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1. WO2009011661 - METHOD AND DEVICE FOR DETERMINING A SIMILARITY VALUE BETWEEN MINUTIAE TEMPLATES

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Claims

What is claimed is:

1. A method for determining a similarity value between a first minutiae template and a second minutiae template, the method comprising:
determining a first cluster characteristic for each first cluster of a plurality of first clusters, each first cluster comprising a plurality of first minutiae comprised in the first minutiae template;
determining a second cluster characteristic for each second cluster of a plurality of second clusters, each second cluster comprising a plurality of second minutiae comprised in the second minutiae template;
determining the similarity value based on the first cluster characteristics and the second cluster characteristics.

2. The method of claim 1 ,
wherein the cluster characteristic comprises information about the shape of each cluster.

3. The method of claim 2,
wherein the cluster characteristic comprises information about the convex hull of each cluster and/or information about the position about the centroid of each cluster.

4. The method of any one of the claims 1 to 3,
wherein the cluster characteristic comprises information about the size of each cluster.

5. The method of any one of the claims 1 to 4,
wherein the cluster characteristic comprises information about the minutiae included in each cluster.

6. The method of claim 5,
wherein the cluster characteristic comprises at least one of the following information elements:
a number of the minutiae included in each cluster;
a density of the minutiae included in each cluster;
an average ridge number between two adjacent minutiae in each cluster;
position of a fingerprint core;
number of fingerprint cores in each cluster;
position of a fingerprint delta;
number of fingerprint deltas in each cluster.

7. The method of any one of the claims 1 to 6, further comprising:
determining a plurality of first clusters, each first cluster comprising a plurality of first minutiae comprised in the first minutiae template.

8. The method of any one of the claims 1 to 7, further comprising:
determining a plurality of second clusters, each second cluster comprising a plurality of second minutiae comprised in the second minutiae template.

9. The method of any one of the claims 1 to 8,
wherein the determining the similarity value comprises determining a weighted sum of the differences between the first cluster characteristics and the second cluster characteristics; and
wherein the method further comprises determining a plurality of cluster similarity values between the first clusters and the second clusters using the weighted sum.

10. The method of any one of claims 1 to 9, further comprising
determining a first relative distance information for the plurality of first clusters, wherein the first relative distance information comprises relative distance between nearest centorids of the plurality of first clusters; and
determining a second relative distance information for the plurality of second clusters, wherein the second relative distance information comprises relative distance between nearest centorids of the plurality of second clusters.

11. The method of claim 10,
wherein the determining the similarity value between the first minutiae template and the second minutiae template further comprises determining a weighted sum of the differences between the first relative distance information and the second relative distance information.

12. The method of any one of the claims 1 to 11 ,
wherein the second minutiae template is an enrolment minutiae template of a certified user.

13. The method of any one of the claims 1 to 12, further comprising:
determining a first pair of matched minutiae of a first cluster of the plurality of first clusters and a second cluster of the plurality of second clusters; and
determining a second pair of matched minutiae of the first cluster of the plurality of first clusters and the second cluster of the plurality of second clusters by matching the nearest neighbour minutiae of the matched minutia of the first pair of matched minutiae in the first cluster and the nearest neighbour minutiae of the matched minutia of the first pair of matched minutiae in the second cluster.

14. The method of claim 13 , further comprising:
selecting a pair of matched minutiae with respect to a predefined matching criterion from the first pair of matched minutiae and the second pair of matched minutiae as a reference pair of matched minutiae; and
carrying out an alignment of the first minutiae template and the second minutiae template using the reference pair of matched minutiae.

15. The method of any one of the claims 1 to 14,
wherein a first part of the method is carried out by a first processor; and
wherein a second part of the method is carried out by a second processor, the second part of the method being different from the first part of the method.

16. The method of claim 15 ,
wherein the second processor uses results of the first processor for carrying out the second part of the method.

17. The method of claim 15 or 16, further comprising:
transmitting results of the second part of the method from the second processor to the first processor.

18. The method of any one of the claims 15 to 17,
wherein the first processor uses the results of the second part of the method for carrying out the first part of the method.

19. The method of any one of the claims 15 to 18,
wherein the results of the second part of the method transmitted to the first processor is non-confidential information.

20. The method of claim 19,
wherein the results of the second part of the method transmitted to the first processor comprises relative information between the minutiae of the first minutiae template or the second minutiae template.

21. The method of any one of the claims 15 to 20,
wherein the first processor is an external processor to the second processor.

22. The method of any one of the claims 15 to 21 ,
wherein the second processor is a trusted processor.

23. The method of claim 22,
wherein the second processor is a portable processing device.

24. The method of any one of the claims 15 to 23 ,
wherein the first part of the method comprises open portions of the method; and
wherein the second part of the method comprises confidential portions of the method.

25. The method of any one of the claims 15 to 24,
wherein the processes provided for the first part of the method and the processes provided for second part of the method are determined in accordance with a predefined load sharing criterion.

26. A device for determining a similarity value between a first minutiae template and a second minutiae template, the device comprising:
a first cluster characteristic determination unit for determining a first cluster characteristic for each first cluster of a plurality of first clusters, each first cluster comprising a plurality of first minutiae comprised in the first minutiae template;
a second cluster characteristic determination unit for determining a second cluster characteristic for each second cluster of a plurality of second clusters, each second cluster comprising a plurality of second minutiae comprised in the second minutiae template;
a similarity determination unit for determining the similarity value using the first cluster characteristics and the second cluster characteristics.

27. The device of claim 26,
wherein the cluster characteristic comprises information about the shape of each cluster.

28. The device of claim 27,
wherein the cluster characteristic comprises information about the convex hull of each cluster and/or information about the position about the centroid of each cluster.

29. The device of any one of claims 26 to 28,
wherein the cluster characteristic comprises information about the size of each cluster.

30. The device of any one of claims 26 to 29,
wherein the cluster characteristic comprises information about the minutiae included in each cluster.

31. The device of claim 30,
wherein the cluster characteristic comprises at least one of the following information elements:
a number of the minutiae included in each cluster;
a density of the minutiae included in each cluster;
an average ridge number between two adjacent minutiae in each cluster;
position of a fingerprint core;
number of fingerprint cores in each cluster;
position of a fingerprint delta;
number of fingerprint deltas in each cluster.

32. The device of any one of claims 26 to 31 , further comprising:
a first cluster determination unit for determining a plurality of first clusters, wherein each first cluster comprises a plurality of first minutiae comprised in the first minutiae template.

33. The device of any one of claims 26 to 32, further comprising:
a second cluster determination unit for determining a plurality of second clusters, wherein each second cluster comprises a plurality of second minutiae comprised in the second minutiae template.

34. The device of any one of claims 26 to 33,
wherein the similarity determination unit being configured to determine the similarity value comprises being configured to determine a weighted sum of the differences between the first cluster characteristics and the second cluster characteristics; and
wherein the similarity determination unit being configured to determine the similarity value further comprises being configured to determine a plurality of cluster similarity values between the first clusters and the second clusters using the weighted sum.

35. The device of any one of claims 26 to 34, further comprising
a first relative distance information determination unit for determining a first relative distance information for the plurality of first clusters, wherein the first relative distance information comprises relative distance between nearest centorids of the plurality of first clusters; and
a second relative distance information determination unit for determining a second relative distance information for the plurality of second clusters, wherein the second relative distance information comprises relative distance between nearest centorids of the plurality of second clusters.

36. The device of claim 35,
wherein the similarity determination unit being configured to determine the similarity value further comprises being configured to determine a weighted sum of the differences between the first relative distance information and the second relative distance information.

37. The device of any one of the claims 26 to 36,
wherein the second minutiae template is an enrolment minutiae template of a certified user.

38. The device of any one of the claims 26 to 37, further comprising a matched minutiae determination unit, wherein the matched minutiae determination unit is configured to determine a first pair of matched minutiae of a first cluster of the plurality of first clusters and a second cluster of the plurality of second clusters; and
determine a second pair of matched minutiae of the first cluster of the plurality of first clusters and the second cluster of the plurality of second clusters by matching the nearest neighbour minutiae of the matched minutia of the first pair of matched minutiae in the first cluster and the nearest neighbour minutiae of the matched minutia of the first pair of matched minutiae in the second cluster.

39. The device of claim 38, further comprising: a reference minutiae selection unit for selecting a pair of matched minutiae with respect to a predefined matching criterion from the first pair of matched minutiae and the second pair of matched minutiae as a reference pair of matched minutiae; and
a template alignment unit for carrying out an alignment of the first minutiae template and the second minutiae template using the reference pair of matched minutiae.

40. The device of any one of the claims 26 to 39,
wherein the device comprises a first processor and a second processor.

41. The device of claim 40,
wherein the first cluster characteristic determination unit and the second cluster determination unit are comprised in the first processor.

42. The device of claim 40,
wherein the similarity determination unit is comprised in the second processor.

43. The device of claim 40,
wherein the first processor is an external processor to the second processor.

44. The device of claim 40,
wherein the second processor is a trusted processor.

45. The device of claim 40, further comprising
a load sharing determination unit for determining the amount of information to be processed in the first processor and the second processor.