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

ANSI/NIST-ITL 1-2011Data Format for the Interchange of Biometric and Forensic InformationFigure 21:EFS Locations of major flexion creases13.9.43 EFS Field 9.342 Creases and Linear Discontinuities / CLDRidge edge features include Protrusions (abrupt increases in ridge width),Indentations (abrupt decreases in ridge width), and Discontinuities (points wherea ridge stops briefly):A protrusion (or spur) is an abrupt increase in ridge width that is not longenough to be called a bifurcation. An event on a ridge longer than local ridgewidth shall be marked as a standard bifurcation with a ridge ending; a shorterevent shall be marked as a protrusion. Protrusions are marked at the centerof the protruding area.An indentation is an abrupt decrease in ridge width. Indentations are markedat the center of the gap in the ridge.A discontinuity is a point where the ridge stops briefly and restarts againwithout shifting. A wider gap in the ridge flow, or where the ridges do not lineup across the divide, should be marked as two ridge endings, not adiscontinuity. A series of discontinuities in a line (such as a cut or crack)Brad Wing 6/23/10 1:09 PMComment: Reorganized for consistencyofpresentation106DRAFT 2