You have several options.

GD is what you are looking for.

If you want to go Perl, then this link will do exactly (or very close) to what you are looking for:

http://www.dopplegangers.com/perl-cgi/

If you want to go the PHP route

GD is PHP's drawing module. You can create PNG and JPG images with it. Imagine the possibilities: graphs, doodles, interactive games.

http://php.weblogs.com/GD

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