wanted grayscale dithering routine i have some color gifs which i would like to archive in a much smaller size using a grayscale palette of shades the quantization to grays introduces some ugly bands in the pictures which can be nicely eliminated by dithering up to now i have used xv to process the images but now i would like to automate the procedure the problem is that xv can t i think convert images automatically and the obvious alternative pnmplus ppmquant and pnmdither don t even get close to xv s quality pnmdither apparently dithers in rgb even though the images are in grayscale the dithering routine in xv seems to use the natural image colors for the dither is this or any similar routine available in the public domain if so where niclas mattsson exjob math chalmers se
