String-match array for substitutional compression
US5930790A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 25, 1997 |
| Grant date | Jul 27, 1999 |
| Priority date | — |
| Expiry date | Sep 25, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99942
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A circuit for implementing a substitutional compressor. Comparators compare a current input pixel against a large number of previous pixels, the "history", stored in a series of shift registers. Each register and associated comparator constitutes a cell. If one or more matches are found the history data is shifted one pixel, the non-matching cells are disabled, and the next input pixel is compared against the contents of the same cells that had the previous matches. The matching is terminated when the longest series of matching pixels is found. The output code is then the length of the matching series of pixels, and the displacement of the first input pixel from the first matching pixel. An encoder generates an initialize signal that resets all of the disabled cells on the same clock cycle on which the output code word is generated. To make the circuit more compact, the cells can be arranged into a square format with one output line for each row and column from the cells to the encoder.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.