| 摘要 |
PURPOSE:To attain automatically optimum picture quality adjustment to various video signals different in horizontal scanning frequency by detecting a horizontal scanning frequency of a video signal and using the detecting signal to control the frequency characteristic of the video signal. CONSTITUTION:A video signal (a) is inputted to an input terminal 1 and a signal (b) delayed by tau is obtained at a delay circuit 4 having a delay time tau of a picture quality adjusting circuit 14. Further, a signal (c) delayed by 2tau to the input video signal (a) is obtained by a delay circuit 5. The signal (c) and the video signal (a) are added by an adder circuit 6 so as to halve the gain and a signal (d) is outputted. It is subtracted from the signal (b) at a subtraction circuit 7 and a profile signal (e) is outputted and added to the signal (b) at an adder circui 9 via a gain control circuit 8 and a video signal (f) subject to picture quality adjustment is outputted from an output terminal 3. Further, a horizontal synchronizing signal from an input terminal 10 is detected for frequency at a frequency detection circuit 11. This detection signal is fed to a control circuit 12 to control the delay time of the delay circuits 4, 5. Thus, the frequency band emhasized for the video signal in response to the horizontal scanning frequency is controlled.
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