Method of binarization in an optical character recognition system
US6438265B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 12, 1999 |
| Grant date | Aug 20, 2002 |
| Priority date | — |
| Expiry date | May 12, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06V30/10
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method of binarization used in an OCR system involves in determining text pixels by checking, for each pixel, that the difference between its value and the values of a plurality of pixels located at a predetermined distance therefrom is greater than a relative threshold corresponding to the difference in intensities between the text and the background of the image, subsampling the image at a rate corresponding to at least two pixels in order to detect kernels of text, and then binarizing the image pixels only in tiles of several stroke width sides containing text kernels by using in each tile, an absolute threshold estimated in that tile. The determining of text pixels includes, for each analyzed pixel, checking that either one of the differences between the value of the analyzed pixel and the value of the two pixels located at each intersection of a circle with each one of the row line, column line and both lines at the angle of 45 degrees, is greater than the relative threshold where that circle is centered at the location of the analyzed pixel and has a radius equal to the stroke width.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.