| 摘要 |
PURPOSE:To make the proper quantity of light incident from an object by detecting the abrupt fluctuation of high brightness of a video signal. CONSTITUTION:The video signal (a) is supplied to an arithmetic unit 3 through a delay line 2 for setting a time from an input terminal 1, and to a low pass filter 4, The low pass filter 4 filters a low frequency component (b) from the incoming video signal (a) and supplies to the arithmetic unit 3. The arithmetic unit 3 subtracts the low frequency component (b) from the incoming video signal (a) to generate a difference signal (c) and outputs to a slice circuit 5. The slice circuit 5 slices the incoming difference signal (c) at a prescribed level to generate a signal (d) and outputs to a peak hold circuit 6. The peak hold circuit 6 has a peak hold time, for instance, a several frame period, detects the peak value of the incoming signal (d), holds this peak value level and outputs to the non-inverse input terminal of an arithmetic amplifier 7.
|
