Television animation store: Digital chroma, key and mixer units

The digital chroma-key (also called color separation overlay) unit described is incorporated in a digital video storage system which is used in the preparation of animated picture sequences obtained from an electronic rostrum camera. The circuitry operates on digital YUV video signals and can generate key signals from any selected color in the foreground picture; these key signals are then used to replace the areas of the chosen color in the foreground picture by a background picture using linear, additive key techniques. In addition, key signals can be obtained from the foreground's luminance component. The technical details and ergonomic control of the unit are described. Problems associated with digital processing are discussed.