System and method for recompressing a jpeg image using...

Details System and method for recompressing a jpeg image using... System and method for recompressing a jpeg image using...

2005-02-01

2005-02-01

Tran, Phuoc (Department: 2621)

Image analysis

Image compression or coding

Quantization

C382S250000

Reexamination Certificate

active

06850650

ABSTRACT:
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 Q1is selected from the local minimizers bounded by a target quantization matrix Qbound. The compressed JPEG image is recompressed using the new quantization matrix Q1.

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Reininger RC et al., “Distributions of the Two-Dimensional DCT Coefficients for Images,”IEEE Trans. On Comm.,vol. COM-31, No. 6, pp. 835-839, Jun. 1983, IEEE Press.
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Chan S, “Recompression of Still Images,”Tech, Rep.2-92, University of Kent, 41 pps., Mar. 1992, Kent, England.
Lam Ey et al., “A Mathematical Analysis of the DCT Coefficient Distributions for Images,”IEEE Trans. On Image Proc.,vol. 9, No. 10, pp. 1661-1666, Oct. 2000, IEEE Press.

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