Funny you asked. I wonder what I did with the colormap reducer I did when I thought it might be interesting to crop USGS maps to display as background for gpsapp... before proving to myself that 128x32 was simply too small for it to be worthwhile.

So, yeah, that's the thing. How do you allocate a colormap that makes sense? I don't know that I'm clever enough to figure out how to dither without doing something that will be a pig.