| 摘要 |
PURPOSE:To obtain a proper binarization signal even to an image signal having a slope in a period by dividing the image signal of one line into plural sections, using a peak level at each section as a reference and using the peak level of an adjacent section so as to apply correction, thereby generating a slice level. CONSTITUTION:A control circuit 4 divides the image signal of one line into n-period and a white bit in each section is counted by counters 3-1-3-n. Each counter counts white bits having preset bit number or above and the control circuit 4 recognizes the relation of vertical level between the image signal A and the slice level D in each section, sets the level again at every section and gives the result to a D/A converter 5. In repeating the operation above, the control circuit 4 recognizes the peak value level of the image signal A in each section, the peak value level in the said section and that at right adjacent period are compared, the level is decreased at a rate based on the lower level and the signal B of a prescribed level in the period is fed to the D/A converter 5. When effective read is started, the control circuit 4 drives an integration circuit 6 and the result is fed to the comparator 2 as a waveform D being the integration of the slice level B.
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