I don't know. I think optipng is basically optimal for what it does. If you use the -o7 flag, I believe it uses every available combination of settings that a png file can have, as well as using the minimal color space.
However, what would be really cool is something which would dither down, based on some of the research that is going on in that field. I saw a java applet once that could dither almost anything to 256 colors with barely any noticeable degradation. For something like the iphone, or any other memory limited/bandwidth limited device this would be awesome.
However, what would be really cool is something which would dither down, based on some of the research that is going on in that field. I saw a java applet once that could dither almost anything to 256 colors with barely any noticeable degradation. For something like the iphone, or any other memory limited/bandwidth limited device this would be awesome.