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Pattern Orientation Scheme

IP.com Disclosure Number: IPCOM000092450D
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Gaffney, JE: AUTHOR

Abstract

In order to automatically recognize a pattern, such as a fingerprint, in a reproducible fashion, it is important that the pattern be oriented in the same direction each time it is scanned. In fingerprint recognition proper orientation of the print is particularly important.

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Pattern Orientation Scheme

In order to automatically recognize a pattern, such as a fingerprint, in a reproducible fashion, it is important that the pattern be oriented in the same direction each time it is scanned. In fingerprint recognition proper orientation of the print is particularly important.

A method which can be employed to obtain an orientation direction for a fingerprint, or similar pattern, is to determine the percentage of the ridges of the pattern which are oriented in each direction. When a plot is made of percentage- of-lines versus angle of the lines, this plot has certain characteristics depending on the fingerprint scanned. For a loop or arch fingerprint, it is a two-humped curve. For a whirl it is a single-humped curve. The desired orientation direction can be selected as the angle of one of the humps of a curve or as the angle of one of the valleys. Since the relative angle frequency remains constant for a given fingerprint, this method always provides a reproducible orientation direction.

A number of hardware or software methods can be employed to obtain the desired frequency versus angle plot. One of the best ways to obtain this plot is to project a Fraunhofer diffraction pattern of the fingerprint. The diffraction pattern is then scanned with a rotating slit. The result of this scan is the desired plot.

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