| 摘要 |
PURPOSE:To repeat a high resolution image having an optimum gradation without fail by modifying a dither matrix corresponding to the various density of image data outputted from an image reading means. CONSTITUTION:In order to specify L1 among dither matrices L1-L4 stored in a ROM5, address data i, j (=1) is transmitted to the ROM5. Then, when a scanner 1 starts reading of an original, analog data inputted to a sampling/ quantizing circuit 2 is converted into a digital multivalued signal. When a four picture element average density measuring circuit 7 decides the various density through density average calculation of one block, and a level data (n), for instance, '01', for deciding the dither matrix stored in the ROM5 is transmitted to the ROM5, the dither matrix L1 is selected and set in a comparator 4. Simultaneously the average density measuring circuit 7 transmits a pulse signal for specifying a density level to a laser drive circuit 6. Then the judgement is made whether or not the address data j is set to '4'. Then such an action is repeated to terminate the control.
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