Multi-mode image processing permitting selection of quantization

Details Multi-mode image processing permitting selection of quantization Multi-mode image processing permitting selection of quantization

1992-03-20

1995-06-06

Ip, Paul

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

358404, 348395, 348405, 348420, H04N 146

Patent

active

054227364

ABSTRACT:
The present invention aims at an efficient encoding of image data while maintaining the quality of the image. It has been a conventional practice that coefficients obtained from DCT (discrete cosine transformation) are quantized using a single quantization table. If, however, an identical quantization is performed for images that are considerably dissimilar in their statistical characteristic, deterioration of image occurs especially at character portions where high frequency dominates. In the present invention, a statistical characteristic of a previous block is obtained and a suitable table is selected from a plurality of quantization tables to achieve improved image quality.

REFERENCES:
patent: 3984626 (1976-10-01), Mounts et al.
patent: 4691329 (1987-09-01), Juri et al.
patent: 4723129 (1988-02-01), Endo et al.
patent: 4723161 (1988-02-01), Koga
patent: 4797742 (1989-01-01), Sugiyama et al.
patent: 4862262 (1989-08-01), Tanaka
patent: 4887151 (1989-12-01), Wataya
patent: 5025482 (1991-06-01), Murakami et al.
patent: 5028995 (1991-07-01), Izawa et al.
patent: 5045925 (1991-09-01), Saito
patent: 5073821 (1991-12-01), Juri
patent: 5162923 (1992-11-01), Yoshida et al.
patent: 5184316 (1993-02-01), Sugiyama
patent: 5185655 (1993-02-01), Wakeland
patent: 5241401 (1993-08-01), Fujiwara et al.
patent: 5253054 (1993-10-01), Fujiwara et al.
patent: 5253075 (1993-10-01), Sugiyama

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