| 摘要 |
A logical comb filter comprises a logic decision section (16, 17) for making logical decisions on the selection of signals and a signal generating section for generating signals to be selected according to the logical decisions. In the signal generating section, a band-pass filter (5) extracts from the input of a composite video signal a signal component centring on a colour sub-carrier frequency, and first and second delay lines (7, 9) generate three line signals based on an inverted output of the band-pass filter (5). A first mean level calculator (11, 13) calculates the mean level between the main signal and a first delay signal obtained as the inverted output of the first delay line (7), and a second mean level calculator (12, 15) calculates the mean level between the first delay signal and a second delay signal obtained as the inverted output of the second delay line (9). One of the output signals and the first delay signal is then selected by a changeover means (14). <IMAGE> |
