toys

Random-Dot Stereograms

Random-dot stereograms are those flat usually-meaningless images that, when you cross your eyes just right, pop out of the page or the screen and create a 3D somethingorother. They were All The Rage for some time, and the world is still full of books / posters / calendars / stained-glass windows with the things on them. A few years ago, I sat down and figured out the algorithm, and now I've packaged it as a simple Perl module, RaDoSt.

You can't actually play with module here at the moment, because I haven't installed GD on the server (and because I don't want you bogging down the server running it). But you can see the module docs, the code itself, and the two output gifs (smaller and in color and larger and black-and-white) produced by the sample code in the docs.

Feel free to redistribute and reuse and modify and so on. Feedback to oh I dunno how about here.

Note on terminology: a stereogram is any flat thing intended to be viewed in such a way as to make it pop up and appear 3D. The special kind consisting of a single image that you (un)cross your eyes at to do the popping-up is, technically, an autostereogram. And the ones made with random dots are (surprise!) random-dot autostereograms. I tend to forget the "auto" part. And in general the very arty things in the "Magic Eye" books aren't random-dot at all, but based on repeating coherent patterns, flowers, vases, Richard Nixon, etc. But we're easy...

This page last updated
October 15, 1999

toys