What's the science behind fingerprint scanners?

Bio-metrics are automated methods of recognizing a person based on a physiological or behavioral characteristic. Among the features measured are face, fingerprints, hand geometry, handwriting, iris, retinal, vein, and voice.

The scanner uses a light-sensitive microchip, either a CCD, charge-coupled device, or a CMOS image sensor, to produce a digital image. The computer analyzes the image automatically, selecting just the fingerprint, and then uses sophisticated pattern-matching software to turn it into a code.

The technique relies on capturing an optical image, essentially a photograph, and using algorithms to detect unique patterns on the surface, such as ridges or unique marks, by analyzing the lightest and darkest areas of the image.