First rough filter API attempt

Former-commit-id: e355d9dc0b3efaee0c8c54435090041dac447c45
Former-commit-id: 7ef69bb6c4f28b1e6ae704d84963c4aa7bd53073
Former-commit-id: 6a152f3985346d0b61a2f654f7eebbda8f46f265

src/ImageProcessor/Filters/Contrast.cs

@@ -0,0 +1,70 @@
+// <copyright file="Contrast.cs" company="James South">
+// Copyright © James South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessor.Filters
+{
+    using System;
+
+    /// <summary>
+    /// An <see cref="IImageFilter"/> to change the contrast of an <see cref="Image"/>.
+    /// </summary>
+    public class Contrast : ParallelImageFilter
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Contrast"/> class.
+        /// </summary>
+        /// <param name="contrast">The new contrast of the image. Must be between -100 and 100.</param>
+        /// <exception cref="ArgumentException">
+        /// <paramref name="contrast"/> is less than -100 is greater than 100.
+        /// </exception>
+        public Contrast(int contrast)
+        {
+            Guard.MustBeBetweenOrEqualTo(contrast, -100, 100, nameof(contrast));
+            this.Value = contrast;
+        }
+
+        /// <summary>
+        /// Gets the contrast value.
+        /// </summary>
+        public int Value { get; }
+
+        /// <inheritdoc/>
+        protected override void Apply(ImageBase target, ImageBase source, Rectangle rectangle, int startY, int endY)
+        {
+            double contrast = (100.0 + this.Value) / 100.0;
+
+            for (int y = startY; y < endY; y++)
+            {
+                for (int x = rectangle.X; x < rectangle.Right; x++)
+                {
+                    Bgra color = source[x, y];
+
+                    double r = color.R / 255.0;
+                    r -= 0.5;
+                    r *= contrast;
+                    r += 0.5;
+                    r *= 255;
+                    r = r.Clamp(0, 255);
+
+                    double g = color.G / 255.0;
+                    g -= 0.5;
+                    g *= contrast;
+                    g += 0.5;
+                    g *= 255;
+                    g = g.Clamp(0, 255);
+
+                    double b = color.B / 255.0;
+                    b -= 0.5;
+                    b *= contrast;
+                    b += 0.5;
+                    b *= 255;
+                    b = b.Clamp(0, 255);
+
+                    target[x, y] = new Bgra((byte)b, (byte)g, (byte)r, color.A);
+                }
+            }
+        }
+    }
+}

src/ImageProcessor/Filters/IImageFilter.cs

@@ -0,0 +1,34 @@
+namespace ImageProcessor.Filters
+{
+    /// <summary>
+    /// Image processing filter interface.
+    /// </summary>
+    /// <remarks>
+    /// The interface defines the set of methods, which should be
+    /// provided by all image processing filters. Methods of this interface
+    /// manipulate the original image.
+    /// </remarks>
+    public interface IImageFilter
+    {
+        /// <summary>
+        /// Apply filter to an image at the area of the specified rectangle.
+        /// </summary>
+        /// <param name="target">Target image to apply filter to.</param>
+        /// <param name="source">The source image. Cannot be null.</param>
+        /// <param name="rectangle">The rectangle, which defines the area of the
+        /// image where the filter should be applied to.</param>
+        /// <remarks>The method keeps the source image unchanged and returns the
+        /// the result of image processing filter as new image.</remarks>
+        /// <exception cref="System.ArgumentNullException">
+        ///     <paramref name="target"/>
+        ///     is null.
+        ///     - or -
+        ///     <paramref name="source"/>
+        ///     is null.
+        /// </exception>
+        /// <exception cref="System.ArgumentException">
+        /// <paramref name="rectangle"/> doesnt fit the dimension of the image.
+        /// </exception>
+        void Apply(ImageBase target, ImageBase source, Rectangle rectangle);
+    }
+}

src/ImageProcessor/Filters/ImageFilterExtensions.cs

@@ -0,0 +1,81 @@
+// <copyright file="ImageFilterExtensions.cs" company="James South">
+// Copyright © James South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessor.Filters
+{
+    using System;
+
+    /// <summary>
+    /// Exstension methods for performing filtering methods again an image.
+    /// </summary>
+    public static class ImageFilterExtensions
+    {
+        /// <summary>
+        /// Applies the collection of filters to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="filters">Any filters to apply to the image.</param>
+        /// <returns>The <see cref="Image"/>.</returns>
+        public static Image Filter(this Image source, params IImageFilter[] filters) => Filter(source, source.Bounds, filters);
+
+        /// <summary>
+        /// Applies the collection of filters to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="rectangle">
+        /// The rectangle defining the bounds of the pixels the image filter with adjust.</param>
+        /// <param name="filters">Any filters to apply to the image.</param>
+        /// <returns>The <see cref="Image"/>.</returns>
+        public static Image Filter(this Image source, Rectangle rectangle, params IImageFilter[] filters)
+        {
+            // ReSharper disable once LoopCanBeConvertedToQuery
+            foreach (IImageFilter filter in filters)
+            {
+                source = PerformAction(source, true, (sourceImage, targetImage) => filter.Apply(targetImage, sourceImage, rectangle));
+            }
+
+            return source;
+        }
+
+        /// <summary>
+        /// Alters the contrast component of the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="amount">The new contrast of the image. Must be between -100 and 100.</param>
+        /// <returns>The <see cref="Image"/>.</returns>
+        public static Image Contrast(this Image source, int amount) => source.Filter(new Contrast(amount));
+
+        /// <summary>
+        /// Performs the given action on the source image.
+        /// </summary>
+        /// <param name="source">The image to perform the action against.</param>
+        /// <param name="clone">Whether to clone the image.</param>
+        /// <param name="action">The <see cref="Action"/> to perform against the image.</param>
+        /// <returns>The <see cref="Image"/>.</returns>
+        private static Image PerformAction(Image source, bool clone, Action<ImageBase, ImageBase> action)
+        {
+            Image transformedImage = clone ? new Image(source) : new Image(source.Width, source.Height);
+            action(source, transformedImage);
+
+            for (int i = 0; i < source.Frames.Count; i++)
+            {
+                ImageFrame frame = source.Frames[i];
+                ImageFrame tranformedFrame = new ImageFrame(frame);
+                action(frame, tranformedFrame);
+
+                if (!clone)
+                {
+                    transformedImage.Frames.Add(tranformedFrame);
+                }
+                else
+                {
+                    transformedImage.Frames[i] = tranformedFrame;
+                }
+            }
+
+            return transformedImage;
+        }
+    }
+}

src/ImageProcessor/Filters/ParallelImageFilter.cs

@@ -0,0 +1,57 @@
+namespace ImageProcessor.Filters
+{
+    using System;
+    using System.Threading.Tasks;
+
+    /// <summary>
+    /// Allows the application of filters using prallel processing.
+    /// </summary>
+    public abstract class ParallelImageFilter : IImageFilter
+    {
+        /// <summary>
+        /// Gets or sets the count of workers to run the filter in parallel.
+        /// </summary>
+        public int Parallelism { get; set; } = Environment.ProcessorCount;
+
+        /// <inheritdoc/>
+        public void Apply(ImageBase target, ImageBase source, Rectangle rectangle)
+        {
+            this.OnApply();
+
+            if (this.Parallelism > 1)
+            {
+                int partitionCount = this.Parallelism;
+
+                Task[] tasks = new Task[partitionCount];
+
+                for (int p = 0; p < partitionCount; p++)
+                {
+                    int current = p;
+                    tasks[p] = Task.Run(() =>
+                    {
+                        int batchSize = rectangle.Height / partitionCount;
+                        int yStart = rectangle.Y + (current * batchSize);
+                        int yEnd = current == partitionCount - 1 ? rectangle.Bottom : yStart + batchSize;
+
+                        this.Apply(target, source, rectangle, yStart, yEnd);
+                    });
+                }
+
+                Task.WaitAll(tasks);
+            }
+            else
+            {
+                this.Apply(target, source, rectangle, rectangle.Y, rectangle.Bottom);
+            }
+        }
+
+        /// <summary>
+        /// This method is called before the filter is applied to prepare the filter.
+        /// </summary>
+        protected virtual void OnApply()
+        {
+        }
+
+        protected abstract void Apply(ImageBase target, ImageBase source, Rectangle rectangle, int startY, int endY);
+    }
+}

src/ImageProcessor/Formats/Jpg/JpegDecoder.cs

@@ -1,12 +1,7 @@
-// --------------------------------------------------------------------------------------------------------------------
+// <copyright file="JpegDecoder.cs" company="James South">
-// <copyright file="JpegEncoder.cs" company="James South">
+// Copyright © James South and contributors.
-//   Copyright © James South and contributors.
+// Licensed under the Apache License, Version 2.0.
-//   Licensed under the Apache License, Version 2.0.
 // </copyright>
-// <summary>
-//   Image decoder for generating an image out of a jpg stream.
-// </summary>
-// --------------------------------------------------------------------------------------------------------------------
 
 namespace ImageProcessor.Formats
 {
@@ -42,7 +37,11 @@ namespace ImageProcessor.Formats
         {
             Guard.NotNullOrEmpty(extension, "extension");
 
-            if (extension.StartsWith(".")) extension = extension.Substring(1);
+            if (extension.StartsWith("."))
+            {
+                extension = extension.Substring(1);
+            }
+
             return extension.Equals("JPG", StringComparison.OrdinalIgnoreCase) ||
                    extension.Equals("JPEG", StringComparison.OrdinalIgnoreCase) ||
                    extension.Equals("JFIF", StringComparison.OrdinalIgnoreCase);
@@ -68,7 +67,7 @@ namespace ImageProcessor.Formats
             if (header.Length >= 11)
             {
                 bool isJpeg = IsJpeg(header);
-                bool isExif = IsExif(header);
+                bool isExif = this.IsExif(header);
 
                 isSupported = isJpeg || isExif;
             }
@@ -76,30 +75,6 @@ namespace ImageProcessor.Formats
             return isSupported;
         }
 
-        private bool IsExif(byte[] header)
-        {
-            bool isExif =
-                header[6] == 0x45 && // E
-                header[7] == 0x78 && // x
-                header[8] == 0x69 && // i
-                header[9] == 0x66 && // f
-                header[10] == 0x00;
-
-            return isExif;
-        }
-
-        private static bool IsJpeg(byte[] header)
-        {
-            bool isJpg =
-                header[6] == 0x4A && // J
-                header[7] == 0x46 && // F
-                header[8] == 0x49 && // I
-                header[9] == 0x46 && // F
-                header[10] == 0x00;
-
-            return isJpg;
-        }
-
         /// <summary>
         /// Decodes the image from the specified stream and sets
         /// the data to image.
@@ -137,7 +112,7 @@ namespace ImageProcessor.Formats
                 {
                     Sample sample = row.GetAt(x);
 
-                    int offset = (y * pixelWidth + x) * 4;
+                    int offset = ((y * pixelWidth) + x) * 4;
 
                     pixels[offset + 0] = (byte)sample[2];
                     pixels[offset + 1] = (byte)sample[1];
@@ -148,5 +123,34 @@ namespace ImageProcessor.Formats
 
             image.SetPixels(pixelWidth, pixelHeight, pixels);
         }
+
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <param name="header"></param>
+        /// <returns></returns>
+        private bool IsExif(byte[] header)
+        {
+            bool isExif =
+                header[6] == 0x45 && // E
+                header[7] == 0x78 && // x
+                header[8] == 0x69 && // i
+                header[9] == 0x66 && // f
+                header[10] == 0x00;
+
+            return isExif;
+        }
+
+        private static bool IsJpeg(byte[] header)
+        {
+            bool isJpg =
+                header[6] == 0x4A && // J
+                header[7] == 0x46 && // F
+                header[8] == 0x49 && // I
+                header[9] == 0x46 && // F
+                header[10] == 0x00;
+
+            return isJpg;
+        }
     }
 }

src/ImageProcessor/Image.cs

@@ -61,6 +61,7 @@ namespace ImageProcessor
         {
             this.HorizontalResolution = DefaultHorizontalResolution;
             this.VerticalResolution = DefaultVerticalResolution;
+            this.CurrentImageFormat = DefaultFormats.Value.First(f => f.GetType() == typeof(PngFormat));
         }
 
         /// <summary>
@@ -74,6 +75,7 @@ namespace ImageProcessor
         {
             this.HorizontalResolution = DefaultHorizontalResolution;
             this.VerticalResolution = DefaultVerticalResolution;
+            this.CurrentImageFormat = DefaultFormats.Value.First(f => f.GetType() == typeof(PngFormat));
         }
 
         /// <summary>
@@ -97,6 +99,7 @@ namespace ImageProcessor
 
             this.HorizontalResolution = DefaultHorizontalResolution;
             this.VerticalResolution = DefaultVerticalResolution;
+            this.CurrentImageFormat = other.CurrentImageFormat;
         }
 
         /// <summary>

src/ImageProcessor/ImageProcessor.csproj

@@ -38,9 +38,12 @@
   </PropertyGroup>
   <ItemGroup>
     <!-- A reference to the entire .NET Framework is automatically included -->
-    <Folder Include="Filters\Transforms\" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Filters\Contrast.cs" />
+    <Compile Include="Filters\ImageFilterExtensions.cs" />
+    <Compile Include="Filters\ParallelImageFilter.cs" />
+    <Compile Include="Filters\IImageFilter.cs" />
     <Compile Include="Colors\Hsv.cs" />
     <Compile Include="Colors\YCbCr.cs" />
     <Compile Include="Common\Extensions\ByteExtensions.cs" />
@@ -174,6 +177,7 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Numerics\Rectangle.cs" />
     <Compile Include="Numerics\Size.cs" />
+    <Compile Include="Samplers\IImageSampler.cs" />
   </ItemGroup>
   <ItemGroup>
     <Reference Include="ICSharpCode.SharpZipLib.Portable, Version=0.86.0.51802, Culture=neutral, processorArchitecture=MSIL">

src/ImageProcessor/Samplers/IImageSampler.cs

@@ -0,0 +1,23 @@
+// <copyright file="IImageSampler.cs" company="James South">
+// Copyright © James South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessor.Samplers
+{
+    /// <summary>
+    /// Encapsulates the methods required for all image sampling (resizing) algorithms.
+    /// </summary>
+    public interface IImageSampler
+    {
+        /// <summary>
+        /// Resizes the specified source image by creating a new image with
+        /// the specified size which is a resized version of the passed image.
+        /// </summary>
+        /// <param name="source">The source image.</param>
+        /// <param name="target">The target image.</param>
+        /// <param name="width">The width.</param>
+        /// <param name="height">The height.</param>
+        void Sample(ImageBase source, ImageBase target, int width, int height);
+    }
+}

tests/ImageProcessor.Tests/Filters/FilterTests.cs

@@ -0,0 +1,58 @@
+
+namespace ImageProcessor.Tests.Filters
+{
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.IO;
+
+    using ImageProcessor.Filters;
+
+    using Xunit;
+
+    public class FilterTests
+    {
+        public static readonly List<string> Files = new List<string>
+        {
+            { "../../TestImages/Formats/Jpg/Backdrop.jpg"},
+            { "../../TestImages/Formats/Bmp/Car.bmp" },
+            { "../../TestImages/Formats/Png/cmyk.png" },
+            //{ "../../TestImages/Formats/Gif/a.gif" },
+            //{ "../../TestImages/Formats/Gif/leaf.gif" },
+            //{ "../../TestImages/Formats/Gif/ani.gif" },
+            //{ "../../TestImages/Formats/Gif/ani2.gif" },
+            //{ "../../TestImages/Formats/Gif/giphy.gif" },
+        };
+
+        public static readonly TheoryData<string, IImageFilter> Filters = new TheoryData<string, IImageFilter>
+        {
+            { "Contrast-50", new Contrast(50) },
+            { "Contrast--50", new Contrast(-50) },
+        };
+
+        [Theory]
+        [MemberData("Filters")]
+        public void FilterImage(string name, IImageFilter filter)
+        {
+            if (!Directory.Exists("Filtered"))
+            {
+                Directory.CreateDirectory("Filtered");
+            }
+
+            foreach (string file in Files)
+            {
+                using (FileStream stream = File.OpenRead(file))
+                {
+                    Stopwatch watch = Stopwatch.StartNew();
+                    Image image = new Image(stream);
+                    string filename = Path.GetFileNameWithoutExtension(file) + "-" + name + Path.GetExtension(file);
+                    using (FileStream output = File.OpenWrite($"Filtered/{ Path.GetFileName(filename) }"))
+                    {
+                        image.Filter(filter).Save(output);
+                    }
+
+                    Trace.WriteLine($"{ name }: { watch.ElapsedMilliseconds}ms");
+                }
+            }
+        }
+    }
+}

tests/ImageProcessor.Tests/Formats/EncoderDecoderTests.cs

@@ -2,9 +2,8 @@
 {
     using System.Diagnostics;
     using System.IO;
-    using System.Linq;
 
-    using ImageProcessor.Formats;
+    using Formats;
 
     using Xunit;
 

tests/ImageProcessor.Tests/ImageProcessor.Tests.csproj

@@ -53,6 +53,7 @@
   <ItemGroup>
     <Compile Include="Colors\ColorConversionTests.cs" />
     <Compile Include="Colors\ColorTests.cs" />
+    <Compile Include="Filters\FilterTests.cs" />
     <Compile Include="Formats\EncoderDecoderTests.cs" />
     <Compile Include="Helpers\GuardTests.cs" />
     <Compile Include="Numerics\RectangleTests.cs" />