JPS5567273A - Half-tone picture processing method - Google Patents

Abstract

PURPOSE: To reproduce well a minute pattern existing in the half-tone back-ground by reproducing it by composite signal between signals obtained by subjecting video signals to density modulation and signals obtained by subjecting video signals to binary quantization.

CONSTITUTION: Video signal S_i,_j is subjected to multilevel quantization by multilevel quantizing equipment 1 to obtain density at every address and is subjected to the processing utilizing dither matrix. This operation is performed by giving clock signals to a counter to shift successively designation addresses of dither matrix T to be stored in a memory. T(k,l) and the density of the picture element at address (i,j), which are obtained here, are compared with each other by a comparator, and black and white are defined for density (i,j)≥T(k,l) and density (i,j)>T(k,l) respectively. Meanwhile, binary quantizing equipment 6 sets a prescribed threshold level and defines a higher level as black. The signal of quantizing equipment 6 and the signal of half-tone generator 5 are inputted to operation circuit 7, and OR between them is operated to indicate output signal "1" or "0" as black or white. Thus, a picture where a gradation picture and a linear picture are mixed cen be reproduced well.

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