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

ANSI/NIST-ITL 1-2011Data Format for the Interchange of Biometric and Forensic Informationrepresentation. The entire PNG-formatted image is included as a single dataentry. Interlacing, alpha transparency, and color palettes shall not be used. Theresolution of the skeletonized image must be the same as the original image.Each black pixel can have 1,2, or 3 neighboring black pixels (1,2,3-connexity);other values (0, 4-8) are errors. The skeletonized image’s dimensions shall beidentical to the Region of Interest (ROI).The values in Field 9.308 Ridge Quality/Confidence Map / RQM are used todistinguish between the areas in which the skeleton is debatable and those inwhich it is definitive.Table 45 shows the relationship between the local quality values and the tracing.Table 45:EFS codes for local ridge quality and tracingRidge path Local Quality Code NameRidge path isdefinitiveRidge path isdebatableNo ridge path5 Definitive pores4 Definitive ridge edges, debatable pores3 Definitive minutiae, debatable ridge edges2 Definitive ridge flow, debatable minutiae1 Debatable ridge flow0 Background13.9.63 EFS Field 9.373 Ridge Path Segments / RPSRidge path representation is a means of annotating the image (rather thanreplacing the image). It is a clear way of defining and communicating the specificpath of each ridge, both for a human examiner and an automated extractor. Theridge path can be decomposed of a number of ridge path segments. Each ridgepath segment (if completely visible) is the portion of a ridge that connects twominutiae, so each ridge path segment starts and stops either where the ridgeintersects another ridge path segment (a bifurcation) or ends (a ridge ending). Inthe infrequent case in which a ridge segment forms a complete loop back onitself without intersecting another ridge segment (such as near the core of someplain whorls or central pocket loops), the ridge path starts and stops at a singlearbitrary point on the ridge.125DRAFT 2