| 摘要 |
PURPOSE:To obtain a picture with excellent quality, by approaching a value corresponding to a counted value of a binary-coding comparator output sequentially to an objective value by using a sequential comparison circuit, and setting a coincident threshold value to cope with change in contrast and noise. CONSTITUTION:An output signal from a CCD image sensor 11 and an analog signal converted from a digital slice level at a D/A converter 16 are fed to a comparator 12, and its output is supplied to a picture processor as a sliced binary-coded signal. The output is branched to a counter 14 and the counted value is fed to the sequential comparator circuit 15. A reference value being the ratio of the length of the pad to that of board is set to the circuit 15 according to the scanning range L in advance. The ratio of the length of the pad to that of the board is obtained from the counted value at one scanning from the counter 14, and the slice level is changed so as to be made coincident with the reference value and the output is set to a D/A converter 16. |
