Multispectral Fingerprint Image Acquisition

This chapter describes the principles of operation of a new class of fingerprint sensor based on multispectral imaging (MSI). The MSI sensor captures multiple images of the finger under different illumination conditions that include different wavelengths, different illumination orientations, and different polarization conditions. The resulting data contain information about both the surface and subsurface features of the skin. These data can be processed to generate a single composite fingerprint image equivalent to that produced by a conventional fingerprint reader, but with improved performance characteristics. In particular, the MSI imaging sensor is able to collect usable biometric images in conditions where other conventional sensors fail such as when topical contaminants, moisture, and bright ambient lights are present or there is poor contact between the finger and sensor. Furthermore, the MSI data can be processed to ensure that the measured optical characteristics match those of living human skin, providing a strong means to protect against attempts to spoof the sensor.