摘要 |
A compressed image, for which a desired SSIM value is obtained, is acquired when irreversible compression is performed. Specifically, a quadratic curve G2 is defined. Next, a compression ratio P4 is calculated. An image is irreversibly compressed at the compression ratio P4, the compressed image is decoded and an SSIM value S5 is calculated. If the calculated SSIM value S5 is outside an allowable range of the target SSIM value, then the quadratic curve G2 is corrected in such a manner that it will pass through an intersection C4 between the compression ratio P4 and the SSIM value S5, whereby a quadratic curve G3 is obtained.
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