Shu Chen Lin

US Patent:

6708884, Mar 23, 2004

Filed:

Jun 25, 2002

Appl. No.:

10/319670

Inventors:

Wei Su - Englishtown NJ
Yun-Qing Shi - Millburn NJ
Cheng-jyh Chang - Chung Ho, TW
Shu Lin - Indianapolis IN

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

G06K 710

US Classification:

23546209, 23546208, 23546202, 382101

Abstract:

A method for rapid and precise detecting of an omnidirectional postnet bar code on an object by digital signal processing is provided. In order to rapidly and accurately detect omnidirectional postnet bar codes, a two-dimensional digital image containing the postnet bar code is acquired, filtered and dilated to form a block dominated by a plurality of black-colored pixels. Then a down sampled image is provided and match filtered with a two-dimensional matched filtering output to indicate a best-matched filter, thus determining a postnet bar code location and orientation by associating matched filters with an orientation angle of the omnidirectional postnet bar code. The method further comprises the steps of identifying a gravity center for each short bar code and connecting the gravity centers to form a straight line by using a Hough transform and comparing the straight line with the postnet bar code location to generate a verification result and then detecting a position and an orientation of said postnet bar code location by matching said postnet bar code location with said verification result.