什么是一个好的，优化的C/ c++算法，用于将一个24位位的位图转换为16位的抖动?

I've been looking for an optimized (i.e., quick) algorithm that converts a 24-bit RGB bitmap to a 16-bit (RGB565) bitmap using dithering. I'm looking for something in C/C++ where I can actually control how the dithering is applied. GDI+ seems to provide some methods, but I can't tell if they dither or not. And, if they do dither, what mechanism are they using (Floyd-Steinberg?)I've been looking for an optimized (i.e., quick