Adaptation method for inter-person biometrics variability

• US 20070100622A1
• Filed: 10/31/2005
• Published: 05/03/2007
• Est. Priority Date: 10/31/2005
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Tavares, Clifford
• Granted Patent: US 7,788,101 B2
• Time in Patent Office: Days
• US Class Current: 704/250
• CPC Class Codes: G10L 17/06 Decision making techniques; Pattern matching strategies

Abstract

Embodiments of a system and method for verifying an identity of a claimant are described. In accordance with one embodiment, a feature may be extracted from a biometric sample captured from a claimant claiming an identity. The extracted feature may be compared to a template associated with the identity to determine the similarity between the extracted feature and the template with the similarity between them being represented by a score. A determination may be made to determine whether the identity has a correction factor associated therewith. If the identity is determined to have a correction factor associated therewith, then the score may be modified using the correction factor. The score may then be compared to a threshold to determine whether to accept the claimant as the identity. In accordance with a further embodiment, during enrollment of a subject in a biometric verification system, a feature may be extracted from a biometric sample captured from the subject requesting enrollment and a standard deviation for the feature may then be calculated. A determination may then be performed to determining whether the standard deviation of the feature is greater than a standard deviation of a centroid of a density function. If the standard deviation of the feature is greater than the standard deviation of the centroid, then a correction factor for the subject may be derived based on a trend line of the density function.

Claims

1. A method for verifying an identity of a claimant, comprising:

extracting a feature from a biometric sample captured from a claimant claiming an identity;

comparing the extracted feature to a template associated with the identity to determine the similarity between the extracted feature and the template, the similarity being represented by a score;

determining whether the identity has a correction factor associated therewith;

modifying the score using the correction factor if the identity is determined to have a correction factor associated therewith; and

comparing the score to a threshold to determine whether to accept the claimant as the identity.

2. The method of claim 1, wherein the biometric sample comprises speech.

3. The method of claim 1, wherein the correction factor is derived from a biometric sample captured from the claimed identity.

4. The method of claim 1, wherein the correction factor is retrieved from a correction factor data store.

5. The method of claim 1, wherein the correction factor is added to the score to modify the score.

6. The method of claim 1, wherein the correction factor has a negative value.

7. The method of claim 1, wherein the claimant is rejected if the score of the claimant exceeds the threshold.

8. A system for verifying an identity of a claimant, comprising:

a feature extraction component for extracting a feature from a biometric sample captured from a claimant claiming an identity;

a comparison component for comparing the extracted feature to a template associated with the identity to determine the similarity between the extracted feature and the template, the similarity being represented by a score, wherein the comparison component determines whether the identity has a correction factor associated therewith and modifies the score using the correction factor if the identity is determined to have a correction factor associated therewith; and

a decision component for comparing the score to a threshold to determine whether to accept the claimant as the identity.

9. The system of claim 8, wherein the biometric sample comprises speech.

10. The system of claim 8, wherein the correction factor is derived from a biometric sample captured from the claimed identity.

11. The system of claim 8, wherein the correction factor is retrieved from a correction factor data store.

12. The system of claim 8, wherein the correction factor is added to the score to modify the score.

13. The system of claim 8, wherein the correction factor has a negative value.

14. The system of claim 8, wherein the claimant is rejected if the score of the claimant exceeds the threshold.

15. A method, comprising:

extracting a feature from a biometric sample captured from a subject requesting enrollment;

calculating a standard deviation for the feature;

determining whether the standard deviation of the feature is greater than a standard deviation of a centroid of a density function; and

deriving a correction factor for the subject based on a trend line of the density function if the standard deviation of the feature is greater than the standard deviation of the centroid.

16. The method of claim 15, wherein the density function comprises a match score vs. standard deviation density function of a sample population.

17. The method of claim 15, wherein the correction factor is further derived from the difference between a mean score obtained from the centroid and a score for the subject derived from the trend line.

18. The method of claim 15, further comprising determining whether the standard deviation of the feature exceeds a threshold value, and using the threshold value in place of the standard deviation of the feature to derive the correction factor for the subject if the standard deviation of the feature exceeds the threshold value.

19. The method of claim 15, further comprising storing the correction factor in correction data store.

20. The method of claim 15, wherein the biometric sample comprises speech.