Apparatus and method for hybrid compression of raster data
US5982937A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 24, 1996 |
| Grant date | Nov 9, 1999 |
| Priority date | — |
| Expiry date | Dec 24, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T9/00
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
From a raster page, patches of connected pixels of the same color are identified. Patches of at least a predetermined sized, typically corresponding to text or line art objects, are subjected to a lossless compression. Patches below the predetermined size, typically corresponding to image or photo objects, are substantially subjected to a lossy compression. The patch predetermined size controls the mix of lossless and lossy compression procedures. Optimum compression is achieved by maximizing the lossless compression while attaining a targeted compression ratio. Various features include efficient recognition and encoding of patches, refined treatment of the boundaries between the lossless- and the lossy-compressed pixels, adaptive compression ratio control, and fail-safe compression provisions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.