A stereogram is an optical illusion that creates the perception of a three-dimensional image when viewed correctly. Stereograms are typically created by combining two slightly different images, which are then viewed through a stereoscope or by using the free-viewing technique. When viewed correctly, the two images merge to create a single three-dimensional image.
Stereograms have been used for centuries to create a variety of optical illusions and effects. They have also been used in scientific research to study the human visual system. In recent years, stereograms have become increasingly popular as a form of entertainment, and there are now many websites and books that provide free stereograms for viewing.
