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

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

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<strong>ANSI</strong>/<strong>NIST</strong>-<strong>ITL</strong> 1-<strong>2011</strong>Data Format for the Interchange of Biometric and Forensic Information13.7.24 EFS Field 9.320 Cores / CORA core is located at the focus of the innermost recurving ridgeline of a ridgepattern: if the ridge is viewed as a section of a circle, the core is the center of thatcircle; if the ridge is viewed as an ellipse or parabola, the core is the focal point ofthat curve. The direction of the core is away from the center of the curve. Figure12 shows an example of how the core is placed. Note that the core is not on theinnermost recurving ridgeline itself.Figure 12:Placement of the core at the focus of the innermost recurvingridgelineThe core or cores of a fingerprint are defined for all pattern classifications otherthan plain arches, as shown in Table 26.Cores may be marked on tented arches if an innermost recurving ridge ispresent above the delta, so that each side of the recurving ridge extends toeither side of the delta.Plain or central pocket loop whorls will only have one core if the innermostrecurving ridge is circular, or two cores if elliptical. A circular whorl only hasone core and does not have a defined direction.Accidentals may have any number of cores.For palmprints or other non-fingerprint friction ridge images, any number of corelikepatterns may be defined using this field if such structures are present.Table 26: Number of cores and deltas by pattern classPattern Classification Cores DeltasArchesWhorls- Plain Arch 0 0- Tented Arch 0 or 1 0 or 1- Plain Whorl 1 or 2 2- Central Pocket Loop 1 or 2 285DRAFT 2

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