Characteristic and Necessary Minutiae in Fingerprints

TL;DR

This paper models fingerprint minutiae as a superposition of stochastic point processes, distinguishing between necessary minutiae near singularities and characteristic minutiae, and uses Bayesian inference to analyze their patterns for fingerprint identification.

Contribution

It introduces a novel stochastic model for fingerprint minutiae, separating necessary and characteristic minutiae, and develops an MCMC-based algorithm for their inference.

Findings

The model effectively separates minutiae types in fingerprint data.

Characteristic minutiae contribute to fingerprint individuality.

The Bayesian approach provides accurate parameter estimation.

Abstract

Fingerprints feature a ridge pattern with moderately varying ridge frequency (RF), following an orientation field (OF), which usually features some singularities. Additionally at some points, called minutiae, ridge lines end or fork and this point pattern is usually used for fingerprint identification and authentication. Whenever the OF features divergent ridge lines (e.g. near singularities), a nearly constant RF necessitates the generation of more ridge lines, originating at minutiae. We call these the necessary minutiae. It turns out that fingerprints feature additional minutiae which occur at rather arbitrary locations. We call these the random minutiae or, since they may convey fingerprint individuality beyond the OF, the characteristic minutiae. In consequence, the minutiae point pattern is assumed to be a realization of the superposition of two stochastic point processes: a Strauss point process (whose activity function is given by the divergence field) with an additional hard core, and a homogeneous Poisson point process, modelling the necessary and the characteristic minutiae, respectively. We perform Bayesian inference using an MCMC-based minutiae separating algorithm (MiSeal). In simulations, it provides good mixing and good estimation of underlying parameters. In application to fingerprints, we can separate the two minutiae patterns and verify by example of two different prints with similar OF that characteristic minutiae convey fingerprint individuality.