Transform coding using coefficient prediction techniques

Details Transform coding using coefficient prediction techniques Transform coding using coefficient prediction techniques

1989-10-12

1991-03-19

Kostak, Victor R.

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

358135, H04N 712

Patent

active

050015591

ABSTRACT:
A system and method for improving the quality of decoded images, without any cost to compression efficiency, in both progressive still frame and motion video applications wherein the images are coded with intraframe transform based coding techniques, such as Discrete Cosine Transform (DCT) coding. Prediction of the AC components is utilized and operations are performed on the AC coefficient prediction in the decoder portions of the system in combination with a thresholding technique. Input images are subdivided into blocks of pixels, which are changed into blocks of coefficients by forward transform coding resulting in DC coefficients, representative of the average value in a block of pixels, and AC coefficients, representative of harmonic frequencies from the block, whereupon the predicted coefficient values are thresholded and the thresholded coefficient values are added to their corresponding transform coefficient values for the given block. These steps are repeated for all of the blocks of the image and the image representation is recovered by applying an inverse transform operation to the results of all of the additions for all of the blocks of the image.

REFERENCES:
patent: 4707738 (1987-11-01), Ferre et al.
patent: 4725885 (1988-02-01), Gonzales et al.
"Prediction of AC Coefficients from the DC Values" International Organization for Standardization May '88; Niss IBM Journal of R and D; vol. 32, #6; pp. 717-795; Nov. '88.
Advances in Picture Coding; Musmann et al., IEEE Proceedings, vol. 73, #4; Apr. '85; pp. 523-548.

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