A coding scheme for indexing multimodal biometric databases

In biometric identification systems, the identity associated with the input data is determined by comparing it against every entry in the database. This exhaustive matching process increases the response time of the system and, potentially, the rate of erroneous identification. A method that narrows the list of potential identities will allow the input data to be matched against a smaller number of identities. We describe a method for indexing large-scale multimodal biometric databases based on the generation of an index code for each enrolled identity. In the proposed method, the input biometric data is first matched against a small set of reference images. The set of ensuing match scores is used as an index code. The index codes of multiple modalities are then integrated using three different fusion techniques in order to further improve the indexing performance. Experiments on a chimeric face and fingerprint bimodal database indicate a 76% reduction in the search space at 100% hit rate. These results suggest that indexing has the potential to substantially improve the response time of multimodal biometric systems without compromising the accuracy of identification.