| 摘要 |
PROBLEM TO BE SOLVED: To improve image compression efficiency by providing a block size change means for changing a specified size by a blocking means corresponding to the ratio of a block replaced with specified information by an image processing means or the like. SOLUTION: Image information fetched by data fetch (S10) is blocked by a prescribed standard size (block size composed of 8×8 pixels for instance) (S11) and the processing of two rows is performed so as to compute a block kind and a data amount within the block (S12). When the arithmetic processing of the two rows is ended (S12; Y), an omission block rate is summed up (S13). In the case that the omission block rate exceeds 20% (S14; Y), the block size is changed from the standard size of 8×8 pixels to the enlarged size of 16×16 pixels for instance (S15). Then, by appropriately changing the block size at the time of performing blocking corresponding to the fluctuation state of the image density of a pixel block, a compression parameter is optimized corresponding to the fluctuation state and compression efficiency is improved.
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