Patent ID: 6438265
Filing Date: 2002-08-20
Classification: G06K

Abstract:
In an optical character recognition system wherein a scanned gray scale image contains text to be recognized in the form of strokes having a known stroke width corresponding to several image pixels, a method of binarization comprising: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, where the determining text pixels comprises, for each analyzed pixel, checking that either one of the differences between the value of said 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 with respect to the line row is greater than said relative threshold, which circle is centered at the location of said analyzed pixel and has a radius equal to said stroke width, subsampling the image at a rate corresponding to at least two pixels in order to detect kernels of text, and binarizing the image pixels only in tiles of several stroke width sides containing said text kernels by using in each of said tiles, an absolute threshold estimated in said tile.