/// <summary>
/// Builds a color palette from the given <see cref="PaletteColorHistory"/>.
/// </summary>
/// <param name="palette">
/// The <see cref="ColorPalette"/> to fill.
/// </param>
/// <param name="paletteHistory">
/// The <see cref="PaletteColorHistory"/> containing the sum of all pixel data.
/// </param>
/// <returns>
/// The <see cref="ColorPalette"/>.
/// </returns>
private static ColorPalette BuildPalette(ColorPalette palette, PaletteColorHistory[] paletteHistory)
{
int length = paletteHistory.Length;
for (int i = 0; i < length; i++)
{
palette.Entries[i] = paletteHistory[i].ToNormalizedColor();
}
return palette;
}
/// <summary>
/// Quantizes the image contained within the <see cref="ImageBuffer"/> returning the result.
/// </summary>
/// <param name="imageBuffer">
/// The <see cref="ImageBuffer"/> for storing and manipulating pixel information..
/// </param>
/// <param name="colorCount">
/// The maximum number of colors apply to the image.
/// </param>
/// <param name="lookups">
/// The array of <see cref="Color32"/> containing indexed versions of the images colors.
/// </param>
/// <param name="alphaThreshold">
/// All colors with an alpha value less than this will be considered fully transparent.
/// </param>
/// <returns>
/// The quantized <see cref="Bitmap"/>.
/// </returns>
internal override Bitmap GetQuantizedImage(ImageBuffer imageBuffer, int colorCount, Color32[] lookups, int alphaThreshold)
{
Bitmap result = new Bitmap(imageBuffer.Image.Width, imageBuffer.Image.Height, PixelFormat.Format8bppIndexed);
result.SetResolution(imageBuffer.Image.HorizontalResolution, imageBuffer.Image.VerticalResolution);
ImageBuffer resultBuffer = new ImageBuffer(result);
PaletteColorHistory[] paletteHistogram = new PaletteColorHistory[colorCount + 1];
resultBuffer.UpdatePixelIndexes(IndexedPixels(imageBuffer, lookups, alphaThreshold, paletteHistogram));
result.Palette = BuildPalette(result.Palette, paletteHistogram);
return result;
}
/// <summary>
/// Quantizes the image contained within the <see cref="ImageBuffer"/> returning the result.
/// </summary>
/// <param name="imageBuffer">
/// The <see cref="ImageBuffer"/> for storing and manipulating pixel information..
/// </param>
/// <param name="colorCount">
/// The maximum number of colors apply to the image.
/// </param>
/// <param name="lookups">
/// The array of <see cref="Color32"/> containing indexed versions of the images colors.
/// </param>
/// <param name="alphaThreshold">
/// All colors with an alpha value less than this will be considered fully transparent.
/// </param>
/// <returns>
/// The quantized <see cref="Bitmap"/>.
/// </returns>
internal override Bitmap GetQuantizedImage(ImageBuffer imageBuffer, int colorCount, Color32[] lookups, int alphaThreshold)
{
Bitmap result = new Bitmap(imageBuffer.Image.Width, imageBuffer.Image.Height, PixelFormat.Format8bppIndexed);
result.SetResolution(imageBuffer.Image.HorizontalResolution, imageBuffer.Image.VerticalResolution);
ImageBuffer resultBuffer = new ImageBuffer(result);
PaletteColorHistory[] paletteHistogram = new PaletteColorHistory[colorCount + 1];
resultBuffer.UpdatePixelIndexes(IndexedPixels(imageBuffer, lookups, alphaThreshold, paletteHistogram));
result.Palette = BuildPalette(result.Palette, paletteHistogram);
return(result);
}
/// <summary>
/// Gets an enumerable array of bytes representing each row of the image.
/// </summary>
/// <param name="image">
/// The <see cref="ImageBuffer"/> for storing and manipulating pixel information.
/// </param>
/// <param name="lookups">
/// The array of <see cref="Color32"/> containing indexed versions of the images colors.
/// </param>
/// <param name="alphaThreshold">
/// The alpha threshold.
/// </param>
/// <param name="paletteHistogram">
/// The palette histogram.
/// </param>
/// <returns>
/// The enumerable list of <see cref="byte"/> representing each pixel.
/// </returns>
private static IEnumerable<byte[]> IndexedPixels(ImageBuffer image, Color32[] lookups, int alphaThreshold, PaletteColorHistory[] paletteHistogram)
{
byte[] lineIndexes = new byte[image.Image.Width];
PaletteLookup lookup = new PaletteLookup(lookups);
// Determine the correct fallback color.
byte fallback = lookups.Length < AlphaMax ? AlphaMin : AlphaMax;
foreach (Color32[] pixelLine in image.PixelLines)
{
int length = pixelLine.Length;
for (int i = 0; i < length; i++)
{
Color32 pixel = pixelLine[i];
byte bestMatch = fallback;
if (pixel.A > alphaThreshold)
{
bestMatch = lookup.GetPaletteIndex(pixel);
paletteHistogram[bestMatch].AddPixel(pixel);
}
lineIndexes[i] = bestMatch;
}
yield return lineIndexes;
}
}
