IMAGE PROCESSING DEVICE, AND COLOR IMAGE PROCESSING DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent deterioration in gradation reproducibility due to occurrence of irregular density, lines or the like caused by the output accuracy of an output device such as a printer. SOLUTION: With respect to the image processing device by which input gradation image data of 256-step gradation per 1 pixel are subjected to dither processing by using a reference threshold arrangement by a dither processing means and are converted into output image data of 8-step gradation per 1 pixel and an image is output by a printer, the printer has a different output accuracy between the horizontal scanning direction and the vertical scanning direction and the dither processing means has threshold arrangement characteristics which are locally non-periodic in a region of relatively medium to high gradation within a specified threshold range and sets a reference threshold arrangement in such a way that the output accuracy of the printer has non-isotropic threshold arrangement characteristics by which dots are linked together in preference and are grown in sequence in the scanning direction in which the output accuracy of the printer is relatively low. COPYRIGHT: (C)2009,JPO&INPIT