© Jain, 2004 Fingerprint Matching TechniquesFingerprint Matching Techniques • Minutiae-based • Uses location, orientation, and minutia type • Point pattern matching problem • Hard decision is made on the correspondence • Correlation-based • Spatial correlation of template and query • Sensitive to rigid and non-linear transformation • Computationally expensive • Ridge Feature-based • Orientation and frequency of ridges, ridge shape, texture information, etc. are used • Suffers from low discriminative ability © Jain, 2004 Texture-based Fingerprint Representation Texture-based Fingerprint Representation (c) Fourier spectrum of (a)(a) Ridges in local region (b) Ridge directions in (a) The ridge pattern in a fingerprint may be viewed as an oriented texture pattern having a fixed dominant spatial frequency and orientation in a local neighborhood. The frequency is due to the inter-ridge spacing present in the fingerprint and the orientation is due to the ridge flow pattern © Jain, 2004 Filtered ImagesFiltered Images An input fingerprint image is filtered using 8 Gabor filters all having the same frequency but different orientations (0 o , 22.5 o , 45 o , 67.5 o , 90 o , 112.5 o , 135 o , 157.5 o ) © Jain, 2004 Texture-based RepresentationTexture-based Representation Compute variance of each cell (a) Filtered image (b) Square tessellation (c) Feature values © Jain, 2004 Ridge Feature MapRidge Feature Map The filtered images are examined using a square tessellation and the variance of pixel intensities in every cell is used as a feature value The ridge feature map is a fixed-length feature vector *Ross et al, “A Hybrid Fingerprint Matcher”, Pattern Recognition, Vol. 36, July 2003 © Jain, 2004 Performance of Hybrid Matcher (Minutiae & Texture) Performance of Hybrid Matcher (Minutiae & Texture) © Jain, 2004 Correlation-based Matching Algorithm • Normalized cross-correlation of regions around corresponding minutia points is used to describe the quality of a minutia match • Gray level values around the minutiae retain most of the local information; hence, this method determines the degree of minutia match accurately • Procrustes analysis of corresponding ridge curves is used to estimate rotations and displacements • Gabor filter-bank based technique is used for fingerprint enhancement and segmentation • Since correlation is done locally, the method is reasonably resistant to non-linear deformations © Jain, 2004 Fingerprint Matching using Local Correlation Correlation Minutia Extraction Estimation of Rotation and Translation using Ridge Correspondences Query MinutiaeQuery Image Template Image Template Minutiae Regions in Template around Template Minutiae Regions in Rotated Query Image around Transformed Template Minutiae Matching Score © Jain, 2004 Performance of Hybrid Matcher (Minutiae and Local Correlation) Performance of Hybrid Matcher (Minutiae and Local Correlation) MSU-VERIDICOM fingerprint database; 160 users and 4 impressions/user © Jain, 2004 Performance of Hybrid Matcher (Minutiae, Texture & Local Correlation) Performance of Hybrid Matcher (Minutiae, Texture & Local Correlation) © Jain, 2004 FVC 2004 ResultsFVC 2004 Results Algorithm EER(%) Avg Enroll Time (sec) Avg Match Time (sec) Avg Model Size (KB) Bioscrypt Inc. 2.07 0.08 1.48 2.07 0.67 0.71 1.19 24 Sonda Ltd 2.10 2.07 1.3 Chinese Academy of Sciences 2.30 0.35 16.4 Gevarius 2.45 0.69 2.0 Jan Lunter 2.90 1.01 3.1 • Database: – DB1: optical sensor "V300" by CrossMatch – DB2: optical sensor "U.are.U 4000" by Digital Persona – DB3: thermal sweeping sensor "FingerChip FCD4B14CB" by Atmel – DB4: synthetic fingerprints