Can anyone point me in the direction of a module that allows me to display an actual picture?

Have you looked at GD and friends? It's sometimes a PITA to build but I've used it in the past to create images "on the fly" and display them for various reasons. IIRC you can do some neat stuff with Image::Magick as well although I've no experience myself with that module.

With GD the trick is to emit a line "Content-type: image/{image type}" and putting stdout into binary mode before emitting the image.