// <param name="span">The target row of <see cref="Vector4"/> pixels to process.</param>
+        /// <param name="offsetY">The initial vertical offset for the input pixels to process.</param>
+        /// <param name="offsetX">The initial horizontal offset for the input pixels to process.</param>
+        protected abstract void ApplyPixelShader(Span<Vector4> span, int offsetY, int offsetX);
+    }
+}
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
index b856355aed..70728a4ecb 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
@@ -4,10 +4,9 @@
 using System;
 using System.Numerics;
 
-using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing.Delegates;
+using SixLabors.ImageSharp.Processing.Processors.PixelShading.Abstract;
 using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
@@ -16,7 +15,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
     /// Applies a user defined pixel shader effect through a given delegate.
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal class PixelShaderProcessor<TPixel> : ImageProcessor<TPixel>
+    internal class PixelShaderProcessor<TPixel> : PixelShaderProcessorBase<TPixel>
         where TPixel : struct, IPixel<TPixel>
     {
         /// <summary>
@@ -37,30 +36,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
         }
 
         /// <inheritdoc/>
-        protected override void OnFrameApply(ImageFrame<TPixel> source)
-        {
-            var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
-            int startX = interest.X;
-            PixelShader pixelShader = this.pixelShader;
-
-            ParallelHelper.IterateRowsWithTempBuffer<Vector4>(
-                interest,
-                this.Configuration,
-                (rows, vectorBuffer) =>
-                {
-                    for (int y = rows.Min; y < rows.Max; y++)
-                    {
-                        Span<Vector4> vectorSpan = vectorBuffer.Span;
-                        int length = vectorSpan.Length;
-                        Span<TPixel> rowSpan = source.GetPixelRowSpan(y).Slice(startX, length);
-                        PixelOperations<TPixel>.Instance.ToVector4(this.Configuration, rowSpan, vectorSpan);
-
-                        // Run the user defined pixel shader on the current row of pixels
-                        pixelShader(vectorSpan);
-
-                        PixelOperations<TPixel>.Instance.FromVector4Destructive(this.Configuration, vectorSpan, rowSpan);
-                    }
-                });
-        }
+        protected override void ApplyPixelShader(Span<Vector4> span, int offsetY, int offsetX) => this.pixelShader(span);
     }
 }
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
index 55ad325ad7..7c5eff5979 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
@@ -4,10 +4,9 @@
 using System;
 using System.Numerics;
 
-using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing.Delegates;
+using SixLabors.ImageSharp.Processing.Processors.PixelShading.Abstract;
 using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
@@ -16,7 +15,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
     /// Applies a user defined pixel shader effect through a given delegate.
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal class PositionAwarePixelShaderProcessor<TPixel> : ImageProcessor<TPixel>
+    internal class PositionAwarePixelShaderProcessor<TPixel> : PixelShaderProcessorBase<TPixel>
         where TPixel : struct, IPixel<TPixel>
     {
         /// <summary>
@@ -37,29 +36,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
         }
 
         /// <inheritdoc/>
-        protected override void OnFrameApply(ImageFrame<TPixel> source)
-        {
-            var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
-            int startX = interest.X;
-            PositionAwarePixelShader pixelShader = this.pixelShader;
-
-            ParallelHelper.IterateRowsWithTempBuffer<Vector4>(
-                interest,
-                this.Configuration,
-                (rows, vectorBuffer) =>
-                {
-                    for (int y = rows.Min; y < rows.Max; y++)
-                    {
-                        Span<Vector4> vectorSpan = vectorBuffer.Span;
-                        int length = vectorSpan.Length;
-                        Span<TPixel> rowSpan = source.GetPixelRowSpan(y).Slice(startX, length);
-                        PixelOperations<TPixel>.Instance.ToVector4(this.Configuration, rowSpan, vectorSpan);
-
-                        pixelShader(vectorSpan, y, startX);
-
-                        PixelOperations<TPixel>.Instance.FromVector4Destructive(this.Configuration, vectorSpan, rowSpan);
-                    }
-                });
-        }
+        protected override void ApplyPixelShader(Span<Vector4> span, int offsetY, int offsetX) => this.pixelShader(span, offsetY, offsetX);
     }
 }

From 8c2662448769e75770297c831b09141146421eb7 Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 20 Dec 2019 18:19:16 +0100
Subject: [PATCH 08/18] Fixed a typo

---
 .../PixelShading/PositionAwarePixelShaderProcessor.cs           | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
index 60125b2e27..a1fdc60821 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
@@ -32,7 +32,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
         public IImageProcessor<TPixel> CreatePixelSpecificProcessor<TPixel>(Image<TPixel> source, Rectangle sourceRectangle)
             where TPixel : struct, IPixel<TPixel>
         {
-            return new PositionAwarePixelShader<TPixel>(this, source, sourceRectangle);
+            return new PositionAwarePixelShaderProcessor<TPixel>(this, source, sourceRectangle);
         }
     }
 }

From ca3c284e6aa8deca4e2d380b72d225a64c81923c Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 20 Dec 2019 19:04:31 +0100
Subject: [PATCH 09/18] Made StyleCode happy

---
 src/ImageSharp/Processing/Delegates/PixelShader.cs             | 3 +++
 .../Processing/Delegates/PositionAwarePixelShader.cs           | 3 +++
 .../PixelShading/Abstract/PixelShaderProcessorBase.cs          | 3 ++-
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/ImageSharp/Processing/Delegates/PixelShader.cs b/src/ImageSharp/Processing/Delegates/PixelShader.cs
index fd051c0e6a..72895f14b0 100644
--- a/src/ImageSharp/Processing/Delegates/PixelShader.cs
+++ b/src/ImageSharp/Processing/Delegates/PixelShader.cs
@@ -1,3 +1,6 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
 using System;
 using System.Numerics;
 
diff --git a/src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs b/src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs
index 08314600a2..8455b9b058 100644
--- a/src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs
+++ b/src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs
@@ -1,3 +1,6 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
 using System;
 using System.Numerics;
 
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs b/src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs
index 4d2cb233b0..1af50197aa 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs
@@ -25,7 +25,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.PixelShading.Abstract
         /// <param name="sourceRectangle">The source area to process for the current processor instance.</param>
         protected PixelShaderProcessorBase(Image<TPixel> source, Rectangle sourceRectangle)
             : base(source, sourceRectangle)
-        { }
+        {
+        }
 
         /// <inheritdoc/>
         protected override void OnFrameApply(ImageFrame<TPixel> source)

From 62272a32831f4d67df876a74e6351e076863a4aa Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Thu, 26 Dec 2019 11:17:12 +0100
Subject: [PATCH 10/18] Moved delegate types

---
 src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs   | 1 -
 src/ImageSharp/Processing/{Delegates => }/PixelShader.cs        | 2 +-
 .../Processing/{Delegates => }/PositionAwarePixelShader.cs      | 2 +-
 .../Processing/Processors/PixelShading/PixelShaderProcessor.cs  | 1 -
 .../Processors/PixelShading/PixelShaderProcessor{TPixel}.cs     | 1 -
 .../PixelShading/PositionAwarePixelShaderProcessor.cs           | 1 -
 .../PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs   | 1 -
 7 files changed, 2 insertions(+), 7 deletions(-)
 rename src/ImageSharp/Processing/{Delegates => }/PixelShader.cs (91%)
 rename src/ImageSharp/Processing/{Delegates => }/PositionAwarePixelShader.cs (94%)

diff --git a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
index 51d37caad4..36529eb70c 100644
--- a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
+++ b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using SixLabors.ImageSharp.Processing.Delegates;
 using SixLabors.ImageSharp.Processing.Processors.PixelShading;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Delegates/PixelShader.cs b/src/ImageSharp/Processing/PixelShader.cs
similarity index 91%
rename from src/ImageSharp/Processing/Delegates/PixelShader.cs
rename to src/ImageSharp/Processing/PixelShader.cs
index 72895f14b0..0245931fb5 100644
--- a/src/ImageSharp/Processing/Delegates/PixelShader.cs
+++ b/src/ImageSharp/Processing/PixelShader.cs
@@ -4,7 +4,7 @@
 using System;
 using System.Numerics;
 
-namespace SixLabors.ImageSharp.Processing.Delegates
+namespace SixLabors.ImageSharp.Processing
 {
     /// <summary>
     /// A <see langword="delegate"/> representing a user defined pixel shader.
diff --git a/src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs b/src/ImageSharp/Processing/PositionAwarePixelShader.cs
similarity index 94%
rename from src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs
rename to src/ImageSharp/Processing/PositionAwarePixelShader.cs
index 8455b9b058..63e9246b41 100644
--- a/src/ImageSharp/Processing/Delegates/PositionAwarePixelShader.cs
+++ b/src/ImageSharp/Processing/PositionAwarePixelShader.cs
@@ -4,7 +4,7 @@
 using System;
 using System.Numerics;
 
-namespace SixLabors.ImageSharp.Processing.Delegates
+namespace SixLabors.ImageSharp.Processing
 {
     /// <summary>
     /// A <see langword="delegate"/> representing a user defined pixel shader.
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs
index 30ba4222ea..c0b333a691 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs
@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0.
 
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Processing.Delegates;
 using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
index 70728a4ecb..f3f8f25983 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
@@ -5,7 +5,6 @@ using System;
 using System.Numerics;
 
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Processing.Delegates;
 using SixLabors.ImageSharp.Processing.Processors.PixelShading.Abstract;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
index a1fdc60821..c06d460486 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0.
 
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Processing.Delegates;
 using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
index 7c5eff5979..bca3286eb2 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
@@ -5,7 +5,6 @@ using System;
 using System.Numerics;
 
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Processing.Delegates;
 using SixLabors.ImageSharp.Processing.Processors.PixelShading.Abstract;
 using SixLabors.Primitives;
 

From 8d2672c0b33880cdcce115493878e555ab564f6d Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Thu, 26 Dec 2019 11:20:12 +0100
Subject: [PATCH 11/18] Moved pixel shader processor types

---
 src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs  | 2 +-
 .../{PixelShading => Effects}/PixelShaderProcessor.cs          | 2 +-
 .../Abstract => Effects}/PixelShaderProcessorBase.cs           | 2 +-
 .../{PixelShading => Effects}/PixelShaderProcessor{TPixel}.cs  | 3 +--
 .../PositionAwarePixelShaderProcessor.cs                       | 2 +-
 .../PositionAwarePixelShaderProcessor{TPixel}.cs               | 3 +--
 6 files changed, 6 insertions(+), 8 deletions(-)
 rename src/ImageSharp/Processing/Processors/{PixelShading => Effects}/PixelShaderProcessor.cs (94%)
 rename src/ImageSharp/Processing/Processors/{PixelShading/Abstract => Effects}/PixelShaderProcessorBase.cs (97%)
 rename src/ImageSharp/Processing/Processors/{PixelShading => Effects}/PixelShaderProcessor{TPixel}.cs (91%)
 rename src/ImageSharp/Processing/Processors/{PixelShading => Effects}/PositionAwarePixelShaderProcessor.cs (95%)
 rename src/ImageSharp/Processing/Processors/{PixelShading => Effects}/PositionAwarePixelShaderProcessor{TPixel}.cs (92%)

diff --git a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
index 36529eb70c..30848e346c 100644
--- a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
+++ b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using SixLabors.ImageSharp.Processing.Processors.PixelShading;
+using SixLabors.ImageSharp.Processing.Processors.Effects;
 using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor.cs
similarity index 94%
rename from src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs
rename to src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor.cs
index c0b333a691..6c44199da0 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor.cs
@@ -4,7 +4,7 @@
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
+namespace SixLabors.ImageSharp.Processing.Processors.Effects
 {
     /// <summary>
     /// Applies a user defined pixel shader effect through a given delegate.
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
similarity index 97%
rename from src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs
rename to src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
index 1af50197aa..a8e032ee17 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/Abstract/PixelShaderProcessorBase.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
@@ -9,7 +9,7 @@ using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Processing.Processors.PixelShading.Abstract
+namespace SixLabors.ImageSharp.Processing.Processors.Effects
 {
     /// <summary>
     /// Applies a user defined pixel shader effect through a given delegate.
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs
similarity index 91%
rename from src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
rename to src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs
index f3f8f25983..29e3ab5a9b 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs
@@ -5,10 +5,9 @@ using System;
 using System.Numerics;
 
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Processing.Processors.PixelShading.Abstract;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
+namespace SixLabors.ImageSharp.Processing.Processors.Effects
 {
     /// <summary>
     /// Applies a user defined pixel shader effect through a given delegate.
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor.cs
similarity index 95%
rename from src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
rename to src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor.cs
index c06d460486..a83e8b5a42 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor.cs
@@ -4,7 +4,7 @@
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
+namespace SixLabors.ImageSharp.Processing.Processors.Effects
 {
     /// <summary>
     /// Applies a user defined pixel shader effect through a given delegate.
diff --git a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs
similarity index 92%
rename from src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
rename to src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs
index bca3286eb2..6c4eee35f5 100644
--- a/src/ImageSharp/Processing/Processors/PixelShading/PositionAwarePixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs
@@ -5,10 +5,9 @@ using System;
 using System.Numerics;
 
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.ImageSharp.Processing.Processors.PixelShading.Abstract;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.Processing.Processors.PixelShading
+namespace SixLabors.ImageSharp.Processing.Processors.Effects
 {
     /// <summary>
     /// Applies a user defined pixel shader effect through a given delegate.

From 14ecd52c9bd3089389e158c17146fe326cbf78ca Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Thu, 26 Dec 2019 11:27:21 +0100
Subject: [PATCH 12/18] Added support for custom pixel modifiers

---
 .../Effects/PixelShaderProcessor.cs           | 24 +++++++++++++++++++
 .../Effects/PixelShaderProcessorBase.cs       | 13 +++++++---
 .../Effects/PixelShaderProcessor{TPixel}.cs   |  2 +-
 .../PositionAwarePixelShaderProcessor.cs      | 24 +++++++++++++++++++
 ...sitionAwarePixelShaderProcessor{TPixel}.cs |  2 +-
 5 files changed, 60 insertions(+), 5 deletions(-)

diff --git a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor.cs
index 6c44199da0..2a271bef3c 100644
--- a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor.cs
@@ -11,6 +11,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
     /// </summary>
     public sealed class PixelShaderProcessor : IImageProcessor
     {
+        /// <summary>
+        /// The default <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.
+        /// </summary>
+        public const PixelConversionModifiers DefaultModifiers = PixelConversionModifiers.None;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="PixelShaderProcessor"/> class.
         /// </summary>
@@ -20,6 +25,20 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         public PixelShaderProcessor(PixelShader pixelShader)
         {
             this.PixelShader = pixelShader;
+            this.Modifiers = DefaultModifiers;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PixelShaderProcessor"/> class.
+        /// </summary>
+        /// <param name="pixelShader">
+        /// The user defined pixel shader to use to modify images.
+        /// </param>
+        /// <param name="modifiers">The <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.</param>
+        public PixelShaderProcessor(PixelShader pixelShader, PixelConversionModifiers modifiers)
+        {
+            this.PixelShader = pixelShader;
+            this.Modifiers = modifiers;
         }
 
         /// <summary>
@@ -27,6 +46,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         /// </summary>
         public PixelShader PixelShader { get; }
 
+        /// <summary>
+        /// Gets the <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.
+        /// </summary>
+        public PixelConversionModifiers Modifiers { get; }
+
         /// <inheritdoc />
         public IImageProcessor<TPixel> CreatePixelSpecificProcessor<TPixel>(Image<TPixel> source, Rectangle sourceRectangle)
             where TPixel : struct, IPixel<TPixel>
diff --git a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
index a8e032ee17..f1245ca510 100644
--- a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
@@ -18,14 +18,21 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
     internal abstract class PixelShaderProcessorBase<TPixel> : ImageProcessor<TPixel>
         where TPixel : struct, IPixel<TPixel>
     {
+        /// <summary>
+        /// The <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.
+        /// </summary>
+        private readonly PixelConversionModifiers modifiers;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="PixelShaderProcessorBase{TPixel}"/> class.
         /// </summary>
+        /// <param name="modifiers">The <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.</param>
         /// <param name="source">The source <see cref="Image{TPixel}"/> for the current processor instance.</param>
         /// <param name="sourceRectangle">The source area to process for the current processor instance.</param>
-        protected PixelShaderProcessorBase(Image<TPixel> source, Rectangle sourceRectangle)
+        protected PixelShaderProcessorBase(PixelConversionModifiers modifiers, Image<TPixel> source, Rectangle sourceRectangle)
             : base(source, sourceRectangle)
         {
+            this.modifiers = modifiers;
         }
 
         /// <inheritdoc/>
@@ -44,12 +51,12 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
                         Span<Vector4> vectorSpan = vectorBuffer.Span;
                         int length = vectorSpan.Length;
                         Span<TPixel> rowSpan = source.GetPixelRowSpan(y).Slice(startX, length);
-                        PixelOperations<TPixel>.Instance.ToVector4(this.Configuration, rowSpan, vectorSpan);
+                        PixelOperations<TPixel>.Instance.ToVector4(this.Configuration, rowSpan, vectorSpan, this.modifiers);
 
                         // Run the user defined pixel shader on the current row of pixels
                         this.ApplyPixelShader(vectorSpan, y, startX);
 
-                        PixelOperations<TPixel>.Instance.FromVector4Destructive(this.Configuration, vectorSpan, rowSpan);
+                        PixelOperations<TPixel>.Instance.FromVector4Destructive(this.Configuration, vectorSpan, rowSpan, this.modifiers);
                     }
                 });
         }
diff --git a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs
index 29e3ab5a9b..4abd698386 100644
--- a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs
@@ -28,7 +28,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         /// <param name="source">The source <see cref="Image{TPixel}"/> for the current processor instance.</param>
         /// <param name="sourceRectangle">The source area to process for the current processor instance.</param>
         public PixelShaderProcessor(PixelShaderProcessor definition, Image<TPixel> source, Rectangle sourceRectangle)
-            : base(source, sourceRectangle)
+            : base(definition.Modifiers, source, sourceRectangle)
         {
             this.pixelShader = definition.PixelShader;
         }
diff --git a/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor.cs b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor.cs
index a83e8b5a42..908f7472b7 100644
--- a/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor.cs
@@ -11,6 +11,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
     /// </summary>
     public sealed class PositionAwarePixelShaderProcessor : IImageProcessor
     {
+        /// <summary>
+        /// The default <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.
+        /// </summary>
+        public const PixelConversionModifiers DefaultModifiers = PixelConversionModifiers.None;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="PositionAwarePixelShaderProcessor"/> class.
         /// </summary>
@@ -20,6 +25,20 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         public PositionAwarePixelShaderProcessor(PositionAwarePixelShader pixelShader)
         {
             this.PixelShader = pixelShader;
+            this.Modifiers = DefaultModifiers;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PositionAwarePixelShaderProcessor"/> class.
+        /// </summary>
+        /// <param name="pixelShader">
+        /// The user defined pixel shader to use to modify images.
+        /// </param>
+        /// <param name="modifiers">The <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.</param>
+        public PositionAwarePixelShaderProcessor(PositionAwarePixelShader pixelShader, PixelConversionModifiers modifiers)
+        {
+            this.PixelShader = pixelShader;
+            this.Modifiers = modifiers;
         }
 
         /// <summary>
@@ -27,6 +46,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         /// </summary>
         public PositionAwarePixelShader PixelShader { get; }
 
+        /// <summary>
+        /// Gets the <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.
+        /// </summary>
+        public PixelConversionModifiers Modifiers { get; }
+
         /// <inheritdoc />
         public IImageProcessor<TPixel> CreatePixelSpecificProcessor<TPixel>(Image<TPixel> source, Rectangle sourceRectangle)
             where TPixel : struct, IPixel<TPixel>
diff --git a/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs
index 6c4eee35f5..3b9f37b485 100644
--- a/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs
@@ -28,7 +28,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         /// <param name="source">The source <see cref="Image{TPixel}"/> for the current processor instance.</param>
         /// <param name="sourceRectangle">The source area to process for the current processor instance.</param>
         public PositionAwarePixelShaderProcessor(PositionAwarePixelShaderProcessor definition, Image<TPixel> source, Rectangle sourceRectangle)
-            : base(source, sourceRectangle)
+            : base(definition.Modifiers, source, sourceRectangle)
         {
             this.pixelShader = definition.PixelShader;
         }

From ed02d3525a7f667871dcf0c20c8e5e165289eebb Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Thu, 26 Dec 2019 11:29:21 +0100
Subject: [PATCH 13/18] Added overloads with custom pixel modifiers in pixel
 shading extensions

---
 .../Extensions/PixelShaderExtensions.cs       | 47 +++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
index 30848e346c..b866e7fb14 100644
--- a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
+++ b/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing.Processors.Effects;
 using SixLabors.Primitives;
 
@@ -20,6 +21,16 @@ namespace SixLabors.ImageSharp.Processing
         public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PixelShader pixelShader)
             => source.ApplyProcessor(new PixelShaderProcessor(pixelShader));
 
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</param>
+        /// <param name="modifiers">The <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PixelShader pixelShader, PixelConversionModifiers modifiers)
+            => source.ApplyProcessor(new PixelShaderProcessor(pixelShader, modifiers));
+
         /// <summary>
         /// Applies a user defined pixel shader to the image.
         /// </summary>
@@ -32,6 +43,19 @@ namespace SixLabors.ImageSharp.Processing
         public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PixelShader pixelShader, Rectangle rectangle)
             => source.ApplyProcessor(new PixelShaderProcessor(pixelShader), rectangle);
 
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</param>
+        /// <param name="rectangle">
+        /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
+        /// </param>
+        /// <param name="modifiers">The <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PixelShader pixelShader, Rectangle rectangle, PixelConversionModifiers modifiers)
+            => source.ApplyProcessor(new PixelShaderProcessor(pixelShader, modifiers), rectangle);
+
         /// <summary>
         /// Applies a user defined pixel shader to the image.
         /// </summary>
@@ -41,6 +65,16 @@ namespace SixLabors.ImageSharp.Processing
         public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PositionAwarePixelShader pixelShader)
             => source.ApplyProcessor(new PositionAwarePixelShaderProcessor(pixelShader));
 
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</param>
+        /// <param name="modifiers">The <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PositionAwarePixelShader pixelShader, PixelConversionModifiers modifiers)
+            => source.ApplyProcessor(new PositionAwarePixelShaderProcessor(pixelShader, modifiers));
+
         /// <summary>
         /// Applies a user defined pixel shader to the image.
         /// </summary>
@@ -52,5 +86,18 @@ namespace SixLabors.ImageSharp.Processing
         /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
         public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PositionAwarePixelShader pixelShader, Rectangle rectangle)
             => source.ApplyProcessor(new PositionAwarePixelShaderProcessor(pixelShader), rectangle);
+
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</param>
+        /// <param name="rectangle">
+        /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
+        /// </param>
+        /// <param name="modifiers">The <see cref="PixelConversionModifiers"/> to apply during the pixel conversions.</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PositionAwarePixelShader pixelShader, Rectangle rectangle, PixelConversionModifiers modifiers)
+            => source.ApplyProcessor(new PositionAwarePixelShaderProcessor(pixelShader, modifiers), rectangle);
     }
 }

From e0cbe2fa0bcf702217a0c321374007f23b67c283 Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 3 Jan 2020 16:32:56 +0100
Subject: [PATCH 14/18] Added pixel shader tests

---
 .../Processors/Effects/PixelShaderTest.cs     | 53 +++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs

diff --git a/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs b/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs
new file mode 100644
index 0000000000..5da1e96a96
--- /dev/null
+++ b/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs
@@ -0,0 +1,53 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System.Numerics;
+
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing;
+
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
+{
+    [GroupOutput("Effects")]
+    public class PixelShaderTest
+    {
+        [Theory]
+        [WithFile(TestImages.Png.CalliphoraPartial, PixelTypes.Rgba32)]
+        public void FullImage<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            provider.RunValidatingProcessorTest(
+                x => x.ApplyPixelShaderProcessor(
+                span =>
+                {
+                    for (int i = 0; i < span.Length; i++)
+                    {
+                        Vector4 v4 = span[i];
+                        float avg = (v4.X + v4.Y + v4.Z) / 3f;
+                        span[i] = new Vector4(avg);
+                    }
+                }),
+                appendPixelTypeToFileName: false);
+        }
+
+        [Theory]
+        [WithFile(TestImages.Png.CalliphoraPartial, PixelTypes.Rgba32)]
+        public void InBox<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            provider.RunRectangleConstrainedValidatingProcessorTest(
+                (x, rect) => x.ApplyPixelShaderProcessor(
+                    span =>
+                    {
+                        for (int i = 0; i < span.Length; i++)
+                        {
+                            Vector4 v4 = span[i];
+                            float avg = (v4.X + v4.Y + v4.Z) / 3f;
+                            span[i] = new Vector4(avg);
+                        }
+                    }, rect));
+        }
+    }
+}

From 9dc1927697695d1f427a7015519a6e7fe4188f50 Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Fri, 3 Jan 2020 16:54:19 +0100
Subject: [PATCH 15/18] Added tests for convolution aware pixel shader

---
 .../Processors/Effects/PixelShaderTest.cs     | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs b/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs
index 5da1e96a96..d9af215b97 100644
--- a/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs
+++ b/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.Numerics;
 
 using SixLabors.ImageSharp.PixelFormats;
@@ -49,5 +50,60 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
                         }
                     }, rect));
         }
+
+        [Theory]
+        [WithFile(TestImages.Png.CalliphoraPartial, PixelTypes.Rgba32)]
+        public void PositionAwareFullImage<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            provider.RunValidatingProcessorTest(
+                c => c.ApplyPixelShaderProcessor(
+                    (span, y, x) =>
+                    {
+                        for (int i = 0; i < span.Length; i++)
+                        {
+                            float
+                                sine = MathF.Sin(y),
+                                cosine = MathF.Cos(x + i),
+                                sum = sine + cosine,
+                                abs = MathF.Abs(sum),
+                                a = 0.5f + abs / 2; // Max value for sin(y) + cos(x) is 2
+                                
+                            Vector4 v4 = span[i];
+                            float avg = (v4.X + v4.Y + v4.Z) / 3f;
+                            var gray = new Vector4(avg, avg, avg, a);
+
+                            span[i] = Vector4.Clamp(gray, Vector4.Zero, Vector4.One);
+                        }
+                    }),
+                appendPixelTypeToFileName: false);
+        }
+
+        [Theory]
+        [WithFile(TestImages.Png.CalliphoraPartial, PixelTypes.Rgba32)]
+        public void PositionAwareInBox<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            provider.RunRectangleConstrainedValidatingProcessorTest(
+                (c, rect) => c.ApplyPixelShaderProcessor(
+                    (span, y, x) =>
+                    {
+                        for (int i = 0; i < span.Length; i++)
+                        {
+                            float
+                                sine = MathF.Sin(y),
+                                cosine = MathF.Cos(x + i),
+                                sum = sine + cosine,
+                                abs = MathF.Abs(sum),
+                                a = 0.5f + abs / 2;
+
+                            Vector4 v4 = span[i];
+                            float avg = (v4.X + v4.Y + v4.Z) / 3f;
+                            var gray = new Vector4(avg, avg, avg, a);
+
+                            span[i] = Vector4.Clamp(gray, Vector4.Zero, Vector4.One);
+                        }
+                    }, rect));
+        }
     }
 }

From 0c0d2bba6d93d7802aaa86fdac27f01037eaafc1 Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Mon, 6 Jan 2020 02:55:28 +0100
Subject: [PATCH 16/18] Fixed lambda capturing this

---
 .../Processors/Effects/PixelShaderProcessorBase.cs          | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
index f1245ca510..d75d23a51f 100644
--- a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
@@ -40,6 +40,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         {
             var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
             int startX = interest.X;
+            Configuration configuration = this.Configuration;
+            PixelConversionModifiers modifiers = this.modifiers;
 
             ParallelHelper.IterateRowsWithTempBuffer<Vector4>(
                 interest,
@@ -51,12 +53,12 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
                         Span<Vector4> vectorSpan = vectorBuffer.Span;
                         int length = vectorSpan.Length;
                         Span<TPixel> rowSpan = source.GetPixelRowSpan(y).Slice(startX, length);
-                        PixelOperations<TPixel>.Instance.ToVector4(this.Configuration, rowSpan, vectorSpan, this.modifiers);
+                        PixelOperations<TPixel>.Instance.ToVector4(configuration, rowSpan, vectorSpan, modifiers);
 
                         // Run the user defined pixel shader on the current row of pixels
                         this.ApplyPixelShader(vectorSpan, y, startX);
 
-                        PixelOperations<TPixel>.Instance.FromVector4Destructive(this.Configuration, vectorSpan, rowSpan, this.modifiers);
+                        PixelOperations<TPixel>.Instance.FromVector4Destructive(configuration, vectorSpan, rowSpan, modifiers);
                     }
                 });
         }

From b12924e79016824076dd39b738089c14297e93a7 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Mon, 6 Jan 2020 15:42:59 +1100
Subject: [PATCH 17/18] Use Point for offset

---
 .../{ => Effects}/PixelShaderExtensions.cs         |  0
 .../Processing/PositionAwarePixelShader.cs         |  6 +++---
 .../Processors/Effects/PixelShaderProcessorBase.cs |  7 +++----
 .../Effects/PixelShaderProcessor{TPixel}.cs        |  4 ++--
 .../PositionAwarePixelShaderProcessor{TPixel}.cs   |  4 ++--
 .../Processors/Effects/PixelShaderTest.cs          | 14 +++++++++-----
 6 files changed, 19 insertions(+), 16 deletions(-)
 rename src/ImageSharp/Processing/Extensions/{ => Effects}/PixelShaderExtensions.cs (100%)

diff --git a/src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs b/src/ImageSharp/Processing/Extensions/Effects/PixelShaderExtensions.cs
similarity index 100%
rename from src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs
rename to src/ImageSharp/Processing/Extensions/Effects/PixelShaderExtensions.cs
diff --git a/src/ImageSharp/Processing/PositionAwarePixelShader.cs b/src/ImageSharp/Processing/PositionAwarePixelShader.cs
index 63e9246b41..1ae3ba295a 100644
--- a/src/ImageSharp/Processing/PositionAwarePixelShader.cs
+++ b/src/ImageSharp/Processing/PositionAwarePixelShader.cs
@@ -3,6 +3,7 @@
 
 using System;
 using System.Numerics;
+using SixLabors.Primitives;
 
 namespace SixLabors.ImageSharp.Processing
 {
@@ -10,8 +11,7 @@ namespace SixLabors.ImageSharp.Processing
     /// A <see langword="delegate"/> representing a user defined pixel shader.
     /// </summary>
     /// <param name="span">The target row of <see cref="Vector4"/> pixels to process.</param>
-    /// <param name="offsetY">The initial vertical offset for the input pixels to process.</param>
-    /// <param name="offsetX">The initial horizontal offset for the input pixels to process.</param>
+    /// <param name="offset">The initial horizontal and vertical offset for the input pixels to process.</param>
     /// <remarks>The <see cref="Vector4.X"/>, <see cref="Vector4.Y"/>, <see cref="Vector4.Z"/>, and <see cref="Vector4.W"/> fields map the RGBA channels respectively.</remarks>
-    public delegate void PositionAwarePixelShader(Span<Vector4> span, int offsetY, int offsetX);
+    public delegate void PositionAwarePixelShader(Span<Vector4> span, Point offset);
 }
diff --git a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
index d75d23a51f..d46a4cf320 100644
--- a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessorBase.cs
@@ -56,7 +56,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
                         PixelOperations<TPixel>.Instance.ToVector4(configuration, rowSpan, vectorSpan, modifiers);
 
                         // Run the user defined pixel shader on the current row of pixels
-                        this.ApplyPixelShader(vectorSpan, y, startX);
+                        this.ApplyPixelShader(vectorSpan, new Point(startX, y));
 
                         PixelOperations<TPixel>.Instance.FromVector4Destructive(configuration, vectorSpan, rowSpan, modifiers);
                     }
@@ -67,8 +67,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         /// Applies the current pixel shader effect on a target row of preprocessed pixels.
         /// </summary>
         /// <param name="span">The target row of <see cref="Vector4"/> pixels to process.</param>
-        /// <param name="offsetY">The initial vertical offset for the input pixels to process.</param>
-        /// <param name="offsetX">The initial horizontal offset for the input pixels to process.</param>
-        protected abstract void ApplyPixelShader(Span<Vector4> span, int offsetY, int offsetX);
+        /// <param name="offset">The initial horizontal and vertical offset for the input pixels to process.</param>
+        protected abstract void ApplyPixelShader(Span<Vector4> span, Point offset);
     }
 }
diff --git a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs
index 4abd698386..ce7b858a3e 100644
--- a/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PixelShaderProcessor{TPixel}.cs
@@ -13,7 +13,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
     /// Applies a user defined pixel shader effect through a given delegate.
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal class PixelShaderProcessor<TPixel> : PixelShaderProcessorBase<TPixel>
+    internal sealed class PixelShaderProcessor<TPixel> : PixelShaderProcessorBase<TPixel>
         where TPixel : struct, IPixel<TPixel>
     {
         /// <summary>
@@ -34,6 +34,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         }
 
         /// <inheritdoc/>
-        protected override void ApplyPixelShader(Span<Vector4> span, int offsetY, int offsetX) => this.pixelShader(span);
+        protected override void ApplyPixelShader(Span<Vector4> span, Point offset) => this.pixelShader(span);
     }
 }
diff --git a/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs
index 3b9f37b485..549dedac15 100644
--- a/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/PositionAwarePixelShaderProcessor{TPixel}.cs
@@ -13,7 +13,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
     /// Applies a user defined pixel shader effect through a given delegate.
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal class PositionAwarePixelShaderProcessor<TPixel> : PixelShaderProcessorBase<TPixel>
+    internal sealed class PositionAwarePixelShaderProcessor<TPixel> : PixelShaderProcessorBase<TPixel>
         where TPixel : struct, IPixel<TPixel>
     {
         /// <summary>
@@ -34,6 +34,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
         }
 
         /// <inheritdoc/>
-        protected override void ApplyPixelShader(Span<Vector4> span, int offsetY, int offsetX) => this.pixelShader(span, offsetY, offsetX);
+        protected override void ApplyPixelShader(Span<Vector4> span, Point offset) => this.pixelShader(span, offset);
     }
 }
diff --git a/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs b/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs
index d9af215b97..c18f043852 100644
--- a/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs
+++ b/tests/ImageSharp.Tests/Processing/Processors/Effects/PixelShaderTest.cs
@@ -58,8 +58,10 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
         {
             provider.RunValidatingProcessorTest(
                 c => c.ApplyPixelShaderProcessor(
-                    (span, y, x) =>
+                    (span, offset) =>
                     {
+                        int y = offset.Y;
+                        int x = offset.X;
                         for (int i = 0; i < span.Length; i++)
                         {
                             float
@@ -67,8 +69,8 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
                                 cosine = MathF.Cos(x + i),
                                 sum = sine + cosine,
                                 abs = MathF.Abs(sum),
-                                a = 0.5f + abs / 2; // Max value for sin(y) + cos(x) is 2
-                                
+                                a = 0.5f + (abs / 2); // Max value for sin(y) + cos(x) is 2
+
                             Vector4 v4 = span[i];
                             float avg = (v4.X + v4.Y + v4.Z) / 3f;
                             var gray = new Vector4(avg, avg, avg, a);
@@ -86,8 +88,10 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
         {
             provider.RunRectangleConstrainedValidatingProcessorTest(
                 (c, rect) => c.ApplyPixelShaderProcessor(
-                    (span, y, x) =>
+                    (span, offset) =>
                     {
+                        int y = offset.Y;
+                        int x = offset.X;
                         for (int i = 0; i < span.Length; i++)
                         {
                             float
@@ -95,7 +99,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Effects
                                 cosine = MathF.Cos(x + i),
                                 sum = sine + cosine,
                                 abs = MathF.Abs(sum),
-                                a = 0.5f + abs / 2;
+                                a = 0.5f + (abs / 2);
 
                             Vector4 v4 = span[i];
                             float avg = (v4.X + v4.Y + v4.Z) / 3f;

From 620cf0edcd9b8f6486c90757df824a881a9e2677 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Mon, 6 Jan 2020 15:45:03 +1100
Subject: [PATCH 18/18] Update reference images

---
 tests/Images/External | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/Images/External b/tests/Images/External
index d7c099cebd..d8ea82085a 160000
--- a/tests/Images/External
+++ b/tests/Images/External
@@ -1 +1 @@
-Subproject commit d7c099cebd58f1d3ff997383351d52d28a29df3d
+Subproject commit d8ea82085ac39a6aa6ca8e0806a9518d3a7d3337