Fingerprint recognition and retrieval system

• US 4,817,183 A
• Filed: 04/01/1987
• Issued: 03/28/1989
• Est. Priority Date: 06/16/1986
• Status: Expired due to Fees

• Current Assignee: Malcolm K. Sparrow
• Original Assignee: Malcolm K. Sparrow
• Inventors: Sparrow, Malcolm K.
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Mancuso, Joseph
• Application Number:
  US07/032,806
• Time in Patent Office: 727 Days
• Field of Search: 382/4, 382/5, 382/34, 382/26, 382/19, 356/71
• US Class Current: 382/125
• CPC Class Codes: G06V 40/1347 Preprocessing; Feature extraction
• CPC Class Codes: G06V 40/1365 Matching; Classification
• CPC Class Codes: G07C 9/37 using biometric data, e.g. fingerprints, iris scans or voice recognition

Abstract

Fingerprints are scanned by a scanning system (13). Topological systems for coding and comparing fingerprints are described including a system for recording a description of fingerprints. In a preferred embodiment, a central point of the fingerprint is selected as a center of rotating scan line. The scan line is rotated to different topological characteristics. A code (T) representing the type of irregularity is recorded (16, 17). A measure (M) of the scanning position when encountering the irregularity is made (16, 17). In the case of a rotating scan line the angular cordinate (θ) is recorded. The ridge count (R) (16) is also recorded. A list of coordinate sets (T, θ, R) specifies the topology of a sector. For fragmentary prints similar coordinate sets are generated. A fourth coordinate can be added corresponding to the radial distance (D) (16). A full set of coordinates (T, θ, R, D) gives a complete topological and spatial description of a fingerprint. Comparison of fingerprints can then be conducted by a computer (20).

Claims

1. A fingerprint recognition and retrieval method comprising,

I. establishing a machine searchable library of fingerprints by, for each file fingerprint,

(a) locating a central reference point and projecting a line in a predetermined direction through the said central point to intersect ridge lines to each side of said centrally located reference point,

(b) from the point of crossing of said projected line with each ridge, and in a predetermined order, tracing each side of said ridge crossings from said projected line to the first occurring topological event and assigning a type code (T) to the event, and measuring the distance (D) from the projected line crossing to the event, and

(c) recording each type code (T) and distance (D) in said predetermined order as a topological data vector for each file fingerprint in a machine searchable database,

II. with respect to unknown latent or rolled fingerprints, locating a central reference point on said unknown latent or rolled fingerprint and projecting a line through the said central point to intersect ridge lines to each side of said centrally located reference point,

from the point of crossing of said projected line with each ridge, and in a predetermined order, tracing each side of said ridge crossings from said projected line to the first occurring topological event and assigning a type code (T_u) to the event, and measuring the distance (D_u) from the projected line crossing to the event,

forming a code vector comprised of said type codes and said distances, and

III. comparing said code vector with such code vectors machine searchable library of file fingerprints in order to identify which file fingerprint in the said file collection corresponds to the said unknown fingerprint, with respect to measured distances D and D_u at apparently matching events, and in addition to comparing the absolute distances D and D_u, performing at least one further comparison of said measured distances selected from (1) a predetermined differential distance tolerance between events on adjacent ridges on the same side of said projected line, respectively, and (2) predetermined summed distance tolerance of the pairs of ridge events to each side of said ridge crossings, respectively.

2. A system for searching an unknown latent or rolled fingerprint against a rolled fingerprint database comprised of a machine searchable library of rolled fingerprints coded in the topological data vector format, comprising:

I. means for establishing a machine searchable library of file fingerprints comprising the steps of, for each file fingerprint,

means for locating a central reference point and projecting a line in a predetermined direction through the said central reference point to intersect ridge lines to each side of said central reference point,

means for tracing, in a predetermined order, each side of said ridge crossings from said projected line to the first occurring topological event and assigning a type code (T) to the event,

measuring means for measuring the distance (D) from the projected line crossing to the event, and

recording means for recording each type code (T) and distance (D) in said predetermined order as a topological data vector in a machine searchable database,

II. means for locating a central reference point on said unknown fingerprint and projecting a line through the said central point to intersect ridge lines to each side of said centrally located reference point,

tracing means for tracing, in a predetermined order, each side of said ridge crossings from said projected line to the first occurring topological event and assigning a type code (T_u) from the projected line crossing to the event,

coding means for forming a code vector comprised of said type codes and said distances, and

III. comparator means for comparing said code vector with such code vectors recorded in the database in order to identify which known fingerprint in the said file collection corresponds to the said unknown fingerprint, including,

comparing said code vector with such topological data vectors in said machine searchable library of file fingerprints in order to identify which file fingerprint in the said file collection corresponds to the said unknown fingerprint, and with respect to measured distances D and D_u at apparently matching events, in addition to comparing the absolute distances D and D_u, performing at least one further comparison of said measured distances selected from (1) differential distance tolerance between events on adjacent ridges on the same side of said projected line, respectively, and (2) summed distance tolerance for two events on a common ridge and to each side of said ridge crossings, respectively.