| 摘要 |
PROBLEM TO BE SOLVED: To provide a contrast adjustment device which is not affected by noise, overshoot, and a video maximum part and a video minimum part in a small area part of a video signal. SOLUTION: An automatic contrast adjustment device 1 which has a video amplifier 11 for adjustment of the contrast of an input video signal and an A/D converter 12 for conversion of the output of the video amplifier 11 to a digital signal is provided with a frequency discrimination means 17 which discriminates the type of the input video signal, a low pass filter 14 which varies, in correspondence with the discrimination result from the frequency discrimination means 17, the characteristics which remove a high frequency component included in the output video signal of the video amplifier 11 a maximum value detection means 15 which detects the maximum value of the video signal passing the low pass filter 14, and a maximum value discrimination means 16 which compares the maximum value of the video signal from the maximum value detection means 15 with a prescribed reference level and generates a signal for adjusting the contrast of the video amplifier 11 in accordance with the discrimination result.
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