| 摘要 |
PURPOSE:To obtain the most suited reproduced picture, even if the contrast of an original is changed, by storing a picture signal in an analog register to detect the maximum/minimum levels, and making binarization through the voltage divided value taken as a threshold value. CONSTITUTION:An analog picture signal having levels according to the contrast of an original is inputted to the input terminal of an analog shift register 14 from an input terminal 13. Shift clocks are fed to the clock terminal of the shift register 14 from a terminal 15, and a picture signal inputted to the shift register 14 is sequentially transferred. Further, a maximum level is outputted at a terminal 17 of a level detection circuit 16 and a minimum level is outputted to a terminal 18, and the level of the output of an output terminal 25 of a voltage dividing circuit 24 is always at an intermediate level, even if the picture signal is greater or smaller. The picture signal picked up from an intermediate tap 1i of the shaft register 14 is binarized by a comparator 28 by taking this intermediate level as a threshold value. |
