US 6,983,065 B1
Method for extracting features from an image using oriented filters
Yusuf Akgul, Northboro, Mass. (US); Ivan Bachelder, Newton, Mass. (US); Prabhav Morje, Natick, Mass. (US); Juha Koljonen, Needham, Mass. (US); and Jason Davis, Bellingham, Mass. (US)
Assigned to Cognex Technology and Investment Corporation, Mt. View, Calif. (US)
Filed on Dec. 28, 2001, as Appl. No. 10/34,066.
Int. Cl. G06K 9/00 (2006.01)
U.S. Cl. 382—141 27 Claims
OG exemplary drawing
 
1. A method of detecting defects in an object comprising the steps of:
acquiring a digital image of said object;
applying a set of oriented filters to said digital image to generate a corresponding set of filtered data, wherein said set of oriented filters comprise two dimensional oriented spatial bandpass filters having incremented angles of orientation between each of said filters; and
combining said set of filtered data to form a combined data set representing defect features, wherein said combining step further comprises the steps of:
evaluating a response of each pixel in said image to each filter,
selecting a maximum response for each pixel and recording the angle of said filter to which said maximum response was related, and
associating said maximum response and said angle with its respective pixel for each pixel in said image.