ANSI/NIST-ITL 1-2011 - NIST Visual Image Processing Group ...

ANSI/NIST-ITL 1-2011Data Format for the Interchange of Biometric and Forensic InformationA ridge skeleton can represent sophisticated interrelationships between features.For example, Figure 24 shows that the bifurcation in red shares the same ridgewith the three minutiae in green. The human latent fingerprint comparisonprocess relies heavily on such feature interrelationships.Note that the PATH format permits the treatment of each ridge segment as adistinct feature, indexed by its data entry (occurrence) number. Each ridgesegment can be associated with the minutiae at its ends and features such aspores and ridge edge features along its length. Dots and incipients can beassociated with the ridge segments on either side. Each ridge ending isassociated with one ridge segment; each bifurcation is associated with threeridge segments.In the case that the type of minutia cannot be determined or its precise locationcannot be ascertained, a minutia can be tentatively associated with any ridgesegments that cross the minutia’s radius of uncertainty, as shown in Figure 26.Figure 26: Examples of minutiae of uncertain type and radii ofuncertainty, without and with ridge segmentsEach ridge path segment is saved as an open path (ordered set of vertices).Incipient ridges, dots, ridge discontinuities, and protrusions are not included inthe ridge path representation. Each skeletized ridge segment is stored as aseparate data entry (occurrence). Each endpoint of a ridge segment is eithershared by 3 ridge segments (at a bifurcation) or is unique to a single ridgesegment (at a ridge ending).127DRAFT 2