Automatic document image revision
US5020122A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 10, 1989 |
| Grant date | May 28, 1991 |
| Priority date | — |
| Expiry date | Mar 10, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/40093
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A system for electronically storing revisions or modifications to documents which are already electronically stored in unrevised or unmodified form. The system compares, at the pixel-by-pixel level, a modified document bit map with a stored document bit map and determines from the differences between the two bit maps, at the pixel-by-pixel level, which differences are significant and which are insignificant. A revised document bit map is then formed from the portions of the stored-document bit map exhibiting no significant bit map differences and the significant differences bit map. The result is a revised document bit map in which no unnecessary changes have been introduced into the initial stored-document bit map. The system also includes steps for defining, on a pixel-by-pixel basis, a significant region bit map from the significant difference bit map and for forming the revised document bit map using the significant region bit map.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.