| 摘要 |
PURPOSE:To remove dot-like interference which occurs in the trimming of a video by constituting a titled device in such a way that a noise reduction circuit detects the non-correlation signal of chrominance components and only a non-correlation part in a notch filter circuit is operated. CONSTITUTION:The output waveform of a correlation circuit 36 consists of a signal equivalent to the non-correlation part of the chrominance components and multiple feedback error signals (noise). A detection circuit 41 full-wave- rectifies the signals and generates a level difference between the non correlation signals and the multiple feedback error signal part. A constant threshold level is set in a comparator 42, and it is possible to distinguish the non-correlation signals with level difference and the multiple feedback error signals. Namely, the comparator 42 generates a pulse which comes to 'H' only in the part equivalent to the non-correlation signal, for example. With the pulse, a switch 111 switching the operation of a notch filter circuit 110 is turned ON. Consequently, the notch filter 110 operates only in a non-correlation signal period to remove dot interference.
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