06289112 is referenced by 327 patents and cites 10 patents.

A reliable estimate of image pixel (fingerprint ridge) orientations, and block orientations for a given block is determined by finding an optimal block size in an area of an image, e.g., a fingerprint image. An initial block size is chosen. Then a block direction is determined, e.g., by analyzing intensity gradients in two directions, preferably two orthogonal directions, at a plurality (preferably all) of the pixels locations in the block. Block directions of blocks in a given area of the images (fingerprint) are compared. If the compared directions are within a tolerance of one another, the determined direction of the block is considered correct. However, if the compared directions are not within a tolerance of one another, the block size is changed and the process is repeated.

Title
System and method for determining block direction in fingerprint images
Application Number
9/30438
Publication Number
6289112 (B1)
Application Date
February 25, 1998
Publication Date
September 11, 2001
Inventor
Sharathchandra Umapathirao Pankanti
Mt. Kisco
NY, US
Rudolf Maarten Bolle
Bedford Hills
NY, US
Lin Hong
Lansing
MI, US
Anil K Jain
Okemos
MI, US
Agent
Perman & Green
US
Agent
Louis J Percello
US
Assignee
International Business Machines Corporation
NY, US
IPC
G06K 9/00
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