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Fingerprint Recognition Through Circular Sampling. David Chang* and Joseph Hornak Rochester Institute of Technology Rochester, NY 14623-5604. Introduction. Useful for personal identification. Valuable to criminal investigators and forensic scientists. Overview. Introduction Background
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Fingerprint Recognition Through Circular Sampling David Chang* and Joseph Hornak Rochester Institute of Technology Rochester, NY 14623-5604
Introduction • Useful for personal identification. • Valuable to criminal investigators and forensic scientists.
Overview • Introduction • Background • Theory • Methods • Results • Conclusion • Future Work
Background • Fingerprint Uniqueness • Obstacles • AFIS Method
Fingerprint Uniqueness • Major: Central pattern • arch, loop, whorl
Fingerprint Uniqueness • Minor: Minutiae • ridge termination, bifurcation
Obstacles • Rotation • Displacement • Missing area • Image defects
AFIS Method • Image enhancement • Feature extraction • Feature mapping • Classification via flow maps • Matching • # of minutiae • Euclidean distances
Source Image Circle Sample Theory: Sampling Process
Theory: Sampling Process Fingerprint Image Concentric Circle Sample
Circular Correlation x Rotated x
A = 8 A = 16 MArea Ratio = 0.5 Match Metric: Area Ratio • Average of ratio between the areas of corresponding circles in the two samples being matched.
A = 8 A = 16 MAX = 6 MCorrelation Fraction = 0.75 Match Metric: Correlation Fraction • Average of the max value in the correlated signal divided by smaller area of corresponding circles in the two samples being matched.
Low Match Probability High Match Probability Match Metric: Angular Density • Determine mean square error (MSE) among angles corresponding to highest magnitude in the correlation signal. MAngular Density = 1 - 2(MSE)/
Methods • Source Images • 48 Synthetic Fingerprint Images • 512 x 512 pixels at 1-bit/pixel • Match Matrices • 48 x 48 matrix where each column sample is matched against each row source sample. • Done for the 3 metrics. • Observe effects • Missing Areas • Rotation • Examine displacement effects
Area Ratio Correlation Fraction Angular Density Results: Unchanged Variables
Fingerprint Image Quarter Area Removed Arbitrary Area Removed
Area Ratio Correlation Fraction Angular Density Results: Arbitrary Area Removed
Area Ratio Correlation Fraction Angular Density Results: Rotation Effects Column images rotated 45
MArea Ratio MCorrelation Fraction MAngular Density Arch 16 0 -16 16 0 -16 16 0 -16 -16 0 16 -16 0 16 -16 0 16 Loop 16 0 -16 16 0 -16 16 0 -16 -16 0 16 -16 0 16 -16 0 16 Whorl 16 0 -16 16 0 -16 16 0 -16 -16 0 16 -16 0 16 -16 0 16 Results: Displacement Effects
Conclusion • Of the three metrics, the angular density metric proves to be most effective. • Displacement effects show that a consistent selection of the circles center is necessary.
Future Work • Image enhancement • Test on actual fingerprints • Observe effects of less circles • Test on larger database • Code optimization
Fingerprint Chicks • Materials: • Yellow • Tempera paint • Wash tubs • Large construction paper • Glue • Directions: • 1.Each student chooses a construction paper for background. • 2.Have students come up one at a time, to gently dip their hands and fingers in the yellow tempera paint. • 3.Each will place their hands and fingers on their paper, making a fingerprint. • 4.Kids decorate their fingerprints to look like a new Spring chick.