Seeing Hidden Images in 3D
Hidden images in stereograms rely on your eyes ability to do something called parallel viewing. This is how we see in 3D. For it to “work,” you must first aim your eye through the image into the distance. Those old “Magic Eye” posters instructed viewers to relax their eyes, get close, and just stare into the picture.
Though your eyes still see everything in your line of sight, your focal point shifts without you realizing it. Instead of focusing on single details in the image, your eyes begin to pull out details on their own. As you stare, you begin to feel like you are going a little cross-eyed. Certain parts of the hidden image are revealed as you continue to stare into the picture. Once you’ve detected the image, you can often train your eyes to look around and see everything that’s hidden.
How Can I Try It at Home?
Want to get an idea of how stereo images work? You can do so even without a “Magic Eye” poster around. Here’s what you need to do.
First: Pick an object in the distance. It works best if you can look out a window to some very specific point in the distance. I tried it staring through my window at the chimney of another home.
Second: Keep staring.
Third: While you are staring, bring both of your fingers up in front of your face in front of your eyes. Point them directly at each other right in your line of vision. Make sure the tips of your fingers touch.
Fourth: Keep staring! Now, you may notice that something odd has appeared between the tips of your fingers. Does it look like a mini hot dog? (They call this the “mini-frankfurter” experiment, and now you know why!)
Fifth: Keep staring into the distance. Don’t let the little hot dog divert your attention. Keep focused and then try this trick. Pull your fingers slightly apart and watch in amazement as the mini hot dog floats in the air!
Voila! This is how those Magic Eye pictures work too. While your eyes are busy focusing through the picture, your brain plays a trick on you by adding something extra to what you see.