chromakey

a means of separating a foreground image from its background by use of chroma. Most often used chromakey colours are blue or green
Found on http://www.animationpost.co.uk/doping/glossary.htm

chromakey

overlay in which masking is controlled by a signal representing the parts of an image which have a specific colour, for example, a uniformly coloured background
Found on http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=723-04-22
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