PNG is a lot more complicated than GIFs, but then again, it does a lot more. If it is truly rectangular, and these are being output to the web, you can make some very small and very quick-loading GIF images by having perl output an IMG tag to a small GIF, and changing the HEIGHT and WIDTH tags. If not on the web, the GD option mentioned above (thanks btrott!) may be your best bet. But the HEIGHT and WIDTH trick (along with some other HTML tweaking) can produce really nice looking results.