First, I agree fully with the part about handicap access, and I think that it should be a show stopper for any moral programmer; even one getting paid for doing such work.
Second, stringing together images is a bad idea, because you can look at the image names and (presumably) the bot can just translate the image tags to the words. Simple obfuscation might not work. My own preference for a module to do all graphics stuff is Gimp/Perl. The Perl-Server that comes with this moves the graphics processing into a seperate process from the webserver, so you only have the glue in all the apache (or ...) processes. Note however that the locking doesn't work in all versions, so I just flock() a lockfile.