NIST: Digital formats foil fingerprint matching

Standardized digital formats for fingerprint minutiae don't perform as well in matching fingerprints as do proprietary formats, according to the results of a large-scale test of interoperability and accuracy in biometric matching systems conducted by the National Institute of Standards and Technology.

Fingerprint minutiae are computerized descriptions of the characteristics of a fingerprint that indicate the position and orientation of ridges and other distinctive features. The test was initiated to evaluate the performance of recently developed standards for digitized fingerprint minutiae.

Some of the reduced accuracy in the standard minutiae templates can be compensated for by matching two fingerprints instead of one, but the most accurate formats were the proprietary formats, the Minutiae Exchange Interoperability Test discovered.

"Performance depended largely on how many fingerprints from an individual were being matched," NIST said in a press release. "Systems using two index fingers were accurate more than 98 percent of the time. For single, index-finger matching, the systems produced more accurate results with images than with standard minutia templates. However, systems using images and two fingers had the highest rates of accuracy, 99.8 percent."

Minutiae templates are an alternative to the use of images for fingerprint matching. As digital files, the templates are much smaller than fingerprint images, using less storage space and transmitting more quickly. However, vendors' techniques to convert images into minutiae templates are generally proprietary and the systems are not compatible.

The goal for less expensive, accurate and interoperable fingerprint matching systems for homeland security and other purposes has been driving a need for greater standardization among minutiae templates.

The institute tested whether the International Committee for Information Technology Standards' recent 378 fingerprint template standard is sufficiently accurate when applied by multiple vendors. Fifteen vendors took part in the tests: Biologica Sistemas Ltd.; Bioscrypt Inc.; Cogent Systems Inc.; Cross Match Technologies Inc.; Dermalog Identification Systems GMBH; Identix Inc.; Innovatrics; Motorola Inc.'s Biometrics Business Unit; NEC Corp.; Neurotechnologija Ltd.; NITGen Co. Ltd.; Sagem Morpho; Secugen Corp.; Spex Forensics; and Technoimagia Co., Ltd.

The agency tested both the minutiae A and B standards, with the enhanced B standard using supplementary information on fingerprint ridges. "The enhanced minutiae B template performed only marginally better than the basic minutiae A template," the NIST report stated.