JPS55102967A - Half-tone reproduction system for facsimile or the like - Google Patents

Abstract

PURPOSE: To express clearly a gradation difference by obtaining an apparently- natural half-tone gradation difference by having n gradations reproducing half tones and then by generating black information and white information in different periods.

CONSTITUTION: An analog picture signal including half tones from picture signal input terminal 12 is converted by A/D converter 1 into an "n+1"-bit digital signal, which is synchronized by memory circuit 2 with clocks from basic clock signal input terminal 13 to divide it into a low-order n-bit output and high-order one-bit output, which are supplied to selector circuit 3. From this circuit 3, a half tone close to black and that close to white are selected and applied to adder circuit 6 and gate circuit 7, and assignment circuit 4 and selector circuit 5 add a fixed constant to circuit 6, whose output is compared with that of counter circuit 8 by comparator circuit 9. Then, a white signal of m pulses is generated, gradation by gradation, in different period on the basis of a black signal of n/2 gradations on the black information side and a black signal of m pulses is also generated, gradation by gradation, in different periods on the basis of an n/2-gradation white signal on the white information side, thereby obtaining a clear gradation difference.

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