C#转换为灰度图的算法
public static unsafe void GrayscaleImage(BitmapData sourceImage, IntPtr destBuffer)
{
int width = sourceImage.Width;
int height = sourceImage.Height;
// do the job
var src = (byte*) sourceImage.Scan0.ToPointer();
var dst = (byte*) destBuffer.ToPointer();
int srcOffset = sourceImage.Stride - width*3;
// for each line
for (int y = 0; y < height; y++)
{
// for each pixel
for (int x = 0; x < width; x++, src += 3, dst++)
{
// use integer arithmetic to instead of doubles to speed up calculation
*dst = (byte) ((2125*src[2] + 7154*src[1] + 721*src[0])/10000);
}
src += srcOffset;
}
}