| 摘要 |
PURPOSE:To reduce color noises without exerting evil influence upon the color of the contour part of a picture by varying the band width of a BPF means for extracting a color signal from a narrow to a wide band when a luminance signal varies in level. CONSTITUTION:A composite color video signal is supplied to a BPF 3 through a BPF 1 and a delay circuit 2 to extract a color signal, and outputs from the BPFs 1 and 3 are supplied to a switch 4 respectively. The center frequencies of the signal passing bands of those BPFs 1 and 3 are equal to each other, and the BPF 1 has a narrower band than the BPF 3. From the luminance signal separated from the composite color video signal, its level variation part is detected by an HPF 5. The output signal of the HPF 5 is rectified by a rectifying circuit 6 on full-wave basis to obtain a detection signal having pulses of positive components. Those pulses are supplied to the switch 4, which is then driven to supply the output signal of the BPF 3 to a color demodulating circuit as a substitute for the output signal of the BPF 1. |
