| 摘要 |
PROBLEM TO BE SOLVED: To perform reduction processing of a binary image, while faithfully reproducing density and keeping image quality. SOLUTION: On the basis of the reduction factor, binary image data are divided into plural blocks, respectively including one or plural pixels corresponding to the respective pixels of a reduced image (S11). In each of these plural blocks, the density value of a relevant block is determined, on the basis of the ratio of the number of on-pixels to the total number of pixels inside the relevant block (S13). On the basis of the determined density value, a binary pixel value to be assigned to the reduced pixel, corresponding to the relevant block is decided (S15). The (positive or negative) error of the density to be generated in the case of converting the density value used in this decision for a binary value is calculated, and this error is diffused to adjacent blocks (S16). Such processing is successively repeated for each of blocks. The diffused error is added to the density value of the block in the diffusion destination, and the pixel value is decided from the added density value. |
