| 摘要 |
PROBLEM TO BE SOLVED: To obtain various types of dither matrixes by flexibly changing the size of a dither matrix through suppression of the capacity of the dither matrix table of the gradation changing section of a printer. SOLUTION: Matrix sizes at every printing color are written in size-setting registers 13 and 17. The valves which decide the addresses of the dither matrix table to be referred to from original gradation data are set in start address setting registers 12 and 16. The start addresses of the registers 12 and 16 are preloaded in M-ary counters 15 and 19. Comparators 14 and 18 reset the counters 15 and 19, when the output addresses of the counters 15 and 19 become equal to designated size values. An address combining section 20 generates a dither matrix from the output addresses of the counters 15 and 19. The threshold data in a dither matrix table storing section 21 are selected, based on the dither matrix addresses. A data comparing section 22 generates platting data having changed gradation values by comparing threshold data with original threshold data.
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