Methods and systems for slant compensation in handwriting and signature recognition
View Patent ↗Various computer-implemented methods are provided. One method for signature recognition includes identifying a vertical element of a signature and determining a tilt angle of the vertical element. Tilt angle is defined by a line that is approximately parallel to the vertical element. In addition, the method includes determining a tilt factor. Tilt factor is defined as a horizontal offset between the tilt angle and a reference tilt as a function of distance from a signature baseline. The method further includes altering the signature using the tilt factor and comparing the altered signature to known signature(s) to determine if the altered signature matches one of the known signature(s). Another method includes altering the signature using a predetermined tilt factor and comparing the altered signature to known signature(s). If the altered signature does not match one of the known signature(s), these steps may be repeated with different predetermined tilt factors.
1. A computer-implemented method comprising program instructions stored on a storage medium and executed by a processor for recognizing a signature, comprising:
first program instructions executable for identifying a vertical element of the signature;
second program instructions executable for determining a tilt angle of the vertical element, wherein the tilt angle is defined by a line that is approximately parallel to the vertical element;
third program instructions executable for determining a tilt factor, wherein the tilt factor is defined as a linear function in which a horizontal offset between the tilt angle and a reference tilt of a known signature varies with vertical distance from a signature baseline;
fourth program instructions executable for altering the signature using the tilt factor; and
fifth program instructions executable for comparing the altered signature to the known signature to determine if the altered signature matches the known signature.
2. The method of claim 1 , wherein the signature comprises a signature written on a digitizer with a stylus by a user, and wherein the digitizer and the stylus are arranged at different angles by the user.
3. The method of claim 1 , wherein the signature comprises a signature written on a tablet computer by a user.
4. The method of claim 1 , wherein the signature comprises a signature written by a user at a login prompt of a computer or a system.
5. The method of claim 1 , wherein the computer-implemented method is performed as the signature is being written by a user.
6. The method of claim 1 , wherein the known signature has been corrected for tilt.
7. The method of claim 1 , wherein said fourth program instructions executable for altering the signature does not include rotating the signature.
8. The method of claim 1 , wherein said fourth program instructions executable for altering the signature does not include segmenting the signature.
9. The method of claim 1 , wherein said fourth program instructions executable for altering the signature does not include normalizing a thickness of elements of the signature.
10. The method of claim 1 , wherein said fourth program instructions executable for altering the signature comprises determining a vertical distance between a portion of the signature and the signature baseline, identifying the horizontal offset corresponding to the vertical distance using the tilt factor, and applying the corresponding horizontal offset to the portion of the signature.
11. The method of claim 1 , further comprising, prior to executing said fifth program instructions for comparing the altered signature to the known signature, sixth program instructions executable for further altering the signature by applying a baseline correction to the signature, wherein the baseline correction is defined as a vertical offset between the signature baseline and a reference baseline of the known signature as a function of distance from a starting line that corresponds to a leftmost point of the signature.
12. A computer-implemented method comprising program instructions stored on a storage medium and executed by a processor for recognizing a signature, comprising:
first program instructions executable for altering the signature using a predetermined tilt factor, wherein the predetermined tilt factor is defined as a linear function in which a horizontal offset between a tilt angle of the signature and a reference tilt of a known signature varies with vertical distance from a signature baseline;
second program instructions executable for comparing the altered signature to one or more known signatures to determine if the altered signature matches one of the one or more known signatures, wherein if the altered signature does not match one of the one or more known signatures, the method further comprises:
third program instructions executable for altering the signature using a different predetermined tilt factor; and
fourth program instructions executable for comparing the different altered signature to the one or more known signatures to determine if the different altered signature matches one of the one or more known signatures.
13. The method of claim 12 , further comprising fifth program instructions executable for repeating said altering the signature using a different predetermined tilt factor and said comparing the different altered signature until the different altered signature matches one of the one or more known signatures.
14. The method of claim 12 , further comprising fifth program instructions executable for repeating said altering the signature using a different predetermined tilt factor and said comparing the different altered signature until the signature has been altered with a predetermined set of different predetermined tilt factors.
15. A computer-implemented method comprising program instructions stored on a storage medium and executed by a processor for normalizing handwriting, comprising:
first program instructions executable for identifying a vertical element of the handwriting;
second program instructions executable for determining a tilt angle of the vertical element, wherein the tilt angle is defined by a line that is approximately parallel to the vertical element;
third program instructions executable for determining a tilt factor, wherein the tilt factor is defined as a linear function in which a horizontal offset between the tilt angle and a reference tilt of a known signature of varies with vertical distance from a signature baseline; and
fourth program instructions executable for altering the handwriting using the tilt factor.
16. The method of claim 15 , further comprising fifth program instructions executable for acquiring the handwriting as input written on a digitizer with a stylus by a user, wherein the digitizer and the stylus are arranged at different angles by the user.
17. The method of claim 15 , further comprising fifth program instructions executable for acquiring the handwriting as input from a user using a tablet computer.
18. The method of claim 15 , further comprising fifth program instructions executable for analyzing the altered handwriting by performing one or more functions on the altered handwriting.
19. The method of claim 15 , further comprising fifth program instructions executable for repeating said identifying, said determining the tilt angle, and said determining the tilt factor at predetermined intervals to account for varying tilt within the handwriting.