Method and apparatus for detecting forged signatures

• US 5,909,500 A
• Filed: 03/24/1998
• Issued: 06/01/1999
• Est. Priority Date: 01/02/1996
• Status: Expired due to Fees

• Current Assignee: Steven Jerome Moore
• Original Assignee: Steven Jerome Moore
• Inventors: Moore, Steven Jerome
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Werner, Brian P.
• Application Number:
  US09/046,820
• Time in Patent Office: 434 Days
• Field of Search: 382/119, 382/123, 382/137, 382/186, 382/203, 382/204, 382/174, 382/182, 382/187, 382/101, 382/179, 382/116, 382/177, 382/189, 382/193, 382/199, 382/200, 348/161, 283/57, 283/58, D19/11, 235/3, 434/155
• US Class Current: 382/123
• CPC Class Codes: G06V 40/30 Writer recognition; Reading and verifying signatures
• CPC Class Codes: G07C 9/35 by means of a handwritten signature

Abstract

The present invention provides a method for reducing the variations attendant to free-form execution of a signature by providing a delimiting area in which a signature string, and/or portions of a signature string, is/are to be constrainedly transcribed. Also disclosed is a method of signature verification based on analysis of the environs attendant to the signature-string. Such method comprises analyzing the delimited areas attendant to one or more exemplar signatures; determining highly correlative relationships between two or more delimited areas within the signature strings of the exemplar library thereby identifying archetypical delimited areas; causing an unauthenticated signature to be signed in a delimiting manner corresponding to the manner in which the exemplar signatures were delimitedly signed; searching for delimited areas in the unauthenticated signature corresponding to the archetypical delimited areas; determining whether such corresponding archetypical delimited areas of the unauthenticated signature display the same inter-relationships as the archetypical delimited areas with respect to the exemplar signatures; and rejecting as non-authenticate unauthenticated signatures having little correspondence to the exemplar signatures with respect to such highly correlative delimited areas and the relationship there-between.

Claims

1. A method for improving with respect to an individual, signature string uniformity within a plurality of signature strings, and for reducing variations attendant to execution of a signature string, for use of such signature strings in automated signature verification systems comprising:

a) delimiting the area in which said signature string is to be placed;

b) delimiting within said delimited signature string area the areas in which two or more characters, but less than all the characters, comprising the signature string are to be constrainedly written, thereby forming delimited character areas;

c) instructing an individual to place said signature string in said delimited signature string area and said two or more characters of said signature string in said delimited character areas of said delimited signature string area; and

d) comparing by automated means the resulting constrained signature against one or more authenticated signatures of an individual.

2. A signature verification method comprising:

a) obtaining two or more exemplar signatures from a verified individual constrained by two or more delimitations to form an exemplar library;

b) analyzing for each exemplar signature in the exemplar library the characteristics of the geometrical areas bounded by the exemplar signature string itself, residing between portions of the exemplar signature string or residing between the exemplar signature string and said one or more delimitations;

c) determining said geometrical areas which are correspondingly found in substantially each said exemplar signature of said exemplar library;

d) determining one or more mathematical relationship(s) between a plurality of corresponding geometrical areas within an exemplar signature that holds true for substantially each of said exemplar signatures in said exemplar library, thereby identifying archetypical delimited areas;

e) causing one or more unauthenticated signatures to be signed in a delimiting manner corresponding to the manner in which said exemplar signatures were delimitedly signed;

f) searching for said archetypical delimited areas determined in step d in said one or more unauthenticated signatures;

g) determining whether said archetypical delimited areas of said one or more unauthenticated signatures display the same mathematical relationship as said archetypical delimited areas with respect to said exemplar signatures; and

h) rejecting as non-authenticate unauthenticated signatures failing to display the same mathematical relationship(s) as said archetypical delimited areas with respect to said exemplar signatures.

3. The method of claim 2 wherein three or more delimitations are used to constrain the exemplar signatures.

4. The method of claim 2 wherein the signature verification method is used to identify a person from a signature.

5. The signature verification method of claim 2 wherein the geometrical areas generated in step b are based on a first type of geometric analysis, and after step c, undertaking a second type of geometric analysis to generate further sets of geometric areas to optimize the number of corresponding areas for a particular individual, wherein the optimized corresponding areas are used in step d to identify the archetypical delimited areas.

6. A signature verification method comprising:

a) obtaining two or more exemplar signature strings from a verified individual to form an exemplar library;

b) analyzing for each exemplar signature in the exemplar library the characteristics of the geometrical areas bounded by the exemplar signature string itself, residing between portions of the exemplar signature string or residing between the signature string and any signature string delimitation placed similarly in each of said exemplar signatures;

c) determining said geometrical areas which are correspondingly found in substantially each of said exemplar signatures of the exemplar library;

d) determining one or more mathematical relationship(s) between more than one said corresponding geometrical areas within an exemplar signature that holds true for substantially each of said exemplar signatures in said exemplar library, thereby identifying archetypical delimited areas;

e) obtaining one or more signature strings which are to be authenticated;

f) searching for said archetypical delimited areas in said one or more unauthenticated signatures;

g) determining whether said corresponding archetypical delimited areas of said one or more unauthenticated signatures display the same mathematical relationship(s) as said archetypical delimited areas with respect to said exemplar signatures; and

h) rejecting as non-authenticate unauthenticated signatures failing to display the same mathematical relationship as said archetypical delimited areas with respect to said exemplar signatures;

wherein the area encompassed by the perimeter of the entire signature string is not used as a corresponding geometrical area for purposes of determining the mathematical relationship(s) of step d.

7. The method of claim 6 wherein said mathematical relationship(s) between said two or more geometrical areas relates to the interrelationship between surface area.

8. The method of claim 6 wherein the signature verification method is used to identify a person from a signature.

9. A signature verification method comprising the steps of:

a) obtaining two or more exemplar signature strings from a verified individual to form an exemplar library;

b) generating a set of geometric areas based on a first type of geometric analysis for each exemplar signature in the exemplar library comprising areas of contiguous pixels enclosed by the exemplar signature string itself, residing between portions of the exemplar signature string itself, or residing between the exemplar signature string and one or more delimitations;

c) determining said geometrical areas which are correspondingly found in substantially each of said exemplar signatures of the exemplar library;

d) repeating steps b-c using one or more second type of geometric analysis to generate subsequent set(s) of geometric areas to optimize the number of corresponding areas for a particular individual;

e) determining one or more mathematical relationship(s) between more than one said optimized corresponding geometrical areas within an exemplar signature that holds true for substantially each of said exemplar signatures in said exemplar library, thereby identifying optimized archetypical delimited areas;

f) obtaining one or more signature strings which are to be authenticated;

g) searching for said optimized archetypical delimited areas in said one or more unauthenticated signatures;

h) determining whether said corresponding optimized archetypical delimited areas of said one or more unauthenticated signatures display the same mathematical relationship(s) as said archetypical delimited areas with respect to said exemplar signatures; and

i) rejecting as non-authenticate unauthenticated signatures failing to display the same mathematical relationship as said optimized archetypical delimited areas with respect to said exemplar signatures.

10. The method of claim 9 wherein the signature verification method is used to identify a person from a signature.