ADAPTIVE DIGITAL ENHANCEMENT OF LATENT FINGERPRINTS (FROM CARNAHAN CONFERENCE ON CRIME COUNTERMEASURES PROCEEDINGS, 1978, BY JOHN S JACKSON - SEE NCJ-61021)

• NCJ Number: 61032
• Author(s): R P CHIRALO; L L BERDAN
• Date Published: 1978
• Length: 5 pages
• Corporate Author: Ores Publications
• Publication Format: Document
• Publication Type: Statistics
• Language: English
• Country: United States of America

Annotation

THIS ADAPTIVE TECHNIQUE FOR ENHANCING LATENT FINGERPRINTS INVOLVES BINARIZATION AND RESOLUTION AND SAMPLING CONSIDERATIONS IN THE PREPROCESSING OF FINGERPRINTS BEFORE ENCHANCEMENT.

Abstract

THE ADAPTIVE BINARIZATION TECHNIQUE EXPLOITS THE FACT THAT, OVER ANY GIVEN REGION OF A FINGERPRINT, GREY TONES OF RIDGES ARE DARKER THAN AVERAGE GREY TONES WHILE VALLEYS ARE LIGHTER THAN THE AVERAGE. BY SELECTING A SUITABLE REGION SIZE, COMPUTING THE REGION AVERAGE, AND SETTING RIDGES AND VALLEYS TO DISTINCT AND CONSTANT GREY LEVELS, VARYING GREY TONES OF LATENT FINGERPRINTS RESULTING FROM UNEVEN IMPRESSIONS CAN BE REMOVED WITH CONSIDERABLE SUCCESS. ADAPTIVE BINARIZATION REQUIRES THAT FINGERPRINTS BE CONVERTED FROM PHOTOGRAPHIC TO DIGITAL FORM. A PHOTOGRAPHIC NEGATIVE OF A LATENT FINGERPRINT IS RASTER-SCANNED ON A MICRODENSITOMETER. AN ANALOG-TO-DIGITAL CONVERSION OF THE DETECTED DENSITY SIGNAL TRANSFORMS THE FINGERPRINT IMAGE FROM A TWO-DIMENSIONAL ANALOG DENSITY FUNCTION TO A TWO-DIMENSIONAL DIGITAL FUNCTION THAT CAN ASSUME INTEGER VALUES RANGING FROM 0 TO 1,023. APPLICATIONS OF THE ADAPTIVE BINARIZATION TECHNIQUE TO ENCHANCE LATENT FINGERPRINTS ARE CITED. EQUATIONS, SAMPLE FINGERPRINTS, FOOTNOTES, AND REFERENCES ARE INCLUDED. (DEP)