Method for extracting high-level features for fingerprint recognition

United States Patent [w]

Hsiao et al.

[54] METHOD FOR EXTRACTING HIGH-LEVEL FEATURES FOR FINGERPRINT RECOGNITION

[75] Inventors: Pei-Yung Hsiao, Taipei; Shu-Fang Hsu, Chu-Nan, both of Taiwan

[73] Assignee: Aetex Biometric Corporation, Taipei, Taiwan

[21] Appl. No.: 08/788,995 [22] Filed: Jan. 27, 1997

[51] Int. CI.6 G06K 9/00

[52] U.S. CI 382/125; 382/205; 382/279

[58] Field of Search 382/124, 125,

382/126, 127, 205, 279; 356/71; 396/101

[56] References Cited

U.S. PATENT DOCUMENTS

3.419,287 12/1968 Rudie 356/71

4^607,384 8/1986 Brooks 382/124

4^724,544 2/1988 Matsumoto 382/205

4,933,976 6/1990 Fishbine et al 382/127

5,040,224 8/1991 Hara 382/124

5,128,706 7/1992 Shindo et al 396/101

5440,642 8/1992 Hsu et al 382/124

5^233,670 8/1993 Dufour et al 382/205

5,438,636 8/1995 Surka 382/279

5,497,429 3/1996 Shibuya 382/125

5,572,597 11/1996 Chang et al 382/125

5,659,626 8/1997 Ort et al 382/125

Primary Examiner—-Joseph Mancuso
Assistant Examiner—Gilberto Frederick, II

[57] ABSTRACT

A method to extract automatic high level features of a gray level ridge flow image including the automatic determination of the location of the high level features including the core and delta points of a fingerprint image in the form of a gray level image, comprising the following five steps:

(1) determining a ridge flow direction of each gray level pixel of a fingerprint image and assign it with a direction code;

(2) finding out a block directional flow and assigning each with appropriate direction code thereof;

(3) correcting block flow directions in which a detection of the flow direction is affected image an input image quality in order to be immune from noises infiltrated during the acquiring process;

(4) locating the delta points which are based on a corrected block direction flow diagram to locate from zero to a few delta points; and

(5) locating the core points which are based on a corrected block direction flow diagram to locate one to two core points.

5 Claims, 11 Drawing Sheets