private static IEnumerable<byte[]> indexedPixels(ImageBuffer image, Pixel[] lookups, int alphaThreshold, int maxColors, PaletteColorHistory[] paletteHistogram)
{
int pixelsCount = image.Image.Width * image.Image.Height;
var lineIndexes = new byte[(int)System.Math.Ceiling(image.Image.Width / System.Math.Log(256.0, maxColors))];
PaletteLookup lookup = new PaletteLookup(lookups);
--maxColors;
foreach (var pixelLine in image.PixelLines)
{
for (int pixelIndex = 0; pixelIndex < pixelLine.Length; pixelIndex++)
{
Pixel pixel = pixelLine[pixelIndex];
byte bestMatch = (byte)maxColors;
if (pixel.Alpha > alphaThreshold)
{
bestMatch = lookup.GetPaletteIndex(pixel);
paletteHistogram[bestMatch].AddPixel(pixel);
}
switch (maxColors)
{
case 256 - 1:
lineIndexes[pixelIndex] = bestMatch;
break;
case 16 - 1:
if (pixelIndex % 2 == 0) { lineIndexes[pixelIndex / 2] = (byte)(bestMatch << 4); }
else { lineIndexes[pixelIndex / 2] |= (byte)(bestMatch & 0x0F); }
break;
case 2 - 1:
if (pixelIndex % 8 == 0) { lineIndexes[pixelIndex / 8] = (byte)(bestMatch << 7); }
else { lineIndexes[pixelIndex / 8] |= (byte)((bestMatch & 0x01) << (7 - (pixelIndex % 8))); }
break;
}
}
yield return lineIndexes;
}
}
private static ColorPalette BuildPalette(ColorPalette palette, PaletteColorHistory[] paletteHistogram)
{
for (int paletteColorIndex = 0; paletteColorIndex < paletteHistogram.Length; paletteColorIndex++)
{
palette.Entries[paletteColorIndex] = paletteHistogram[paletteColorIndex].ToNormalizedColor();
}
return palette;
}
internal override Image GetQuantizedImage(ImageBuffer image, int colorCount, Pixel[] lookups, int alphaThreshold)
{
var result = new Bitmap(image.Image.Width, image.Image.Height, PixelFormat.Format8bppIndexed);
var resultBuffer = new ImageBuffer(result);
var paletteHistogram = new PaletteColorHistory[colorCount + 1];
resultBuffer.UpdatePixelIndexes(IndexedPixels(image, lookups, alphaThreshold, paletteHistogram));
result.Palette = BuildPalette(result.Palette, paletteHistogram);
return(result);
}
internal override Image GetQuantizedImage(ImageBuffer image, int colorCount, int maxColors, Pixel[] lookups, int alphaThreshold)
{
PixelFormat pf;
switch (maxColors)
{
case 256: pf = PixelFormat.Format8bppIndexed; break;
case 16: pf = PixelFormat.Format4bppIndexed; break;
case 2: pf = PixelFormat.Format1bppIndexed; break;
default: throw new QuantizationException(string.Format("The target amount of colors is not supported. Requested {0} colors.", maxColors));
}
var result = new Bitmap(image.Image.Width, image.Image.Height, pf);
var resultBuffer = new ImageBuffer(result);
var paletteHistogram = new PaletteColorHistory[colorCount + 1];
resultBuffer.UpdatePixelIndexes(indexedPixels(image, lookups, alphaThreshold, maxColors, paletteHistogram));
result.Palette = BuildPalette(result.Palette, paletteHistogram);
return result;
}
internal override Image GetQuantizedImage(ImageBuffer image, int colorCount, int maxColors, Pixel[] lookups, int alphaThreshold)
{
PixelFormat pf;
switch (maxColors)
{
case 256: pf = PixelFormat.Format8bppIndexed; break;
case 16: pf = PixelFormat.Format4bppIndexed; break;
case 2: pf = PixelFormat.Format1bppIndexed; break;
default: throw new QuantizationException(string.Format("The target amount of colors is not supported. Requested {0} colors.", maxColors));
}
var result = new Bitmap(image.Image.Width, image.Image.Height, pf);
var resultBuffer = new ImageBuffer(result);
var paletteHistogram = new PaletteColorHistory[colorCount + 1];
resultBuffer.UpdatePixelIndexes(indexedPixels(image, lookups, alphaThreshold, maxColors, paletteHistogram));
result.Palette = BuildPalette(result.Palette, paletteHistogram);
return(result);
}