Magic Eye Stereogram

At first, a field of random noise. But if you look throughthe screen (divergent focus), a 3D Circle will pop out of the background, appearing to float in mid-air.

1. Put your face close to the screen.
2. Relax your eyes and stare "through" the image as if looking at something far away.
3. Slowly pull back from the screen. Do not focus on the surface.
4. Wait for the hidden shape to "click" into place.

This is a Random Dot Autostereogram. It contains two identical versions of the noise offset by a small distance. By "triangulating" your eyes incorrectly (divergence), you force each eye to see a different set of noise. The brain combines these disparate signals into a single 3D image using Stereopsis.