Fingerprint processing system capable of detecting a core of a fingerprint ...

United States Patent [19]

Hara

[ii] Patent Number: 5,040,224 [45] Date of Patent: Aug. 13, 1991

[54] FINGERPRINT PROCESSING SYSTEM CAPABLE OF DETECTING A CORE OF A FINGERPRINT IMAGE BY STATISTICALLY PROCESSING PARAMETERS

[75] Inventor: Masanori Hara, Tokyo, Japan

[73] Assignee: NEC Corporation, Tokyo, Japan

[21] Appl. No.: 342,047

[22] Filed: Apr. 24, 1989

[30] Foreign Application Priority Data

Apr. 23, 1988 [JP] Japan 63-99334

Apr. 23, 1988 [JP] Japan 63-99335

Apr. 23, 1988 [JP] Japan 63-99336

[51] Int. CI.5 G06K 9/00

[52] U.S. a 382/4; 382/5

[58] Field of Search 382/4, 5, 39

[56] References Cited

U.S. PATENT DOCUMENTS

4,151,512 4/1979 Piganati et al 382/5

4,185,270 1/1980 Fischer et al 382/5

4,310,827 1/1982 Asai 382/5

4,747,147 5/1988 Sparrow 382/5

FOREIGN PATENT DOCUMENTS

58- 55549 12/1983 Japan .

59- 27945 7/1984 Japan .

Primary Examiner—David K. Moore

Assistant Examiner—Jose L. Couso

Attorney, Agent, or Firm—Sughrue, Mion, Zinn,

Macpeak & Seas

[57] ABSTRACT

In a fingerprint processing system for use in detecting a core position of a fingerprint image quantized into a plurality of picture elements, statistical processing is carried out in relation to parameters which are variable in dependency upon the core position and directions and curvatures of the picture elements preliminarily detected to specify ridges of the fingerprint image. The parameters may be existence probabilities of the core position that are determined for the directions and the curvatures. Such existence probabilities are successively calculated at each picture element and adjacent picture" elements to be summed up and to detect a maximum one of the existence probabilities. A position which has the maximum existence probability is judged as the core position. Alternatively, the parameters may be differences between practical curvatures extracted from the fingerprint image and reference curvatures defining a reference curve. A minimum one of the differences is statistically detected with reference to various kinds of the reference curves. In addition, the directions and the curvatures of the picture elements may be determined by deriving the density levels of the picture elements along a plurality of arcuate lines specified by line directions and line curvatures.

2 Claims, 11 Drawing Sheets