| 摘要 |
PURPOSE:To attain television special effect with a simple circuit by superimposing a key signal to the 1st video signal, and extracting a key signal from the 2nd video signal for video image reproduction obtained based on the 1st video signal. CONSTITUTION:A video signal 10 is brought into 0 level by a superimposing circuit 1 when no key signal 15 exists, brought into a level below a pedestal level when the key signal 15 exists, and when the video signal has a level over the pedestal level, the signal is transmitted to a processing section 4 while keeping the said level. Picture processing such as shrinking, magnification, rotation or skew is applied to the processing section 4, a reproducing video signal 20 is transmitted, its signal and a reference value of a reference value generator 3 outputting a reference value smaller than a black clip value are compared by a comparator 2 and the key signal 15 is generated.
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