Method and apparatus for dynamic signature verification
AssigneeVisa International Service Association
InventorsEinar L. Asbo, Hardy Tichenor
Life of this patent
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Abstract
The subject invention relates to a new and improved method of dynamic signature verification. In accordance with the subject invention output signals, generated by a stylus, are normalized such that they are insensitive to the rotational position of the stylus with respect to the writer's grip. In operation, pressure measurements are sampled at discrete intervals and a normalization angle is calculated, representative of the average direction of the signature. Each sample is then assigned a vector length which is rotated by the normalization angle. The normalized samples are utilized to perform signature analysis.
Claims9
In a signature verification system including a stylus capable of sensing pressure in two orthogonal (x,y) directions and generating signals proportional thereto, a method of normalizing the signals generated by the stylus such that the result is insensitive to the rotational position of the stylus with respect to the writer's grip comprising the steps of:
- generating first and second distinct trains of output signals each of which is proportional to the forces exerted on the stylus in one of two orthogonal (x,y) directions;
- sampling the first and second trains of output signals at discrete intervals during a signature;
- computing an angle representative of the average direction of the signature;
- normalizing each sample by said computed angle;
- and
- comparing the normalized samples with a reference signature to verify the identity of the writer.
In a signature verification system including a stylus capable of sensing pressure in two orthogonal (x, y) directions, a method of normalizing the signals generated by the stylus such that the result is insensitive to the rotational position of the stylus with respect to the writer's grip comprising the steps of:
- generating first and second distinct trains of output signals, each of which is proportional to the forces exerted on the stylus in one of the two orthogonal (x,y) directions;
- sampling the first and second trains of output signals at discrete intervals during a signature;
- computing an angle representative of the average direction of all the samples in the signature;
- assigning each sample a vector length and angle;
- rotating the vector associated with each sample by the computed angle and calculating new values for each sample based on the rotated vector;
- and
- comparing the newly calculated values for each sample to a reference signature for verifying the identity of the writer.
A signature verification system comprising:
- a stylus;
- means, connected to said stylus, for generating first and second trains of output signals, each train being proportional to the forces exerted on the stylus in one of two orthogonal (x, y) directions;
- means for sampling said trains of output signals at discrete intervals during a signature;
- processor means for computing an angle representative of the average direction of a signature and for normalizing each sample by said angle;
- and
- means for comparing the normalized samples to a reference signature for verifying the identity of the writer.
Dependencies are inferred from the claim text.