Image compression encoding and decoding method and apparatus therefor
US5533138A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 9, 1994 |
| Grant date | Jul 2, 1996 |
| Priority date | — |
| Expiry date | May 9, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/146
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Television images to be digitally recorded are divided into blocks and the discrete cosine transform DCT of each block is taken. The DC coefficient of each DCT block is scalar-quantized, and its AC coefficients are classified-vector-quantized (CVQ). The square of the value that part or all the AC coefficients among horizontal AC coefficients including a first AC coefficient and vertical AC coefficients including a second AC coefficient, according to the zigzag scanning sequence of DCT block, are subtracted from a representative value of a preset reference class. Using a multilevel compression method, lowest level codes are vector-partitioned by P-units at equal intervals with respect to each classified DCT block, and code books of representative vectors corresponding to the partitioned vectors are provided. Indices of corresponding representative vectors in respective code books and the classified codes are taken as encoding data corresponding to AC coefficients to keep a constant number of bits in the lowest level codes. Then, errors created in a preceding level are corrected. Code books of S-units of representative vectors corresponding to the errors are provided again, and corre…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.