Method of encoding high resolution edge position information in continuous tone image information
US6020979A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 23, 1998 |
| Grant date | Feb 1, 2000 |
| Priority date | — |
| Expiry date | Mar 23, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4056
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method of encoding higher resolution edge information in lower resolution image information, so that the advantageous properties of both types of data can be used in binarization including the steps of receiving text/line art regions of the document image as binary pixels at a text/line art frequency selected to avoid aliasing effects at any edge pixels therein; receiving pictorial regions of the document image as continuous tone pixels, at a frequency lower than the text/line art frequency; applying an anti-aliasing filter to the text/line art regions, to replace some edge pixels with gray level pixels having M levels; converting the document image to a binary representation by converting each of the M levels in the text/line art regions to a binary representation reflecting correct edge position of the text/line art regions, and converting the contone pixels to a binary representation determined by a halftone pattern having N levels selected for the contone pixels.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.