Stereograms : A COOL application of Geometry

Stereograms : A COOL application of Geometry

Stereograms (a.k.a. autostereograms, 3D random dot images, SIRDS, SIS, etc.) are incredibly cool. You've probably seen them as posters in the mall or at the beach, or in books by Magic Eye^tm. They are those images that look like TV static, but, if you look at them in a certain way, 3D pictures "pop out" at you.

I wrote a program in Java called StereoGrinder which you can Download. The program and method of generation is explained below. In order to use the program, you'll need to have installed a copy of the Java Development Kit, or at least the Runtime-Environment. StereoGrinder was designed for JDK 1.0, but will compile under 1.1.

For an alternate and comprehensive discussion of Stereograms, see The Stereogram FAQ, maintained by Stuart Inglis.

A Couple Stereogram Examples and How To See Them

To see stereograms, the user must not look at the paper or screen on which the stereogram lies, but look beyond it. That is, you have to "unfocus" your eyes and stare off into space beyond the stereogram. Unfortunately, beginners always seem to have a horrible time doing this (at least I did - couldn't see them for months!) So, there are a few techniques you can use. You can get the idea of what you need to do by holding your pointer finger up about a foot or so from your face and stare through it to the wall. You see two fingers, right? That's what you're supposed to do with stereograms. It's a lot of fun to do this with people, staring beyond their heads, and seeing that they really do have four eyes (an affect of this double-vision staring).

One thing that is VERY IMPORTANT is that, when you try to "see" the stereogram, you keep your head level and eyes horizontal with the screen. If you tilt your head just a little bit, it won't work. Also, on this first one, I have put in two boxes to help you align yourself. When you get double vision, you may see two sets of box-pairs. If so, you need to adjust your focus to join the middle two together so that, in the end you see a solid square and two flickering ones. When you see that, your focus is about right to see the rest of the picture, and you can look up a bit. If you're still having problems, for more techniques on how to see stereograms look at the Stereogram FAQ (not part of this site)

Sample Stereogram A - Random Dot

See the image from which this stereogram came
(cheater's way to find out "what it is")

Sample Stereogram B - Image Based

See the image from which this stereogram came

How are these illusions made??? and How can I use this awesome program that David made to create Stereograms? How does Geometry fit in?

It's on to the technical stuff!!

-David