Stereogram

Part of speech: noun

Definitions

1. A type of image that appears flat but reveals a hidden 3D shape through specific viewing techniques enables depth perception when both eyes focus correctly
2. An image that creates an illusion of depth by requiring viewers to adopt a particular gaze allows the brain to perceive hidden three-dimensional features
3. A visual representation that seemingly exists in two dimensions while concealing a three-dimensional form that is revealed through proper focus from both eyes offers a unique depth experience

Etymology: "Stereogram" is built from two Greek elements: "stereos," meaning solid or firm, and "gramma," meaning something written or drawn. The second part is the same root that gives English "program" and "telegram." Put together, the word describes a picture that records depth, a flat surface that holds a solid shape within it. The "stereo-" half of the word was already attached to ideas of three-dimensionality long before the picture form arrived. Stereograms rely on the fact that each eye sees a slightly different view, so a pattern printed on a flat page can be fused by the brain into a form that seems to project or recede. Note that the word is a modern coinage from classical roots, not something ancient Greeks would have recognised. Its earliest English use is documented in the source only as a compound of those two Greek elements.

Synonyms: 3D image, stereoscopic image