Patent ID: 6708884
Filing Date: 2004-03-23
Classification: G06K

Abstract:
A method for detecting an omnidirectional postnet bar code on an object by digital signal processing, comprising the steps of:acquiring a two-dimensional digital image of said omnidirectional postnet bar code, said two-dimensional digital image being represented by a plurality of color-coded pixels; filtering said two-dimensional digital image with a means for filtering to remove a plurality of non-black coded pixels from said plurality of color-coded pixels and provide a filtering output; saving said filtering output in a memory device; dilating said two-dimensional digital image to form a block dominated by a plurality of black-colored pixels; providing a down sampled image Gm; match-filtering said down-sampled image Gm with a set of two-dimensional matched filters to indicate a best-matched filter; determining a an omnidirectional postnet bar code location; associating a plurality of matched filters with an orientation angle of said omnidirectional postnet bar code; generating a plurality of coefficients from said match-filtering step during a feature template step; identifying a gravity center for each of a plurality of short bar codes and connecting said gravity centers to form a straight line; comparing said straight line with said omnidirectional postnet bar code location to generate a verification result; and detecting a position and an orientation of said omnidirectional postnet bar code location by matching said omnidirectional postnet bar code location with said verification result.