| 摘要 |
PURPOSE:To improve a line crawl and the SN ratio of a video signal without causing deterioration in phase characteristics by providing a means which extracts the contour signal of a video signal and inverts and controls its polarity, and mixes the output of it with the video signal. CONSTITUTION:The contour signal S4 is generated through a 1H (one horizontal scanning period) delay circuit 1 and a contour signal generating circuit 2 and the signal is level-adjusted by a contour signal processing circuit 3 and inputted to a polarity selecting circuit 5. The polarity selecting circuit 5 inputs a control signal Sc having a specific minus voltage previously and outputs a signal S6 obtained by inverting the polarity of the contour signal S4. For the purpose, the opposite-polarity contour signal S6 is added to the input video signal S1 and a video output signal S7 which is decreased in the white level at the front and rear end parts is sent out. A line crawl results from that a signal S8 having different brightness is inputted in every horizontal period and when this signal S8 is inputted, a mixing circuit 4 mixes a signal S9 from a polarity selecting circuit 5 with the signal S8 to output a video output signal S10, so the line crawl is reduced.
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