From c4e8bb2827091e50824d360589579478df7ed5aa Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Fri, 29 Jul 2016 10:35:10 +1000
Subject: [PATCH] Greyscale

Former-commit-id: ccc16cc88844e4cd046130b7f9366937ae10d48a
Former-commit-id: 0859791c265f40f2a1dc6e3d1e5c3e05a8726414
Former-commit-id: 6fe4767553f7f3776e7116f9c0b1eb1c63be0eae
---
 src/ImageProcessorCore/Filters/Greyscale.cs   | 63 +++++++++++++++++++
 .../Processors/Filters/GreyscaleTest.cs       | 48 ++++++++++++++
 2 files changed, 111 insertions(+)
 create mode 100644 src/ImageProcessorCore/Filters/Greyscale.cs
 create mode 100644 tests/ImageProcessorCore.Tests/Processors/Filters/GreyscaleTest.cs

diff --git a/src/ImageProcessorCore/Filters/Greyscale.cs b/src/ImageProcessorCore/Filters/Greyscale.cs
new file mode 100644
index 000000000..90db30554
--- /dev/null
+++ b/src/ImageProcessorCore/Filters/Greyscale.cs
@@ -0,0 +1,63 @@
+// <copyright file="Greyscale.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessorCore
+{
+    using Processors;
+
+    /// <summary>
+    /// Extension methods for the <see cref="Image{T,TP}"/> type.
+    /// </summary>
+    public static partial class ImageExtensions
+    {
+        /// <summary>
+        /// Applies greyscale toning to the image.
+        /// </summary>
+        /// <typeparam name="T">The pixel format.</typeparam>
+        /// <typeparam name="TP">The packed format. <example>long, float.</example></typeparam>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="mode">The formula to apply to perform the operation.</param>
+        /// <param name="progressHandler">A delegate which is called as progress is made processing the image.</param>
+        /// <returns>The <see cref="Image{T,TP}"/>.</returns>
+        public static Image<T, TP> Greyscale<T, TP>(this Image<T, TP> source, GreyscaleMode mode = GreyscaleMode.Bt709, ProgressEventHandler progressHandler = null)
+            where T : IPackedVector<TP>
+            where TP : struct
+        {
+            return Greyscale(source, source.Bounds, mode, progressHandler);
+        }
+
+        /// <summary>
+        /// Applies greyscale toning to the image.
+        /// </summary>
+        /// <typeparam name="T">The pixel format.</typeparam>
+        /// <typeparam name="TP">The packed format. <example>long, float.</example></typeparam>
+        /// <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="mode">The formula to apply to perform the operation.</param>
+        /// <param name="progressHandler">A delegate which is called as progress is made processing the image.</param>
+        /// <returns>The <see cref="Image{T,TP}"/>.</returns>
+        public static Image<T, TP> Greyscale<T, TP>(this Image<T, TP> source, Rectangle rectangle, GreyscaleMode mode = GreyscaleMode.Bt709, ProgressEventHandler progressHandler = null)
+            where T : IPackedVector<TP>
+            where TP : struct
+        {
+            IImageProcessor<T, TP> processor = mode == GreyscaleMode.Bt709
+                ? (IImageProcessor<T, TP>)new GreyscaleBt709Processor<T, TP>()
+                : new GreyscaleBt601Processor<T, TP>();
+
+            processor.OnProgress += progressHandler;
+
+            try
+            {
+                return source.Process(rectangle, processor);
+            }
+            finally
+            {
+                processor.OnProgress -= progressHandler;
+            }
+        }
+    }
+}
diff --git a/tests/ImageProcessorCore.Tests/Processors/Filters/GreyscaleTest.cs b/tests/ImageProcessorCore.Tests/Processors/Filters/GreyscaleTest.cs
new file mode 100644
index 000000000..427cc346a
--- /dev/null
+++ b/tests/ImageProcessorCore.Tests/Processors/Filters/GreyscaleTest.cs
@@ -0,0 +1,48 @@
+// <copyright file="GreyscaleTest.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessorCore.Tests
+{
+    using Processors;
+    using System.IO;
+
+    using Xunit;
+
+    public class GreyscaleTest : FileTestBase
+    {
+        public static readonly TheoryData<GreyscaleMode> GreyscaleValues
+        = new TheoryData<GreyscaleMode>
+        {
+            GreyscaleMode.Bt709 ,
+            GreyscaleMode.Bt601 ,
+        };
+
+        [Theory]
+        [MemberData("GreyscaleValues")]
+        public void ImageShouldApplyGreyscaleFilter(GreyscaleMode value)
+        {
+            const string path = "TestOutput/Greyscale";
+            if (!Directory.Exists(path))
+            {
+                Directory.CreateDirectory(path);
+            }
+
+            foreach (string file in Files)
+            {
+                using (FileStream stream = File.OpenRead(file))
+                {
+                    string filename = Path.GetFileNameWithoutExtension(file) + "-" + value + Path.GetExtension(file);
+
+                    Image image = new Image(stream);
+                    using (FileStream output = File.OpenWrite($"{path}/{filename}"))
+                    {
+                        image.Greyscale(value)
+                             .Save(output);
+                    }
+                }
+            }
+        }
+    }
+}
\ No newline at end of file