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System and method for determining block direction in fingerprint images
| Details |
Inventors: Jain, Anil K.; Hong, Lin; Bolle, Rudolf Maarten; Pankanti, Sharathchandra Umapathirao;
Assignee: International Business Machines Corporation (Armonk, NY)
Primary Examiner: Bella; Matthew C.
Assistant Examiner: Chawan; Sheela
Attorney, Agent or Firm: Percello; Louis J. Perman & Green, LLP
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. |
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DETAILED DESCRIPTION The present invention is a system and method for determining an optimal block size in an area of an image, e.
g.
, a fingerprint image, to obtain a reliable estimate of image pixel (fingerprint ridge) orientations, and block orientations, within the given block.
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.
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Image Analysis 
