| 摘要 |
PROBLEM TO BE SOLVED: To prevent the quality degradation of contone images, even in the case that bitone images and the contone images coexist by dividing images into plural small areas, encoding the image information of the divided small areas, storing it in a bit group and sweeping out the bit group from a memory to a display output part after encoding it. SOLUTION: A bitone image 1 and a contone image 2 are separated from the information of a page description language sent from a host computer. In the bitone image 1 of characters and linear graphics, etc., since it is not required to express tones, information is converted into information of 1 bit per pixel. In the contone image 2 of the image of photographs and pictures, etc., since the tones are expressed, it is converted into the information of K bits per pixel. In order to distinguish the two kinds of the images, one page is divided into the rectangular areas of vertical M pixels and horizontal N pixels size and attribute bits are supplied in one-to-one correspondence with the pixels inside the rectangular area.
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