Image analysis – Image compression or coding – Quantization
Patent
1993-07-22
2000-04-25
Bella, Matthew
Image analysis
Image compression or coding
Quantization
348405, G06K 938
Patent
active
060553391
ABSTRACT:
A video data compression system is described utilizing frequency separation and quantization. The video data is separated into primary frequency components (components 4, 5, 6) and secondary frequency components (components 0, 1, 2, 3). The primary frequency components undergo fewer frequency separating stages (N>M) than the secondary frequency components. The quantization step width (Q.sub.1, Q.sub.2) applied to the differing primary and secondary components is varied in dependence upon the relative human visual responsiveness (R(f.sub.s)) to the spatial frequency (f.sub.s) represented by that component. In addition, those frequency components that have undergone fewer frequency separating stages are subject to a larger quantization step width than the other frequency components since the fewer frequency combination stages such frequency components will subsequently undergo has the result that the image degradation introduced by quantization is less noticeable. The system also includes entropy encoding (42) using selectable complementary encoding and decoding tables. The system is particularly applicable to recording and reproducing apparatus.
REFERENCES:
patent: 4780761 (1988-10-01), Daly et al.
patent: 5214502 (1993-05-01), Stone et al.
patent: 5268905 (1993-12-01), Soloff et al.
patent: 5291282 (1994-03-01), Nakagawa et al.
Bella Matthew
Frommer William S.
Sony United Kingdom Limited
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