| 摘要 |
A supercell is divided into halftone dot cells each with a highlight point at center and halftone dot cells each with a shadow point at center. Thresholds 0, 1, 2, 3, . . . assigned to pixels in the halftone dot cells each with a highlight point at center and thresholds N, N-1, N-2, N-3, . . . assigned to pixels in the halftone dot cells each with a shadow point at center are alternately determined, i.e., determined in the order of 0->N->1->N-1->, . . . ->3->N-3. When the density of an original image is high, the number of blackened pixels in the halftone dot cells each with a highlight point at center and the number of blank pixels in the halftone dot cells each with a shadow point at center are equalized to each other, thus preventing moire stripes from being produced which would otherwise be caused by a periodic change in the number of blackened pixels in the halftone dot cells.
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