| 摘要 |
PROBLEM TO BE SOLVED: To keep a sufficient resolution for characters/line drawing images and keep a sufficient tone reproduction for photographic images for performing multi-level dither processing and to suppress transient discontinuity in the boundary of an image to sufficiently secure the continuity of the image across the boundary. SOLUTION: It is discriminated by an image area separation part 45, whether input gradation image data are in a character/line drawing area or a photographic image area. When it is discriminated that this data are in a character/ line drawing area, a pseudo-halftone processing part 44 selects a multi-level dither threshold array, capable of keeping resolution to perform the pseudo- halftone processing, but if it is discriminated that this data are in a photographic image area, the pseudo-halftone processing part selects a multi-level dither threshold array, capable of keeping the gradation to perform the pseudo halftone processing.
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