Patent ID: 6370271
Filing Date: 2002-04-09
Classification: G06K

Abstract:
A method for detecting a pattern in an input image, comprising:generating from the input image digital data defined by a plurality of rows of pixels, each pixel defined by an N-bit value; processing 12 or fewer rows of pixels one row at a time, each row containing at most 100 pixels, by obtaining a row of pixels, thresholding the N-bit value of each pixel in that row to an M-bit value where Mperforming a specified element finding procedure on the processed rows of thresholded digital data stored in the buffer to determine if at least a portion of the specified element is present in the stored digital data, wherein the specified element is a geometric shape that forms a part of the pattern; and if it is determined that at least a portion of the specified element is present in the stored digital data, performing the following steps: calculating coordinates of a particular characteristic of each specified element, at least a portion of which is identified in the stored digital data, and storing the calculated coordinates in a list; generating a density template for each specified element for which coordinates have been calculated by partitioning an area of the stored digital data containing that specified element including an interior thereof into a plurality of sectors and maintaining a density count for each sector; and performing template matching for each specified element for which a density template has been generated to determine if that density template substantially matches a corresponding reference pattern density template.