Improving convolution filter speed with Parallel.For

TODO: Check this again and expand to other methods

Former-commit-id: d1e608bee96e75c26c0665518374f4db5af8e899
Former-commit-id: a43b63910def35dc41b4b5a494d00f7c9089e398

src/ImageProcessor.Playground/Program.cs

@@ -77,9 +77,9 @@ namespace ImageProcessor.PlayGround
                             //.ReplaceColor(Color.FromArgb(255, 1, 107, 165), Color.FromArgb(255, 1, 165, 13), 80)
                             //.Resize(layer)
                             //.DetectEdges(new KirschEdgeFilter())
-                            //.DetectEdges(new LaplacianOfGaussianFilter())
+                            .DetectEdges(new LaplacianOfGaussianEdgeFilter())
                             //.EntropyCrop()
-                            .Filter(MatrixFilters.Comic)
+                            //.Filter(MatrixFilters.Comic)
                             //.Filter(MatrixFilters.Comic)
                             //.Filter(MatrixFilters.HiSatch)
                             //.Pixelate(8)

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

@@ -13,6 +13,7 @@ namespace ImageProcessor.Imaging.Filters.EdgeDetection
     using System;
     using System.Drawing;
     using System.Drawing.Imaging;
+    using System.Threading.Tasks;
 
     using ImageProcessor.Common.Extensions;
     using ImageProcessor.Imaging.Filters.Photo;
@@ -92,7 +93,10 @@ 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++)
                                 {
@@ -131,6 +135,7 @@ 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;
@@ -151,9 +156,10 @@ namespace ImageProcessor.Imaging.Filters.EdgeDetection
                                     byte blue = bX.ToByte();
 
                                     Color newColor = Color.FromArgb(red, green, blue);
+                                    // ReSharper disable once AccessToDisposedClosure
                                     destinationBitmap.SetPixel(x, y, newColor);
                                 }
-                        }
+                            });
                     }
                 }
             }