Person authentication systems that use a single biometric trait often have to contend with noisy sensor data, restricted degrees of freedom and unacceptable error rates. Attempting to improve the performance of individual matcher in such situations may not prove to be effective because of these inherent problems. A robust identification system may require fusion of several modalities because ambiguities in one modality may be compensated by another modality. This book addresses the problem of biometric fusion in verification systems. It begins with an introduction to face, speech and...