| 摘要 |
VIDEO SIGNAL PROCESSING A method and apparatus for keying TV signals. A keying signal, K, is employed to create first and second modified keying signals, K(A) and K(B), which commence at independent points in time. The modified signals are compared and, as a result, a revised keying signal, R, is produced commencing at the leading edge of one modified keying signal and terminating at the trailing edge of the other. The operator selects R according to one of two rules (i), (ii), the selection being by trial and error: rule (i): if K(A) > X(B) then R = K(A) if K(A) < K(B) then R = K(B) rule (ii) (which is the converse of rule (i)): if K(A) > K(B) then R = K(B) if K(A) < K(B) then R = K(A). In this manner, the revised keying signal R can be made to coincide with the video signal, V, to be keyed. |
