| 摘要 |
PURPOSE:To reproduce a single thin line and a high-density pattern with a high space frequency by composing a binary coding circuit of a peak holding circuit which holds the peak value of an image signal, two comparators which convert an analog signal into a binary signal and have different slice levels, two slice level generation parts, an image signal comparing circuit, and a selector. CONSTITUTION:An image signal read by an image pickup element 10 is amplified by an amplifier 1 to a specific level. The amplified image signal is led to the peak holding part 2 and comparators 3a and 3b. The peak holding part 2 holds the peak value of the image signal and the peak level is divided to generate slice levels S1 and S2, which are used as reference voltages of the comparators 3a and 3b. Consequently, the output of the comparator 3a is as shown by (a) and the output of the comparator 3b is as shown by (b). Those signals (a) and (b) are compared with each other to select (a) when (a) and (b) are equal, (b) when (a) and (b) are different and (a) is at 'H', or (a) when (a) is at 'L'. Consequently, the signal (a) at a part A, the signal (b) at a part B, and the signal (a) at a part C is selected to obtain (c), thereby reproducing both the high-density pattern and thin line.
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