AVR (ANALOGUE VIDEO RESHAPING SYSTEM) - A NEW APPROACH TO SOME PROBLEMS OF FINGERPRINT COMPARISON

• NCJ Number: 54402
• Journal: Police Journal Volume: 52 Issue: 1 Dated: (JANUARY-MARCH 1979) Pages: 57-65
• Author(s): R M APPLEBY
• Date Published: 1979
• Length: 4 pages
• Corporate Author: Justice of the Peace, Ltd
• Publication Format: Article
• Language: English
• Country: United Kingdom

Annotation

THE ANALOGUE VIDEO RESHAPING (AVR) SYSTEM, USED BY THE NEW SCOTLAND YARD (ENGLAND) TO COMPARE BIOLOGICAL AND GEOLOGICAL MATERIAL AND TO REMOVE DISTORTION FROM CRUSHED OR DISTORTED FINGERPRINTS, IS DESCRIBED.

Abstract

THE AVR SYSTEM FOR FINGERPRINT COMPARISON CONSISTS OF TWO TELEVISION CAMERAS, IMAGES FROM WHICH ARE DISPLAYED TOGETHER ON ONE TELEVISION MONITOR VIA A MULTIPLEXING DEVICE THAT RAPIDLY SWITCHES SIGNALS ULTIMATELY DERIVED FROM THE TWO CAMERAS. THE PICTURE OUTPUT FROM THE FIRST CAMERA IS NOT MODIFIED AS IT IS PASSED THROUGH THE MULTIPLEXER TO THE OPERATOR'S MONITOR, EXCEPT FOR THE OPTIONAL USE OF A VIDEO INVERTER THAT ALLOWS THE CHOICE OF A POSITIVE OR NEGATIVE PICTURE. THE SECOND CAMERA FEEDS A SYNC SEPARATOR. VIDEO INFORMATION IS PROCESSED SIMILARLY TO THAT FROM THE FIRST CAMERA, BUT CERTAIN SYNC PULSES ARE USED TO DRIVE SPECIAL TIMEBASES AND THEIR MODIFIERS. MODIFIERS ARE MODULES IN WHICH BOTH TIMEBASES ARE ALTERED BY SUITABLY SYNCHRONIZED FUNCTION GENERATORS SO THAT LINEARITY, AMPLITUDE, AND SHIFTS ARE WIDELY VARIABLE. IT IS THUS POSSIBLE TO SCALE, DISTORT, SQUEEZE, AND STRETCH TIMEBASES GENERATED FROM THE SECOND CAMERA SO THAT AN ORIGINALLY DISTORTED FINGERPRINT MAY BE MATCHED TO AND SUPERIMPOSED UPON AN UNDISTORTED PRINT VIEWED BY THE FIRST CAMERA. USING THE SAME PROCESS, FRAGMENTARY PRINTS MADE IN DIFFERENT WAYS HAVE BEEN SUCCESSFULLY JOINED TO MAKE A MORE COMPLETE PRINT. THE SCALING FACILITY ENABLES IMAGES OF DIFFERENT SIZES TO BE EMPLOYED WHILE BRILLIANCE SETTINGS PERMIT THE EFFECTIVE DEMONSTRATION OF A MATCH. WHERE ONLY DISTORTED SCENE-OF-CRIME FINGERPRINTS ARE AVAILABLE, AVR STUDIES INDICATE THE POSSIBILITY OF MODIFYING PRINTS TO A STANDARD FORMAT USING DIGITAL STORAGE SO THAT A STORE OF COMPATIBLE PRINTS MAY BE ACCUMULATED, THUS FACILITATING COMPARISON AND IDENTIFICATION AT A LATER DATE. FINGERPRINT PHOTOGRAPHS, A BLOCK DIAGRAM OF THE AVR, AND REFERENCES ARE INCLUDED. (DEP)