Bring your head closer to the screen (10cm will do), your eyes open, and think about what you would to if you have one million dollars. (do not actually try to focus on the image) Keep doing this for about 20 seconds, a stereo image will appear.
This image is from site Paul Nylander. It's generated using the program SISGen http://www.techmind.org/stereo/sisgen.html by William Andrew Steer.
Auto-stereogram are fantastic. Unlike other make-do stereo images, auto-stereogram is alive. I'm wondering if there are systimatic studies made of auto-stereogram. That is, detailing of its limitations, on deapth thickness, viewing angle, animation, and possibilities of color, etc.
Even if it is just confined to gray-scale images of relatively flat surfaces, i kinda feel there's much unexplored utilities.
More details about autostereogram, see Wikipedia: AutostereogramDisqus