A film or television graphical effect for compositing two full frame images together, by discriminating the visual information into values of color and light. A particular colour is isolated by the system, used as a template or matte and then replaced with an alternate image or video.
Most often used by weather presenters, virtual studios and special effects technicians.
See also: Chroma key, luma key, matte key, bluescreen, composite video, chrominance signal, Federal Standard 1037C