Stereogram

A stereogram is an optical image designed to create the illusion of three-dimensional depth from a two-dimensional picture. It works by presenting two nearly identical images with slight differences, which the brain combines to perceive a hidden 3D shape or scene. When viewed with proper focus—either by crossing your eyes or using special glasses—the subtle differences in the patterns cause your brain to interpret depth, revealing the concealed image. Stereograms are often used for visual entertainment, artistic purposes, and depth perception training.