acknowledgements for ansi/nist-itl 1-2011 - NIST Visual Image ...

ANSI/NIST-ITL 1-2011 - UPDATE 2013 DRAFT VERSIONFigure 42: Examples of fingerprint, skeletonized representation, and overlay of original /skeleton / quality mapA ridge skeleton can represent sophisticated interrelationships between features. For example,Figure 41 shows that the bifurcation in green shares the same ridge with the three minutiae inred. The human latent fingerprint comparison process relies heavily on such featureinterrelationships.Note that the PATH format permits the treatment of each ridge segment as a distinct feature,indexed by its (1-based) subfield number. Each ridge segment can be associated with theminutiae at its ends and features such as pores and ridge edge features along its length. Dots andincipients can be associated with the ridge segments on either side. Each ridge ending isassociated with one ridge segment; each bifurcation is associated with three ridge segments.In the case that the type of minutia cannot be determined or its precise location cannot beascertained, a minutia can be tentatively associated with any ridge segments that cross theminutia’s radius of uncertainty, as shown in Figure 43.Figure 43: Examples of minutiae of uncertain type and radii of uncertainty, without andwith ridge segmentsF.6.8.1 Field 9.372: EFS skeletonized image / SIM instructionsThe skeletonized image, also known as a ridge tracing, is stored as a 1-bit per pixel grayscalePNG 203 compressed image, bit-packed 6 bits per character using base-64 representation (SeeAnnex A: Character encoding information). (Note that the result is a bit-packed image with6 pixels per base-64 character.) The entire PNG-formatted image file is included as a singlesubfield. Interlacing, alpha transparency, and color palettes shall not be used. The resolution of203See ISO/IEC 15948:2004 in Section 3 Normative references.May, 2013 DRAFT VERSION UPDATE 2013 Page 505