Precise Biometrics White Paper
Precise BioMatchTM
Jerker Bergenek, Magnus Pettersson
Precise Biometrics AB, Dag Hammarskjölds väg 2, SE 224 67 Lund, Sweden
31st October 2001
Abstract
Precise Biometrics uses a proprietary algorithm for fingerprint matching. The
main reason is to ensure higher security. This white paper explains the benefits
and advantages with the method.
1
Introduction
Precise BioMatchTM , is an algorithm to match fingerprint images optimized for
security and one to one match. Precise Biometrics developed the method, as
the existing minutiae based algorithms were not considered secure enough. In
contrast to minutiae based algorithms, this method is not developed for identification of criminals, but for computer and mobile security. The goal with Precise
BioMatchTM is to include as many fingerprint characteristics as possible and
to make the critical verification process less time consuming. It is also desired
that the algorithm should be less dependent on the size of the fingerprint sensor.
Another goal is to be independent of the minutiae complexity, such as being dependant on a minimum number of minutiae points in a fingerprint to perform a
match. Precise BioMatchTM also lacks the difficulties in finding minutia points as
fingerprint quality varies. This paper will first explain minutiae based matching
followed by Precise BioMatchTM .
2
Minutia matching algorithm
Every fingerprint consists of a number of ridges and valleys. Ridges are the upper
skin layer segments of the finger and valleys are the lower segments. The ridges
form so called minutia points; ridge endings - where a ridge ends - and ridge
bifurcations - where a ridge splits.
c 2001 Precise Biometrics AB. All rights reserved
°
Precise BioMatchTM
2
Figure 1: Enrolment of minutia points.
At the registration step - the enrolment - the minutia points are located (figure
1). The relative positions to each other and their directions are recorded. This
data forms the template, the information later used to authenticate a person.
At the matching stage (figure 2), the incoming fingerprint image is preprocessed and the features are extracted. The features are compared with the
registered template, trying to make as many minutia locations as possible to coincide within a certain boundary. The result of the matching is usually the number
of matching minutiae. A threshold is then applied, determining how large this
number shall be to pass the authentication.
Figure 2: Verification with minutia points.
3
The Precise BioMatchTM algorithm
The patented Precise BioMatchTM solves the authentication problem from another angle. Instead of registering the minutia points, small images and their
relative distances are extracted from the fingerprint (figure 3). These images are
chosen to maximize the amount of unique information that is recorded. The area
around a minutia point can be such an area, but also areas with for example a
low curvature radius, the main structure or an unusual ridge combination can be
chosen.
Precise Biometrics AB
White Paper | 31st October 2001
Precise BioMatchTM
3
Figure 3: Enrolment with Precise BioMatchTM .
The verification procedure (figure 4) begins with the pre-processing of the
incoming fingerprint image. The registered small images from the template are
then correlated in the image, trying to find areas that are identical. The match
result contains information on how well the stored small images fitted the verification image. A threshold describing the smallest fraction allowed is then used
to decide if there is a match or not.
Figure 4: Verification with Precise BioMatchTM .
Precise Biometrics AB
White Paper | 31st October 2001
Precise BioMatchTM
4
Advantages with Precise BioMatchTM
• Low FAR (False Acceptance Rate)
• Low FTE (Failure To Enrol), no need to locate minutia points.
• Easy implementation in hardware gives a cost efficient solution
• Ideal for embedded solutions (Precise BioCoreT M )
• Smaller sensors can be used because of the large amount of information stored, enabling mass deployment
• Fast algorithm even on 8 bit processors (Match-On-Card)
Precise Biometrics AB
White Paper | 31st October 2001
Precise BioMatchTM
5
For Additional Information
www.precisebiometrics.com
Sweden, Lund
Precise Biometrics AB
Dag Hammarskjlds v.2
SE 224 64 Lund
Sweden
Tel: +46 46 311 100
Fax: +46 46 311 101
E-mail: info@precisebiometrics.com
Sweden, Stockholm
Precise Biometrics AB
Box 1223
SE 164 28 Kista
Sweden
Tel: +46 8 514 426 55
Fax: +46 8 514 426 56
E-mail: info@precisebiometrics.com
USA, Washington
Precise Biometrics Inc.
8300 Boone Boulevard, Suite 500
Vienna, VA 22182
USA
Tel: +1 703 848-9266
Fax: +1 703 832-0577
E-mail: infous@precisebiometrics.com
c
Entire contents °2001
by Precise Biometrics AB. All rights reserved. Reproduction of this publication in any form without prior written permission
is forbidden.
Precise Biometrics AB
White Paper | 31st October 2001