| 摘要 |
PURPOSE:To improve the resolution and to simplify a circuit constitution by providing a picture signal correcting converting means corresponding to a 'level- vs.-density characteristic' of the prescribed input picture signal at the front step of the comparator generating the binarization picture signal. CONSTITUTION:The picture signal of the original is inputted to a nonlinear characteristic amplifying circuit 1. To the circuit 1, a nonlinear characteristic is given which operates so that the level of a 'signal of a black side' in the picture signal to which the terminal is inputted can be relatively extended in comparison with the level of a 'signal of a white side', and the picture signal outputted from the circuit 1 through the characteristic is corrected gradiently in the area with a high density and inputted to a comparator 2. At the comparator 2, through the prescribed slice level, the above-mentioned gradient-corrected picture signal is binary-coded and outputted from a terminal 53. In such a case, in the circuit 1, to respective types of the inputted picture signal, plural gradient-correctable nonlinear characteristics are suitably held, thereby, the effective gradiation correction can be executed for all originals, etc.
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