Document image thresholding using foreground and background clustering
US6044179A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 26, 1997 |
| Grant date | Mar 28, 2000 |
| Priority date | — |
| Expiry date | Nov 26, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06V30/10
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Document image thresholding using foreground and background is disclosed. A document (16) is scanned and a region (30) and a sub-region (32) of the document is selected. The intensity value of a pixel in the region is compared to an average intensity value of pixels in a foreground cluster and to an average intensity value of pixels in a background cluster (50). The pixel is assigned to the foreground cluster (53) if the intensity value of the pixel is closer to the average intensity of the foreground cluster, or to the background cluster (54) if the pixel intensity is closer to the average intensity value of the background cluster. A new average intensity value is calculated for the foreground cluster (55) and the background cluster (56). A new pixel is compared to the new average intensity values for the foreground and background clusters and the process is repeated until all pixels in the region have been compared (57). A threshold value is computed (62) based on a function of the average intensity value of pixels in the foreground and background cluster. Each pixel in the sub-region is then converted to a white pixel if the pixel intensity level is greater than the threshold va…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.