| 摘要 |
PROBLEM TO BE SOLVED: To improve the image quality of a hatched pattern of low density in the case of performing image processing by using a dither matrix method. SOLUTION: A square dither matrix of 2n rows×2n columns is used, the square dither matrix is divided into four square matrices DM1 to DM 4 of 2n-1 rows×2n-1 columns respectively, the prescribed number of thresholds are spread over the divided matrix DM1 in the order of a size so as to cover it vertically, horizontally and diagonally, the DM1 over which the thresholds are spread is turned to 180 deg., 90 deg. and 270 deg. respectively, and the thresholds are spread over the DM2 to the DM4. Then, the image quality of a hatched pattern of low density is improved by comparing every threshold of each matrix DM1 to DM4 with the pixel unit density of an original image, deciding the on end off of every dot in accordance with the comparison result and reproducing the original image.
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