Anaglyph

An anaglyph is a stereoscopic image technique in which two slightly different images of the same subject—representing the left- and right-eye perspectives—are superimposed in different colours, typically red and cyan (historically often red and green). When viewed through correspondingly coloured filters, each eye sees only its intended image, allowing the brain to perceive depth.

The principle was first described by Wilhelm Rollmann in 1853. In 1858, Joseph D'Almeida described a method for projecting three-dimensional magic lantern slide shows using red and green filters for an audience wearing corresponding coloured glasses. D'Almeida is credited with the first practical realisation of three-dimensional images using the anaglyph principle.

The first practical photographic anaglyph process was later developed by Louis Ducos du Hauron, who described the method and produced the first printed anaglyphs in 1891. He also introduced the term anaglyph.