Parallax Error

Want to play a 3D game of an entirely new sort? Try solving this maze.
"Why would that be new?", I hear you say. Simple. The maze can be seen only by people with cross-eyes or at least pretending to have one.

I am talking about those ever-fascinating "Stereograms".

The first time I was intoduced to one of those was when I was in fifth or sixth grade. I was presented with one in a Rotary Club Get-Together meeting (My father is a member). Naturally, I couldn't help thinking why they would want to present me with a board printed with random noise. And I didn't believe them when they said that there was an animal hiding in there, either.
All I could think of was they cheated me by giving me some cheap "Modern Art".

It took me some time to get over the ridiculous idea of seeing an animal "inside" the random noise, when my sister said she saw something (yes, i always believed my sister). When, later I did actually saw the T-Rex inside with perfect 3D effect, with the background moving when I moved my head, I was completely captivated by stereograms. [Mind You, that was a time when even 2d cartoons were new to me. No cable and no video back then]. From then on, I asked my cousins to show them to me whenever they encountered them in any books.

But only recently did I have the time to find out about them. Stereograms work by deception, which should be obvious. It is one of the illusions that use the eye's ability to perceive depth. It uses slightly displaced dots in horizontal and vertical fashion to create a sense of parallax difference, which the eye perceives as depth. What is ingenious is, actually using that to hide a picture in another picture.

Not just random dots, even text can also be a stereogram!
See hundreds of cool hi-quality stereograms here. Think you have mastered the art of stereograms? Try Stereogrammatical movies. And for people that can't seem to get a hang of it, ther are parallax glasses to the rescue!

I can't help but think of applications for this. Maybe we could write programs to use stereograms to hide another picture/data in an image. The secret could be the depth at which the image is stored or one of the objects in the stereogram itself.
Or maybe a....nah....a 3D display? Nice and fast way to a permanent cross-eye disease.