Method and apparatus for compressing mixed text and image data
US5832126A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 3, 1996 |
| Grant date | Nov 3, 1998 |
| Priority date | — |
| Expiry date | Jul 3, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/41
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
To convert a mixture of text data and dot-mapped image data to compressed dot-mapped data not exceeding a given size, the text data are converted to dot-mapped data, then losslessly compressed, after which the dot-mapped image data are down-sampled as necessary. To compress dot-mapped data to within a given size, lossless compression, lossy compression, and down-sampling followed by compression are attempted until the necessary size reduction is achieved. To convert a page of object data to compressed dot-mapped data, the objects are classified and prioritized, then rasterized and compressed by different methods according to their priorities. The compression ratios are predicted and monitored, and the compression parameters are modified according to the prediction error.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.