| 摘要 |
<p>PROBLEM TO BE SOLVED: To use both of an arrangement of a threshold of a dither mask and image data because of a relationship between them, although half-tone processing using a dither mask has an advantage that various characteristics can be given to the dither mask.SOLUTION: A first threshold aligned on a dither mask is compared with a corresponding gradation value associated with image data. When it is determined that the corresponding gradation value exceeds the first threshold, dot data is created. When it is determined that the corresponding gradation value does not exceed the first threshold, an error diffusion method is applied, so as to create the dot data by comparing corrected data in which an error is diffused to the image data with a second threshold. In any case, an error caused as a result of the dot data is diffused to pixels in a predetermined circumferential range. According to how the corresponding gradation value is set to original image data, a dither method and an error diffusion method can be freely combined.</p> |
