More speed improvements

Former-commit-id: b2e663bca1492bf9e28a1da8051731646a19feef
Former-commit-id: ec08860c20b0eb2e8423d834b3548fd939d90a76

src/ImageProcessor.Playground/images/input/circle3.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:7f6f6f0e7876609f12e7549a4fb605102e62027661a1fe93bbffad96ec5e5731
+size 5322

src/ImageProcessor/Imaging/Convolution.cs

@@ -12,6 +12,7 @@ namespace ImageProcessor.Imaging
 {
     using System;
     using System.Drawing;
+    using System.Threading.Tasks;
 
     using ImageProcessor.Common.Extensions;
 
@@ -274,7 +275,10 @@ namespace ImageProcessor.Imaging
                     int threshold = this.Threshold;
 
                     // For each line
-                    for (int y = 0; y < height; y++)
+                    Parallel.For(
+                        0,
+                        height,
+                        y =>
                         {
                             // For each pixel
                             for (int x = 0; x < width; x++)
@@ -321,6 +325,7 @@ namespace ImageProcessor.Imaging
 
                                         if (offsetX < width)
                                         {
+                                            // ReSharper disable once AccessToDisposedClosure
                                             Color color = sourceFastBitmap.GetPixel(offsetX, offsetY);
                                             double k = kernel[i, j];
                                             divider += k;
@@ -366,9 +371,10 @@ namespace ImageProcessor.Imaging
                                 blue += threshold;
                                 alpha += threshold;
 
+                                // ReSharper disable once AccessToDisposedClosure
                                 destinationFastBitmap.SetPixel(x, y, Color.FromArgb(alpha.ToByte(), red.ToByte(), green.ToByte(), blue.ToByte()));
                             }
-                    }
+                        });
                 }
             }
 

src/ImageProcessor/Imaging/FastBitmap.cs

@@ -156,6 +156,7 @@ namespace ImageProcessor.Imaging
         /// <returns>The <see cref="System.Drawing.Color"/> at the given pixel.</returns>
         public Color GetPixel(int x, int y)
         {
+#if DEBUG
             if ((x < 0) || (x >= this.width))
             {
                 throw new ArgumentOutOfRangeException("x", "Value cannot be less than zero or greater than the bitmap width.");
@@ -165,7 +166,7 @@ namespace ImageProcessor.Imaging
             {
                 throw new ArgumentOutOfRangeException("y", "Value cannot be less than zero or greater than the bitmap height.");
             }
-
+#endif
             PixelData* data = this[x, y];
             return Color.FromArgb(data->A, data->R, data->G, data->B);
         }
@@ -181,6 +182,7 @@ namespace ImageProcessor.Imaging
         /// </param>
         public void SetPixel(int x, int y, Color color)
         {
+#if DEBUG
             if ((x < 0) || (x >= this.width))
             {
                 throw new ArgumentOutOfRangeException("x", "Value cannot be less than zero or greater than the bitmap width.");
@@ -190,7 +192,7 @@ namespace ImageProcessor.Imaging
             {
                 throw new ArgumentOutOfRangeException("y", "Value cannot be less than zero or greater than the bitmap height.");
             }
-
+#endif
             PixelData* data = this[x, y];
             data->R = color.R;
             data->G = color.G;

src/ImageProcessor/Imaging/Filters/Binarization/BinaryThreshold.cs

@@ -11,6 +11,10 @@
 namespace ImageProcessor.Imaging.Filters.Binarization
 {
     using System.Drawing;
+    using System.Drawing.Imaging;
+    using System.Threading.Tasks;
+
+    using ImageProcessor.Imaging.Filters.Photo;
 
     /// <summary>
     /// Performs binary threshold filtering against a given greyscale image.
@@ -20,7 +24,7 @@ namespace ImageProcessor.Imaging.Filters.Binarization
         /// <summary>
         /// The threshold value.
         /// </summary>
-        private byte threshold = 128;
+        private byte threshold = 10;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="BinaryThreshold"/> class.
@@ -61,14 +65,19 @@ namespace ImageProcessor.Imaging.Filters.Binarization
 
             using (FastBitmap sourceBitmap = new FastBitmap(source))
             {
-                for (int y = 0; y < height; y++)
+                Parallel.For(
+                    0,
+                    height,
+                    y =>
                     {
                         for (int x = 0; x < width; x++)
                         {
+                            // ReSharper disable AccessToDisposedClosure
                             Color color = sourceBitmap.GetPixel(x, y);
                             sourceBitmap.SetPixel(x, y, color.B >= this.threshold ? Color.White : Color.Black);
+                            // ReSharper restore AccessToDisposedClosure
                         }
-                }
+                    });
             }
 
             return source;

src/ImageProcessor/Imaging/Filters/EdgeDetection/ConvolutionFilter.cs

@@ -49,7 +49,7 @@ namespace ImageProcessor.Imaging.Filters.EdgeDetection
         }
 
         /// <summary>
-        /// Processes the given bitmap to apply the current instances <see cref="IEdgeFilter"/>.
+        /// Processes the given bitmap to apply the current instance of <see cref="IEdgeFilter"/>.
         /// </summary>
         /// <param name="source">The image to process.</param>
         /// <returns>A processed bitmap.</returns>
@@ -184,7 +184,7 @@ namespace ImageProcessor.Imaging.Filters.EdgeDetection
         }
 
         /// <summary>
-        /// Processes the given bitmap to apply the current instances <see cref="IEdgeFilter"/>.
+        /// Processes the given bitmap to apply the current instance of <see cref="I2DEdgeFilter"/>.
         /// </summary>
         /// <param name="source">The image to process.</param>
         /// <returns>A processed bitmap.</returns>
@@ -229,7 +229,10 @@ namespace ImageProcessor.Imaging.Filters.EdgeDetection
                     using (FastBitmap destinationBitmap = new FastBitmap(destination))
                     {
                         // Loop through the pixels.
-                        for (int y = 0; y < height; y++)
+                        Parallel.For(
+                            0,
+                            height,
+                            y =>
                             {
                                 for (int x = 0; x < width; x++)
                                 {
@@ -271,6 +274,7 @@ namespace ImageProcessor.Imaging.Filters.EdgeDetection
 
                                             if (offsetX < width)
                                             {
+                                                // ReSharper disable once AccessToDisposedClosure
                                                 Color currentColor = sourceBitmap.GetPixel(offsetX, offsetY);
                                                 double r = currentColor.R;
                                                 double g = currentColor.G;
@@ -294,9 +298,10 @@ namespace ImageProcessor.Imaging.Filters.EdgeDetection
                                     byte blue = Math.Sqrt((bX * bX) + (bY * bY)).ToByte();
 
                                     Color newColor = Color.FromArgb(red, green, blue);
+                                    // ReSharper disable once AccessToDisposedClosure
                                     destinationBitmap.SetPixel(x, y, newColor);
                                 }
-                        }
+                            });
                     }
                 }
             }

src/ImageProcessor/Processors/EntropyCrop.cs

@@ -11,6 +11,7 @@ namespace ImageProcessor.Processors
     using System.Collections.Generic;
     using System.Drawing;
     using System.Drawing.Imaging;
+    using System.IO;
 
     using ImageProcessor.Common.Exceptions;
     using ImageProcessor.Imaging;
@@ -59,7 +60,8 @@ namespace ImageProcessor.Processors
 
             try
             {
-                grey = new ConvolutionFilter(new SobelEdgeFilter(), true).ProcessFilter((Bitmap)image);
+                // Detect the edges then strip out middle shades.
+                grey = new ConvolutionFilter(new SobelEdgeFilter(), true).Process2DFilter((Bitmap)image);
                 grey = new BinaryThreshold(threshold).ProcessFilter(grey);
                 
                 Rectangle rectangle = this.FindBoundingBox(grey, 0);