private static void UpdateNumBitsPerChannel(Rgba32 pixel, NumBitsPerChannel bpc)
{
bpc.R = Math.Max(bpc.R, GetMinimumColorDepth(pixel.R));
bpc.G = Math.Max(bpc.G, GetMinimumColorDepth(pixel.G));
bpc.B = Math.Max(bpc.B, GetMinimumColorDepth(pixel.B));
bpc.A = Math.Max(bpc.A, GetMinimumColorDepth(pixel.A));
}
public static int GetMinimumColorDepthForDisplay(Image <Rgba32> image)
{
if (IsAnyPartialTransparency(image))
{
return(32);
}
if (!IsAnyPixel(image, (x, y, pixel) => !IsBlack(pixel) && !IsWhite(pixel)))
{
return(1);
}
var bpc = new NumBitsPerChannel();
ForeachPixel(image, (x, y, pixel) => UpdateNumBitsPerChannel(pixel, bpc));
if (bpc.RgbLessThan(2))
{
return(3 * 1);
}
if (bpc.RgbLessThan(3))
{
return(3 * 2);
}
if (bpc.RgbLessThan(5))
{
return(3 * 3);
}
return(3 * 4);
}
public static BitmapEncoding GetIdealBitmapEncoding(Image <Rgba32> image, bool hasIcoMask)
{
if (IsAnyPartialTransparency(image))
{
return(BitmapEncoding.Pixel_argb32);
}
var numColors = GetNumberOfDistinctColors(image, !hasIcoMask);
if (numColors <= 2)
{
return(BitmapEncoding.Pixel_indexed1);
}
if (numColors <= 4)
{
return(BitmapEncoding.Pixel_indexed2);
}
if (numColors <= 16)
{
return(BitmapEncoding.Pixel_indexed4);
}
if (numColors <= 256)
{
return(BitmapEncoding.Pixel_indexed8);
}
var bpc = new NumBitsPerChannel();
ForeachPixel(image, (x, y, pixel) => UpdateNumBitsPerChannel(pixel, bpc));
if (hasIcoMask || !IsAnyAlphaChannel(image))
{
if (bpc.RgbLessThan(6))
{
return(BitmapEncoding.Pixel_rgb15);
}
return(BitmapEncoding.Pixel_rgb24);
}
return(BitmapEncoding.Pixel_argb32);
}
