Half-tone image reproduction method and apparatus using partial density

Abstract

A half-tone image reproduction apparatus, which comprises a Dither matrix memory, constituted by a plurality of elements, for storing a multi-level Dither matrix having multi threshold levels assigned to the individual elements, input data supplying means for supplying the element on the Dither matrix and an input density level, and print dot forming means for forming print dots in accordance with the energy control level selectively read out from the Dither matrix memory. The energy control level stored in the Dither matrix memory is set in accordance with rules for changing the energy control level in accordance with a change in input density level. These rules are independently suitably determined for the respective partial density ranges which constitute a whole density range for the input density. According to this invention, gradation jump and deformation at a high density region can be prevented so that a half-tone image with smooth gradation and high resolution can be attained.