Attempted fix for transparency palette

Former-commit-id: e3e3fc74b8fe73b1e0c27ef4aaa343a82e54e2b9
Former-commit-id: 16dde1e9798765762fa9314cd77e210081d2dd0a

src/ImageProcessor.Playground/Program.cs

@@ -50,12 +50,12 @@ namespace ImageProcessor.PlayGround
             }
 
             // Image mask = Image.FromFile(Path.Combine(resolvedPath, "mask2.png"));
-            FileInfo fileInfo = new FileInfo(Path.Combine(resolvedPath, "rgba.png"));
-            //IEnumerable<FileInfo> files = GetFilesByExtensions(di, ".png");
+            //FileInfo fileInfo = new FileInfo(Path.Combine(resolvedPath, "effect_24bit.png"));
+            IEnumerable<FileInfo> files = GetFilesByExtensions(di, ".png");
             //IEnumerable<FileInfo> files = GetFilesByExtensions(di, ".gif", ".webp", ".bmp", ".jpg", ".png", ".tif");
 
-            //foreach (FileInfo fileInfo in files)
-            //{
+            foreach (FileInfo fileInfo in files)
+            {
                 byte[] photoBytes = File.ReadAllBytes(fileInfo.FullName);
                 Console.WriteLine("Processing: " + fileInfo.Name);
 
@@ -94,7 +94,7 @@ namespace ImageProcessor.PlayGround
                             //.EntropyCrop()
                             //.Filter(MatrixFilters.Invert)
                             //.Contrast(50)
-                            //.Filter(MatrixFilters.Comic)
+                            .Filter(MatrixFilters.Comic)
                             //.Flip()
                             //.Filter(MatrixFilters.HiSatch)
                             //.Pixelate(8)
@@ -109,7 +109,7 @@ namespace ImageProcessor.PlayGround
                 Console.WriteLine(@"Completed {0} in {1:s\.fff} secs with peak memory usage of {2}.", fileInfo.Name, stopwatch.Elapsed, Process.GetCurrentProcess().PeakWorkingSet64.ToString("#,#"));
 
                 //Console.WriteLine("Processed: " + fileInfo.Name + " in " + stopwatch.ElapsedMilliseconds + "ms");
-            //}
+            }
 
             Console.ReadLine();
         }

src/ImageProcessor/Imaging/Formats/PngFormat.cs

@@ -14,7 +14,6 @@ namespace ImageProcessor.Imaging.Formats
     using System.Drawing.Imaging;
     using System.IO;
 
-    using ImageProcessor.Common.Extensions;
     using ImageProcessor.Imaging.Quantizers;
     using ImageProcessor.Imaging.Quantizers.WuQuantizer;
 
@@ -103,7 +102,6 @@ namespace ImageProcessor.Imaging.Formats
                 // The Wu Quantizer expects a 32bbp image.
                 if (Image.GetPixelFormatSize(image.PixelFormat) != 32)
                 {
-
                     Bitmap clone = new Bitmap(image.Width, image.Height, PixelFormat.Format32bppPArgb);
                     clone.SetResolution(image.HorizontalResolution, image.VerticalResolution);
 

src/ImageProcessor/Imaging/Quantizers/OctreeQuantizer.cs

@@ -106,7 +106,7 @@ namespace ImageProcessor.Imaging.Quantizers
         /// <returns>The new color palette</returns>
         protected override ColorPalette GetPalette(ColorPalette original)
         {
-            // First off convert the Octree to _maxColors colors
+            // First off convert the Octree to maxColors colors
             ArrayList palette = this.octree.Palletize(this.maxColors - 1);
 
             // Then convert the palette based on those colors

src/ImageProcessor/Imaging/Quantizers/WuQuantizer/PaletteLookup.cs

@@ -89,13 +89,13 @@ namespace ImageProcessor.Imaging.Quantizers.WuQuantizer
                 int deltaAlpha = pixel.Alpha - lookupPixel.Alpha;
                 int distance = deltaAlpha * deltaAlpha;
 
-                var deltaRed = pixel.Red - lookupPixel.Red;
+                int deltaRed = pixel.Red - lookupPixel.Red;
                 distance += deltaRed * deltaRed;
 
-                var deltaGreen = pixel.Green - lookupPixel.Green;
+                int deltaGreen = pixel.Green - lookupPixel.Green;
                 distance += deltaGreen * deltaGreen;
 
-                var deltaBlue = pixel.Blue - lookupPixel.Blue;
+                int deltaBlue = pixel.Blue - lookupPixel.Blue;
                 distance += deltaBlue * deltaBlue;
 
                 if (distance >= bestDistance)

src/ImageProcessor/Imaging/Quantizers/WuQuantizer/WuQuantizer.cs

@@ -12,7 +12,9 @@ namespace ImageProcessor.Imaging.Quantizers.WuQuantizer
     using System.Drawing.Imaging;
 
     /// <summary>
-    /// The wu quantizer.
+    /// Encapsulates methods to calculate the color palette of an image using 
+    /// a Wu color quantizer <see href="http://www.ece.mcmaster.ca/~xwu/cq.c"/>.
+    /// Adapted from <see href="https://github.com/drewnoakes"/>
     /// </summary>
     public class WuQuantizer : WuQuantizerBase, IWuQuantizer
     {
@@ -89,13 +91,14 @@ namespace ImageProcessor.Imaging.Quantizers.WuQuantizer
         {
             byte[] lineIndexes = new byte[image.Image.Width];
             PaletteLookup lookup = new PaletteLookup(lookups);
+
             foreach (Pixel[] pixelLine in image.PixelLines)
             {
                 for (int pixelIndex = 0; pixelIndex < pixelLine.Length; pixelIndex++)
                 {
                     Pixel pixel = pixelLine[pixelIndex];
-                    byte bestMatch = AlphaColor;
-                    if (pixel.Alpha >= alphaThreshold)
+                    byte bestMatch = 0;
+                    if (pixel.Alpha > alphaThreshold)
                     {
                         bestMatch = lookup.GetPaletteIndex(pixel);
                         paletteHistogram[bestMatch].AddPixel(pixel);

src/ImageProcessor/Imaging/Quantizers/WuQuantizer/WuQuantizerBase.cs

@@ -1,4 +1,16 @@
-namespace ImageProcessor.Imaging.Quantizers.WuQuantizer
+// --------------------------------------------------------------------------------------------------------------------
+// <copyright file="WuQuantizerBase.cs" company="James South">
+//   Copyright (c) James South.
+//   Licensed under the Apache License, Version 2.0.
+// </copyright>
+// <summary>
+//   Encapsulates methods to calculate the color palette of an image using
+//   a Wu color quantizer <see href="http://www.ece.mcmaster.ca/~xwu/cq.c" />.
+//   Adapted from <see href="https://github.com/drewnoakes" />
+// </summary>
+// --------------------------------------------------------------------------------------------------------------------
+
+namespace ImageProcessor.Imaging.Quantizers.WuQuantizer
 {
     using System;
     using System.Drawing;
@@ -130,14 +142,14 @@
         /// </param>
         private static void BuildHistogram(Histogram histogram, ImageBuffer imageBuffer, int alphaThreshold, int alphaFader)
         {
-            ColorMoment[,,,] moments = histogram.Moments;
+            ColorMoment[, , ,] moments = histogram.Moments;
 
             foreach (Pixel[] pixelLine in imageBuffer.PixelLines)
             {
                 foreach (Pixel pixel in pixelLine)
                 {
                     byte pixelAlpha = pixel.Alpha;
-                    if (pixelAlpha >= alphaThreshold)
+                    if (pixelAlpha > alphaThreshold)
                     {
                         if (pixelAlpha < 255)
                         {
@@ -156,6 +168,8 @@
                         moments[pixelAlpha, pixelRed, pixelGreen, pixelBlue].Add(pixel);
                     }
                 }
+
+                moments[0, 0, 0, 0].Add(new Pixel(0, 255, 255, 255));
             }
         }
 
@@ -455,19 +469,24 @@
 
             for (int cubeIndex = 0; cubeIndex < cubes.Length; cubeIndex++)
             {
-                var volume = Volume(cubes[cubeIndex], moments);
+                ColorMoment volume = Volume(cubes[cubeIndex], moments);
+
+                if (volume.Weight <= 0)
+                {
+                    continue;
+                }
 
-                if (volume.Weight <= 0) continue;
+                Pixel lookup = new Pixel
+                {
+                    Alpha = (byte)(volume.Alpha / volume.Weight),
+                    Red = (byte)(volume.Red / volume.Weight),
+                    Green = (byte)(volume.Green / volume.Weight),
+                    Blue = (byte)(volume.Blue / volume.Weight)
+                };
 
-                var lookup = new Pixel
-                    {
-                        Alpha = (byte)(volume.Alpha / volume.Weight),
-                        Red = (byte)(volume.Red / volume.Weight),
-                        Green = (byte)(volume.Green / volume.Weight),
-                        Blue = (byte)(volume.Blue / volume.Weight)
-                    };
                 lookups[cubeIndex] = lookup;
             }
+
             return lookups;
         }