| 摘要 |
PURPOSE:To simplify a device by providing a noise reduction function with use of a conventional frame memory, and utilizing an indispensable chrominance subcarrier phase inverter (chroma-inverter) as a noise reducer instead of applying independently the YC separation between lines. CONSTITUTION:A chroma-inverter for utilizing the YC separation between lines is formed by a 1H memory 315, attenuators 316 and 317, adder 318, BPF319, amplifier 320 and subtracter 321. A signal with three taps is obtained from an output signal of the subtracter 312 in the memory 315, and a chrominance signal is separated in the same manner as the interline YC separation. Both inputs of the subtracter 314 turn out to be signals which have matching phases of chrominance signals and are spaced by one frame. At this time, an output of the subtracter 314 corresponds to a difference signals 314a between frames. On a still picture plane, noise without frame correlation become difference signals, appear at the signal 314a and canceled in the subtracter 312. On the other hand, the interframe difference signal 314a goes to a remarkably high level on an animation, while an output of a coefficient device 313 goes to zero. Accordingly the information in the previous frame is completely eliminated, and will not affect frames afterward. |
