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Ok, I think we've all seen stereograms... Well, whether or not we can "see" them, we're familiar with them. Well this one is a bit different...

Check out this teapot blowing a black and white translucent bubble!!!


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Ahh, that is weird...and any clue what in the world calte is?... or did I even read that right?? 8-Þ

It says "Caltech" in the original version, but the bubble covers the "ch" in this one. You can only read through it if you know what you're looking for. So maybe you can't really read through it. :)

Aw, that makes sense... It took me forever to be able to see those things. 8-Þ And it seems different on the computer than in a book. ...Do you have any good links for sites of them?? 8-}

Not really. I just stumbled upon this one because it was a recent Astronomy Picture of the Day. (April 30, 2002)

I can't see it! I can never see these! What does this say about my eyes, which are 20/20?

Usually people who can't see these things can't process data from both eyes equally. If one of your eyes is very dominant, you'll only see half of the image. You need to see the other half at the same time in order for it to produce the depth signals.

I think it also helps to understand the physics behind the illusion. Some people say "just lose focus on it and the image will appear" but that's pretty vague and misleading. I think of it as "my right eye needs to see this dot at the same time as my left eye sees this copy of that dot to its immediate left, so I'll look between them and make my eyes converge BEHIND the print (this is different than focus) until the two dots come together." At that point the 3D image is in focus, but it's often not immediately seen. So I just continue staring at that single dot and let my eyes and brain process the depth information from my peripheral vision. Eventually the depth map gets drawn a little more so I can move around and explore it, but if I come to an edge where my eyes aren't sure what's around it, I sit there and wait again. Eventually I get my eyes to remember the whole image so I can move freely around. Some stereograms come faster than others - the process I just described is for the harder ones.

Here are pages one/two and three/four of the author's "Simplified pictoral explanation of the algorithm" behind stereograms. Understanding how they're made might help you understand how to see them. Mainly, it has a good diagram showing how the two eye paths converge behind the print.

Well that really does explain my problem then, because my eyes do not move together. I actually wear reading glasses even though I have perfect vision because my eyes get fatigued. When I was a child I went to an eye clinic to do eye exercises to help tran my eyes to work together. Sigh. I guess I will never be able to see these cool optical illusions.

Isn't this the type of case where they would put a patch over the stronger eye to force the weaker one to develop? Or maybe that's only effective during the early developmental years.

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