Processing circuit for video signals.

摘要

A first shaped video signal V1K1 and a second shaped video signal V2K2, are combined so as to generate a third shaped video signal V3' given by V3' = V1 K1 [1 - K2(1 - P12)] + V2K2(1 - K1P12> where P12 is a priority signal. A key signal K3 given by K3 = 1 - (1 - K1)(1 - K2> is also generated. An output processor receives the shaped video signal V3', the key signal K3 and a matte signal M3. In a first mode of operation, the output video signal V3'' of the output processor is given by V3'' = V3 + M3(1 - K3> and the key signal K3' that is generated by the output processor has a constant value, and in a second mode of operation of the output processor the output video signal is given by V3'' = V3'/K3 and the key signal K3' is directly proportional to K3. <IMAGE>