Have you ever been to the mall and seen one of those seemingly random dot patterned posters claiming to be a miraculous and wonderful three-dimensional image? Just "cross your eyes", or "look through it", or do some other seemingly crazy stunt, and the picture swill spring right out at you. Then you sit there and screw your eyes into wall, give yourself a headache and go nuts as three-year-olds walk up, point at the poster and cheer, "Look! A birdie!". Frustrating isn't it?

So what are these images? How do we see them?

What are they?

Basically, a stereogram is a duplicated image that you focus behind in order to see clearly. They are made by taking two identical, or nearly identical images and placing them side by side. This image does not have to be a random image, in fact, the image can be perfectly viewable (like this one below).

Then, when you focus behind the image, the dual image comes together into focus. Since you are looking past the image instead of at the image, your brain interprets the newly focused level as the level the image is at, and your depth perception kicks in, thus causing you to see a three-dimensional image. To learn more about how exactly this imaging works check this out.

How do I see them?

This is the easy part. Essentially, if you are patient, you can learn to see a stereogram. All you need to do is relax, allow your eyes to go out of focus, and look behind the image. Once you see the image, you will really see it, there is no half-way about it. After you have spent some time looking at stereograms, you will get faster and faster at seeing them, until it seems perfectly normal to see the 3D image. Unfortunately, many people have a hard time seeing these the first time, as it is a little unusual for the eyes. If you still canít see these pictures there are a few tricks to help you see them.

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