Quantizer works. Encoding is the issue.

Former-commit-id: 6f7bfcd5302cf0ea9991dec53a4521906eaea4ea
Former-commit-id: 6144a66e2c92b9adb9a33f9f04572837fcd8226c
Former-commit-id: 853c19e80f3b000f62d913916dd9c35c0e3a3627

src/ImageProcessor/Formats/Bmp/BmpEncoder.cs

@@ -108,6 +108,7 @@ namespace ImageProcessor.Formats
         /// </param>
         private static void WriteImage(BinaryWriter writer, ImageBase image)
         {
+            // TODO: Check this as Bitmaps can have an alpha channel.
             int amount = (image.Width * 3) % 4;
             if (amount != 0)
             {

src/ImageProcessor/Formats/Gif/Quantizer/OctreeQuantizer.cs

@@ -114,7 +114,7 @@ namespace ImageProcessor.Formats
         protected override List<Bgra> GetPalette()
         {
             // First off convert the Octree to maxColors colors
-            List<Bgra> palette = this.octree.Palletize(this.maxColors - 1);
+            List<Bgra> palette = this.octree.Palletize(Math.Max(this.maxColors - 1, 1));
 
             // Add empty color for transparency
             palette.Add(Bgra.Empty);

src/ImageProcessor/Formats/Gif/Quantizer/QuantizedImage.cs

@@ -60,11 +60,12 @@ namespace ImageProcessor.Formats
         /// <returns></returns>
         public Image ToImage()
         {
+            // TODO: Something is going wrong here. We have a palette.
             Image image = new Image();
             int pixelCount = Pixels.Length;
             byte[] bgraPixels = new byte[pixelCount * 4];
 
-            for (int i = 0; i < pixelCount; i++)
+            for (int i = 0; i < pixelCount; i += 4)
             {
                 Bgra color = Palette[Pixels[i]];
                 bgraPixels[i + 0] = color.B;

src/ImageProcessor/Formats/Gif/Quantizer/Quantizer.cs

@@ -11,7 +11,6 @@
 namespace ImageProcessor.Formats
 {
     using System.Collections.Generic;
-    using System.Linq;
 
     /// <summary>
     /// Encapsulates methods to calculate the color palette of an image.
@@ -55,16 +54,16 @@ namespace ImageProcessor.Formats
             // Call the FirstPass function if not a single pass algorithm.
             // For something like an Octree quantizer, this will run through
             // all image pixels, build a data structure, and create a palette.
-            if (!singlePass)
+            if (!this.singlePass)
             {
-                FirstPass(imageBase, width, height);
+                this.FirstPass(imageBase, width, height);
             }
 
             byte[] quantizedPixels = new byte[width * height];
 
-            SecondPass(imageBase, quantizedPixels, width, height);
+            this.SecondPass(imageBase, quantizedPixels, width, height);
 
-            return new QuantizedImage(width, height, GetPalette().ToArray(), quantizedPixels);
+            return new QuantizedImage(width, height, this.GetPalette().ToArray(), quantizedPixels);
         }
 
         /// <summary>
@@ -100,7 +99,7 @@ namespace ImageProcessor.Formats
 
             // Convert the first pixel, so that I have values going into the loop
             Bgra previousPixel = source[0, 0];
-            byte pixelValue = QuantizePixel(previousPixel);
+            byte pixelValue = this.QuantizePixel(previousPixel);
 
             output[0] = pixelValue;
 
@@ -115,7 +114,7 @@ namespace ImageProcessor.Formats
                     if (sourcePixel != previousPixel)
                     {
                         // Quantize the pixel
-                        pixelValue = QuantizePixel(sourcePixel);
+                        pixelValue = this.QuantizePixel(sourcePixel);
 
                         // And setup the previous pointer
                         previousPixel = sourcePixel;

tests/ImageProcessor.Tests/Formats/EncoderDecoderTests.cs

@@ -59,7 +59,9 @@
         }
 
         [Theory]
+        [InlineData("../../TestImages/Formats/Jpg/Backdrop.jpg")]
         [InlineData("../../TestImages/Formats/Bmp/Car.bmp")]
+        [InlineData("../../TestImages/Formats/Png/cmyk.png")]
         public void QuantizedImageShouldPreserveMaximumColorPrecision(string filename)
         {
             if (!Directory.Exists("Quantized"))