private static TextureByteIndexPalette ReduceColorPalette(string name, Bitmap bitmap, List <Color> allColors, ColorPaletteAlgorithm algorithm, int targetColors)
{
if (targetColors > 256)
{
throw new ArgumentOutOfRangeException(nameof(targetColors));// Indices over byte.MaxValue are not supported
}
byte[] indices = new byte[bitmap.Width * bitmap.Height];
switch (algorithm)
{
case ColorPaletteAlgorithm.MostUsedColorsRGB:
{
int[] colorUsage = new int[allColors.Count];
// Calculate usage
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
colorUsage[allColors.IndexOf(bitmap.GetPixel(x, y))]++;
}
}
var byUsage = allColors.OrderByDescending((col) =>
{
int index = allColors.IndexOf(col);
return(colorUsage[index]); // How many times was the color used
}).ToArray();
Array.Resize(ref byUsage, targetColors);
// Get nearest pixel by RGB
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
indices[x + y * bitmap.Width] = (byte)NearestColorRGB(byUsage, bitmap.GetPixel(x, y));
}
}
return(new TextureByteIndexPalette(name, bitmap.Width, bitmap.Height, indices, byUsage));
}
case ColorPaletteAlgorithm.MostUsedColorsHSB:
{
int[] colorUsage = new int[allColors.Count];
// Calculate usage
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
colorUsage[allColors.IndexOf(bitmap.GetPixel(x, y))]++;
}
}
var byUsage = allColors.OrderByDescending((col) =>
{
int index = allColors.IndexOf(col);
return(colorUsage[index]); // How many times was the color used
}).ToArray();
Array.Resize(ref byUsage, targetColors);
// Get nearest pixel by HSB
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
indices[x + y * bitmap.Width] = (byte)NearestColorHSB(byUsage, bitmap.GetPixel(x, y));
}
}
return(new TextureByteIndexPalette(name, bitmap.Width, bitmap.Height, indices, byUsage));
}
case ColorPaletteAlgorithm.BasicPaletteNearestRGB:
{
if (targetColors != 256)
{
throw new ArgumentOutOfRangeException(nameof(targetColors));
}
var palette = BasicPalette;
// Get nearest pixel by RGB
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
indices[x + y * bitmap.Width] = (byte)NearestColorRGB(palette, bitmap.GetPixel(x, y));
}
}
return(new TextureByteIndexPalette(name, bitmap.Width, bitmap.Height, indices, palette));
}
case ColorPaletteAlgorithm.BasicPaletteNearestHSB:
{
if (targetColors != 256)
{
throw new ArgumentOutOfRangeException(nameof(targetColors));
}
var palette = BasicPalette;
// Get nearest pixel by HSB
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
indices[x + y * bitmap.Width] = (byte)NearestColorHSB(palette, bitmap.GetPixel(x, y));
}
}
return(new TextureByteIndexPalette(name, bitmap.Width, bitmap.Height, indices, palette));
}
}
throw new NotSupportedException();
}
public static TextureByteIndexPalette CreateFromBitmap(string name, Bitmap bitmap, ColorPaletteAlgorithm algorithm = ColorPaletteAlgorithm.BasicPaletteNearestHSB)
{
var indices = new byte[bitmap.Width * bitmap.Height];
var colors = new List <Color>();
// Add all colors into the palette (to count them)
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
var c = bitmap.GetPixel(x, y);
if (!colors.Contains(c))
{
colors.Add(c);
}
}
}
if (colors.Count <= 256)
{
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
Color c = bitmap.GetPixel(x, y);
int index = colors.IndexOf(c);
indices[x + y * bitmap.Width] = (byte)index;
}
}
return(new TextureByteIndexPalette(name, bitmap.Width, bitmap.Height, indices, colors.ToArray()));
}
else
{
return(ReduceColorPalette(name, bitmap, colors, algorithm, 256));
}
}