NCJ Number
57718
Date Published
1976
Length
12 pages
Annotation
THE FINIDENT SYSTEM OF FINGERPRINT TRANSPARENCY CORRELATION, IN WHICH FINGERPRINT TRANSPARENCIES ARE PREPARED ELECTRO-OPTICALLY AS A LIBRARY FILE ON A FILMSTRIP OR IN A CYLINDRICAL HOLDER, IS DISCUSSED.
Abstract
IN THE FINIDENT SYSTEM, FINGERPRINT TRANSPARENCIES ARE PROCESSED TO OBTAIN THEIR CORRELATION MEASURE. THE FOURIER TRANSFORM OF THE LIBRARY AND SAMPLE TRANSPARENCIES PLACED SIDE-BY-SIDE IS ACCOMPLISHED BY COHERENT OPTICAL MEANS. THE FOURIER TRANSFORM IS DETECTED BY MEANS OF A SQUARE-LAW PHOTO-DETECTOR ARRAY AND ITS POWER SPECTRUM ANALYZED ELECTRONICALLY. THE SPECTRAL ANALYSIS OF THE POWER SPECTRUM IS RELATED TO THE CROSS CORRELATION FUNCTION OF THE TWO TRANSPARENCIES. PRELIMINARY TESTS OF THE SYSTEM WERE PERFORMED WITH TWO MATRIXES OF FINGERPRINT TRANSPARENCY RECORDS. FOR A 15 BY 15 MATRIX (225 COMPARISONS) OF ROLLED FINGERPRINT SAMPLES COMPARED WITH THE SAME FINGERPRINTS PREPARED AS A LIBRARY FILE, THE SYSTEM PERFORMED AS EXPECTED AND WITHOUT ERRORS. TWO ERRORS WERE MADE FOR A 12 BY 12 MATRIX (144 COMPARISONS) WHEN THE ROLLED FINGERPRINT LIBRARY WAS COMPARED WITH PRESSED (PLAIN) FINGERPRINT SAMPLES. AN ERROR IS DEFINED AS A NONCORRESPONDING LIBRARY TRANSPARENCY BEING MORE SIMILAR TO THE SAMPLE THAN ITS CORRESPONDING LIBRARY TRANSPARENCY. THE ERRORS MAY BE DUE TO DIFFERENCES IN DISTORTIONS INTRODUCED BY THE DIFFERENT IMPRESSION METHODS, INKING DIFFERENCES, IMPROPER CORRESPONDENCES OF PATTERN AREAS COMPARED, OR SOME COMBINATION OF THE ABOVE FACTORS. FURTHER STUDY IS REQUIRED TO DETERMINE THE SOURCE OF THE ERRORS. FIGURES, TABLES, AND REFERENCES ARE PROVIDED. APPENDIXES EXAMINE THE BASIC THEORY OF THE FINIDENT SYSTEM AND THE ELECTRONICS INVOLVED. SEE ALSO NCJ 38864, 52569, 5770757717, AND 57719-57726. (AUTHOR ABSTRACT MODIFIED--PRG)