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Master Thesis - Department of Computer Science

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A.6.3 Matching Score Computation<br />

Once the count <strong>of</strong> matched minutiae, NMM, is obtained, a matching score (represents<br />

the degree <strong>of</strong> match) is computed using one <strong>of</strong> the following formulas:<br />

MS =<br />

√<br />

NMM<br />

,<br />

P ∗ Q<br />

(A.38)<br />

MS = 2NMM<br />

. (A.39)<br />

P + Q<br />

where P and Q are the number <strong>of</strong> minutiae features in fingerprints P and Q, used for<br />

matching. We also used a normalized score, which takes into account the closeness<br />

(in the Euclidean sense) <strong>of</strong> paired minutiae features. This is computed as:<br />

NMS = MS<br />

D<br />

NMM +1<br />

. (A.40)<br />

where, D is the sum <strong>of</strong> all the Euclidean distances <strong>of</strong> the paired minutiae obtained<br />

after registration.<br />

A.7 Experimental Results<br />

The following databases are used for evaluating our fingerprint recognition system,<br />

• DBA consists <strong>of</strong> 10 subjects each having 8 samples (FVC 2002 Database [1]).<br />

• DBB consists <strong>of</strong> 10 subjects each having 8 samples (FVC 2004 Database [2]).<br />

Table A.1: Accuracy (in Percentage Accuracy) for DBA and DBB.<br />

Case DBA DBB<br />

Case A 88.75 69.00<br />

Case B 90.00 70.00<br />

The recognition performance for two databases are tabulated in Table A.1. The<br />

accuracies for each database is calculated for two different cases, where the matching<br />

score is calculated using : Case A Eqn. (A.40), and Case B Eqn. (A.38). Case<br />

A provides a stricter check than case B by taking Euclidean Distance (D) under<br />

consideration. In all cases, only one sample per subject is used for training and rest<br />

<strong>of</strong> the images are used for recognition.<br />

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