Method and apparatus for block coding vertical mode codes for enhanced compression of image data
US4794461A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 10, 1986 |
| Grant date | Dec 27, 1988 |
| Priority date | — |
| Expiry date | Sep 10, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4175
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for improving the performance of data compression processes, such as relative address coding, CCITT standard facsimile processes, and similar two-dimensional image coding processes, by block coding one or more of the vertical mode codes produced by these processes. The performance of data compression processes is improved by representing one or more sequences of vertical mode code words with a single block code word. A reference scan line is preferably selected from among a plurality of previous scan lines, for example, the immediately preceding ten scan lines, for two-dimensional image coding. The previous scan line which is most similar to the current scan line to be coded is selected as the reference scan line. The selected reference scan line is then fed with the current scan line to be coded to a two-dimensional data compression coding process so as to yield a first tier of data compression. The image data are preferably checked during the two-dimensional data compression coding process for a predetermined run of a given vertical mode code, and a preselected block code is substituted if the predetermined run of the given vertical mode code appears so as …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.