| 摘要 |
PROBLEM TO BE SOLVED: To provide an image coder where the image quality and a higher compression rate are compatible by taking into account a visible characteristic of deterioration in the image quality due to lossy compression of image data. SOLUTION: The image coder is provided with an area separation means that separates image data into areas, a compression means that includes compression systems including lossless compression and lossy compression, and a compression system selection means that selects one compression system from the compression means. Since the compression system selection means adopts a selected compression system for each area and the compression means compresses the image data by using the selected compression system, areas with visibly conspicuous deterioration and areas with visibly inconspicuous deterioration are separated and lossless compression and lossy compression are selectively applicable to the areas. Thus, the image coder can be obtained, in which the visible characteristic of each area can sufficiently be taken into account and the high compression rate and the image quality are compatible.
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