| 摘要 |
PROBLEM TO BE SOLVED: To enable high speed conversion by permitting plural one-row patterns generated by continuing respective rows in plural horizontal directions in a dither pattern having a fixed number of pixels in row and column directions to continue in a longitudinal direction by means of a number corresponding to the number of the rows of the pixels in the dither pattern and, then, executing a dither processing through the use of the list of plural kinds of generated rectangular pattern. SOLUTION: When an image is converted into VRAM data by using the dither pattern, the respective rows of the dither pattern are continued so that the rectangular dither pattern is generated by a dither generating module 7. Besides, the list of the dither pattern is generated by continuing the patterns for the portion of the height of the dither and stored in a cache memory 6. The dither processing is executed not at every one pixel but by rectangular dither pattern unit corresponding to a color level from the list. Thus, the image conversion is executed at high speed in the case the dither processing is executed against each color pixel.
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