| 摘要 |
PROBLEM TO BE SOLVED: To compensate variation in density of an output image concurrent environmental variation, related to an image forming apparatus that forms a gradation image in binary in pseudo manner. SOLUTION: A steady threshold table for compensating maximum density corresponding to a steady condition, a maximum density compensating threshold table 1 for making the maximum density higher, and a maximum density compensating threshold table 2 for making the maximum density further higher, are prepared in a threshold table storing part 200. A threshold processing part 220 binarizes an image data indicating a multiple tone image by using the threshold table selected by a table selecting part 210. The table selecting part 210 selects the steady threshold table for compensating maximum density corresponding to the steady condition, as an initial setting. When it is detected that variation in concentration is caused, the table selecting part 210 selects what has a tendency to maintain visual maximum density out of the threshold tables stored in the threshold table storing part 200, corresponding to the variation in density indicated by density information, to input to the threshold processing part 220. COPYRIGHT: (C)2003,JPO
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