Patent ID: 6950149

Claim:
A comb filter comprising: a bandpass filter for receiving a composite color video signal, extracting a frequency band component of a chrominance signal from said composite color video signal, and outputting the extracted frequency band component; a first delay circuit for receiving the output of said bandpass filter and delaying said output by one horizontal period; a first subtracting circuit for obtaining a subtracted output between the output signal of said bandpass filter and an output signal of said first delay circuit; an adding circuit for obtaining an added output of the output signal of said bandpass filter and the output of said first delay circuit; a switching circuit for switching between the output of said bandpass filter and the output of said subtracting circuit and outputting the switched output; a correlation detecting circuit for receiving the output of said first subtracting circuit and the output of said adding circuit and, based on a relationship between the two outputs, outputting a binary signal that indicates correlation between the output signal of said bandpass filter and the output signal of said first delay circuit; a second delay circuit for delaying said binary signal coming from said correlation detecting circuit by one horizontal period; and an arithmetic circuit for receiving said binary signal from said correlation detecting circuit and the signal from said second delay circuit and, from an operational results of said binary signal and said signal from said second delay circuit, outputting a select signal for performing switching control on said switching circuit; wherein a chrominance signal is obtained from said switching circuit.