Method of automated signature verification
First Claim
1. A method of handwritten signature verification, comprising the steps ofreceiving a plurality of handwritten template signature;
- defining a template feature vector for each of said template signatures;
performing a vector comparison between each pair of said template feature vectors so as to determine a plurality of template-template distances;
selecting one of said template-template distances other than a minimum or a maximum;
constructing a bit vector in response to each template feature vector and training a neural network in response to said bit vectors;
receiving a handwritten test signature;
defining a test feature vector in response to said test signature;
inputting said test feature vector to said neural network and generating a derived feature vector, different from said test feature vector, in response thereto;
performing a vector comparison between said derived feature vector and each one of said template feature vectors so as to determine a plurality of test-template distances;
determining a minimum one of said plurality of test-template distances; and
verifying said test handwritten signature if said minimum one of said test-template distances is less than or equal to said selected one of said template-template distances.
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Accused Products
Abstract
A method of automated signature verification, in which a test signature, e.g., a signature entered by an operator, may be preprocessed and examined for test features. The test features may be compared against features of a set of template signatures, and verified in response to the presence or absence of the test features in the template signatures. The test signature may be preprocessed, so as to normalize it and remove artifacts which are irrelevant to verification. The features of the template signatures may be determined and stored in an associative memory or a data structure with associative memory capabilities, e.g., a discrete Hopfield artificial neural network. The method of verification may be adjusted to greater or lesser sensitivity in response to external conditions.
276 Citations
32 Claims
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1. A method of handwritten signature verification, comprising the steps of
receiving a plurality of handwritten template signature; -
defining a template feature vector for each of said template signatures; performing a vector comparison between each pair of said template feature vectors so as to determine a plurality of template-template distances; selecting one of said template-template distances other than a minimum or a maximum; constructing a bit vector in response to each template feature vector and training a neural network in response to said bit vectors; receiving a handwritten test signature; defining a test feature vector in response to said test signature; inputting said test feature vector to said neural network and generating a derived feature vector, different from said test feature vector, in response thereto; performing a vector comparison between said derived feature vector and each one of said template feature vectors so as to determine a plurality of test-template distances; determining a minimum one of said plurality of test-template distances; and verifying said test handwritten signature if said minimum one of said test-template distances is less than or equal to said selected one of said template-template distances. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for determining whether a first person is a particular individual, said method comprising the steps of
storing a plurality of template features for each of a plurality of template signatures of the particular individual, each of said template features representing a selected characteristic of one of said template signatures; -
performing a comparison between each pair of said sets of template features so as to determine a plurality of template-template distances; selecting one of said template-template distances other than a minimum or a maximum; training a neural network in response to said sets of template features; providing a plurality of test features for a test signature made on a signature transducer by said first person, each of said test features representing a selected characteristic of said test signature; inputting said set of test features to said neural network and generating a set of derived features, different from said set of test features, in response thereto; performing a vector comparison between said derived feature vector and each one of said template feature vectors so as to determine a plurality of test-template distances; selecting one of said plurality of test-template distances; and generating a signal indicating a match if said selected one of said test-template distances is less than or equal to said selected one of said template-template distances. - View Dependent Claims (14)
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15. Apparatus for handwritten signature verification, comprising
a pen tablet; -
a processor coupled to said pen tablet and disposed for receiving a plurality of template signatures and a test signature; said processor comprising means for defining a template descriptor for each said template signatures and a test descriptor for said test signature; said processor being disposed for comparing each pair of said template descriptors, generating a plurality of template-template distances in response thereto, and selecting one of said plurality of template-template distances other than a maximum; an associative memory, said associative memory disposed for storing each of said template descriptors, for being addressed using said test descriptor, and for retrieving a derived descriptor in response to said template descriptors and said test descriptor; said processor comprising means for comparing said derived descriptor against each said template descriptor, generating a plurality of test-template distances in response thereto, selecting one of said plurality of test-template distances, and comparing said one of said plurality of test-template distances against said one of said plurality of template-template distances; and means for displaying an output of said processor responsive to said means for comparing said one of said plurality of test-template distances against said one of said plurality of template-template distances. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of handwritten signature verification, comprising the steps of
receiving a plurality of handwritten template signatures; -
generating a template feature vector for each one of said template signatures; determining a template-template distance between each pair of said template feature vectors; selecting one of said template-template distances in response to a statistical measure of said template-template distances; storing said template feature vectors in an associative memory; receiving a handwritten test signature; generating a test feature vector for said test signature; generating a derived feature vector in response to said associative memory and said test feature vector; determining a test-template distance between said derived feature vector and each one of said template feature vectors; selecting one of said plurality of test-template distances; verifying said test signature in response to a comparison of said selected one of said test-template distances and said selected one of said inter-template distances. - View Dependent Claims (26, 27, 28, 29)
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30. Apparatus for determining whether a first person is a particular individual, said apparatus comprising
a first memory including a template descriptor for each of a plurality of template signatures of the particular individual, and a plurality of template-template distances between each pair of said template descriptors; -
a second memory including a test descriptor for a test signature made on a signature transducer by said first person; an associative memory, said associative memory disposed for storing each of said template descriptors, for being addressed using said test descriptor, and for retrieving an derived descriptor different from said test descriptor; a third memory including a plurality of test-template descriptors between said derived descriptor and each one of said template descriptors; a processor coupled to said first memory, said second memory, and said third memory and disposed for comparing a selected one of said test-template distances with a selected one of said template-template distances other than a maximum thereof; and means for displaying a match only if said said selected test-template distance is less than of said selected template-template distance. - View Dependent Claims (31, 32)
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Specification