公开(公告)号：US3560928A

公开(公告)日：1971-02-02

申请号：US3560928D

申请日：1968-09-25

Applicant: IBM

Inventor： BERGER JAY M ,  LEVINE WILBUR J ,  MALEK KASEM

IPC: G06K9/00 ,  G06K9/16

CPC classification number: G06K9/00067

Abstract: A DOCUMENT HAVING A PATTERN TO BE RECOGNIZED, SUCH AS A FINGERPRINT, IS FIRST SCANNED AT A FIRST ANGLE IN ONE DIRECTION TO DETERMINE A FIRST SET OF POINTS OF TANGENCY OF SCANNING LINES WITH FINGERPRINT RIDGES AND THE ADDRESSES OF THE X, Y COORDINATES OF THESE POINTS ARE STORED IN DIGITAL STORAGE MEANS. THE SCAN IS THEN ROTATED TO AN ANGLE OF ABOUT 60* TO 120* TO THE FIRST ANGLE AND A SECOND SCAN IS EFFECTED TO PRODUCE A SECOND SET OF LIKE POINTS OF TANGENCY AND THE ADDRESSES OF THE X, Y COORDINATES OF THE SECOND POINTS ARE ALSO STORED. THE ADDRESSES PRODUCED BY BOTH SCANS ARE RESPECTIVELY COMPARED AND THAT COMPARISON BETWEEN FIRST AND SECOND SCAN ADDRESSES WHICH SHOWS A DIFFERENCE OF LESS THAN A CHOSEN VALUE (THE DISTANCE BETWEEN ADJACENT RIDGES OF THE FINGERPRINT) IS THE LOCATION AT WHICH THE SCANS CONVERGE AND WHICH IS SUBSTANTIALLY THE FOCAL POINT OF THE FINGERPRINT. SUCH FOCAL POINT IS NOW REPRODUCIBLE, NO MATTER WHAT THE ANGLE OF DISPOSITION OF THE FINGERPRING IS IN THE VIEWING AREA.