NCJ Number
61031
Date Published
1978
Length
9 pages
Annotation
THE COMPUTER TECHNICAL FINGERPRINT-SEARCH SYSTEM, USED BY THE ARIZONA DEPARTMENT OF PUBLIC SAFETY, AND BASED ON THE CONCEPT OF RIDGE ANGLE SAMPLING AS A WAY OF AUTOMATICALLY PROCESSING FINGERPRINTS IS REPORTED.
Abstract
THE IDENTIFICATION METHOD USED IN THE SYSTEM IS CONCERNED WITH MEASURING TOPOGRAPHICAL FEATURES OF FINGERPRINTS. FINGERPRINT RIDGE INFORMATION IS OBTAINED BY SAMPLING THE RIDGE DIRECTION OVER A SQUARE ARRAY OF 840 LOCATIONS CENTERED OVER THE FINGERPRINT BOX OF A STANDARD FINGERPRINT CARD. EACH OF THE 840 RIDGE ANGLES IS REPRESENTED AS AN 8-BIT INTEGER NUMBER SO THAT RAW FINGERPRINT DATA EXTRACTED FROM A CARD ARE CONTAINED IN A 4,200-WORD RECORD. A COHERENT OPTICAL SCANNER IS EMPLOYED TO SCAN 35-MM NEGATIVES OF FINGERPRINT CARDS AND GENERATE RIDGE ANGLE DATA. COMPUTER PROCESSING IS THEN APPLIED TO DETERMINE FINGERPRINT CLASSIFICATIONS AND CHARACTERISTIC MEASURES OF FINGERPRINT PATTERNS. A 120-WORD IDENTIFICATION RECORD IS PRODUCED AFTER COMPUTER PROCESSING. THIS RECORD IS STORED ON A MAGNETIC DISK TO FORM THE COMPUTER FINGERPRINT FILE OR IS USED TO SEARCH THE FILE. EVALUATION TESTS INDICATE THAT THE COMPUTER TECHNICAL SEARCH SYSTEM ACHIEVES A SUBSTANTIALLY HIGHER HIT RATE THAN THE RATE ACHIEVED BY MANUAL PROCEDURES AND THAT THE SMALL QUANTITY OF DATA ABSTRACTED FROM FINGERPRINT CARDS ENABLES RAPID DIGITIZATION, PROCESSING, AND SEARCH WITH FLEXIBLE COMPUTER SOFTWARE TECHNIQUES. ILLUSTRATIONS, PHOTOGRAPHS, AND REFERENCES ARE PROVIDED. (DEP)