Pattern recognition apparatus

• US 4,015,240 A
• Filed: 02/12/1975
• Issued: 03/29/1977
• Est. Priority Date: 04/09/1973
• Status: Expired due to Term

• Current Assignee: Secure Technologies Group, Inc.
• Original Assignee: Calpine Corporation
• Inventors: Swonger, Claron W., Stock, Robert M., Ryan, Hollis F., Vossler, Charles M.
• Primary Examiner(s): Boudreau, Leo H.
• Application Number:
  US05/549,399
• Time in Patent Office: 776 Days
• Field of Search: 340/146.3 E, 340/146.3 MH, 340/146.3 H, 340/146.3 AG, 340/146.3 AC
• US Class Current: 382/125
• CPC Class Codes: A61B 5/1172 using fingerprinting
• CPC Class Codes: G06V 40/1347 Preprocessing; Feature extraction
• CPC Class Codes: G07C 9/37 using biometric data, e.g. fingerprints, iris scans or voice recognition

Abstract

A pattern recognition apparatus for recognizing or identifying fingerprint images and the like is described. The apparatus enables the determination of the coordinates and angular positions of characteritic points such as fingerprint minutiae. The pattern recognition apparatus includes a high resolution scanner for scanning a fingerprint impression or image, an analog to digital converter to convert the scanner signals to a digitally encoded image having many levels of gray scale data, an image enhancer to eliminate imperfections in the imagery, pre-editing circuits to edit out areas of the image which should not be further processed, a minutiae detection system having high redundancy to reduce the probability of missed minutiae, and a post-editing subsystem to eliminate false minutiae detections.

Claims

1. Pattern recognition apparatus enabling the determination of the coordinates and angular positions of characteristic points such as fingerprint minutiae, comprising;

a. sensing means developing a plurality of signals in response to a presented pattern containing characteristic points which are to be identified,

b. conversion means responsive to said signals for converting said pattern into a binary encoded image containing many levels of gray scale data,

c. temporary storage means for temporarily storing in a predetermined sequence portions of said data, which portions comprise sets of points corresponding to said binary encoded image, each point of which having a value indicative of the gray scale level thereof,

d. means for comparing and averaging said data in said storage means for converting said data into a second binary encoded image comprised of sets of points, each containing one of two levels of gray scale data and which image has been corrected for imperfections in said presented pattern, said means comprise a plurality of logic circuits all of which simultaneously compare and average portions of said data,

e. continuity means for detecting only those points of said second binary encoded image that are contiguous to a predetermined set of coordinates in said presented pattern, said means comprise a plurality of continuity logic circuits all of which simultaneously detect contiguous points located in portions of said second binary encoded image whereby the detection of all points therein is simultaneous,

f. means for detecting and determining values indicative of various geometric properties of said contiguous points including the coordinates and angular positions thereof and comparing the same with a plurality of predetermined threshold values, and

g. characteristic point storage means for receiving the coordinate and angular positions of said contiguous points which fall within said threshold values.

7. The apparatus according to claim 1, wherein each of said continuity logic circuits detect the value of four central points in said second binary encoded image and detect the value of an additional point therein and is responsive to the output of others of said continuity logic circuits each of which detects as one of its four central points a point contiguous to said additional point for detecting the value of said contiguous point.

3. The apparatus according to claim 3, wherein each of said comparing and averaging logic circuits comprise;

means for comparing the average value of a set of points of said first mentioned binary encoded image, said set containing as one of its points a central point in said temporary storage means, with the average of all of said sets of points in said temporary storage means whereby said central point is converted to a point in said second binary encoded image as a function of said average of said set and the average of all of said sets.

2. The apparatus according to claim 3, further comprising:

h. means responsive to said characteristic point storage means for determining which of said contiguous points have substantially the same coordinates and angular positions.

4. The apparatus according to claim 5, wherein said sets of points in said temporary storage means to which all of said logic circuits are responsive are arranged in radial spoke-like fashion through said central point.

5. The apparatus according to claim 3, wherein each of said continuity logic circuits detect the value of four central points in said second binary encoded image and detect the value of an additional point therein and is responsive to the output of others of said continuity logic circuits each of which detects as one of its four central points a point contiguous to said additional point for detecting the value of said contiguous point.

6. The apparatus according to claim 3, wherein each of said continuity logic circuits detect the value of four central points in said second binary encoded image and detect the value of an additional point therein and is responsive to the output of others of said continuity logic circuits each of which detects as one of its four central points a point contiguous to said additional point for detecting the value of said contiguous point.