IMAGE PROCESSOR, IMAGE FORMING APPARATUS, AND IMAGE PROCESSING PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide an image processor by which an image with successful graininess is obtained in comparison with an invention for judging which of a black core pattern and an all white pattern is generated based on a fixed threshold.

SOLUTION: The image processor 10 is provided with: a gradation value acquisition part 12a which acquires gradation values of noticing pixels sequentially selected as objects for binarization processing from input image data expressed by pixels of M (M≥3) gradations; and a pattern determination part 12b which determines painting out patterns of pixel groups of output image data corresponding to the noticing pixels according to compensated gradation values obtained by adding error values diffused from peripheral pixels to the gradation values of the noticing pixels. In the painting out patterns, a first pattern constituting a core of halftone dots, and a third pattern in which all the pixels are not substantially painted out, and the pattern determination part 12b determines the pattern to either of the first pattern or the third pattern according to magnitude relation between the corrected gradation values and the predetermined threshold which periodically changes.

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