Re: Resize and minimize
Posted: 2009-05-22T09:54:01-07:00
use -depth 8 and/or -colors 256 (or less)
GIF file format is 8 bit depth only by it defintion.
To make GIF smaller you need to reduce the colors, or order the colors so that its compression algorthim can find more 'common color sequences'. Normal IM color dithering does not do this very well, as it uses a fairly psuedo-random dither method.
You may get better results using some method of -order-dithering
See the lat part of Video to GIF, Optimization Summary
http://www.imagemagick.org/Usage/video/#gif
where ordered dither is interoduced. It does help a lot for very large single frame GIFs, and not just smaller multi-frame GIFs.
I would love to try and implement some form of ordered dither using a user supplied, or automatic color quantized, color map, but have yet to find a good reference to the techniques involved.