System and method for recompressing a jpeg image using requantization

摘要

A system and method for recompressing a JPEG image using requantization is described. DCT transform coefficients for a compressed JPEG image are statistically analyzed to generate a stored numeric error representation. Local minimizers are determined from the stored numeric error representation with selective rounding. A new quantization matrix Q1 is selected from the local minimizers bounded by a target quantization matrix Qbound. The compressed JPEG image is recompressed using the new quantization matrix Q1.