Okay, this is just a cool optical illusion. Follow the directions carefully for it to work. Stare at the yellow fish. Don't blink or take your eyes off it. After about 10 seconds, press space, keeping your eyes on the fish. Ta-da!!! There's no color in the second picture. It's all in your brain. The effect lasts longer if you keep your eyes on the fish after pressing space.
Credit to the Brain Games show, from which I got the idea. In case you can't tell, it's a lazily drawn picture of a river, a tree, and a fence. You know, one of those lazy pictures that still take you at least an hour to complete.
