Encyclopedia of Computer Science and Technology

48 biometricsvariety of biometric scanners that take Bertillon’s ideas to amuch more detailed level.TechnologiesIn general, biometric scanning involves four steps: thecapture of an image using a camera or other device, theextraction of key features from the image, the creation ofa template that uniquely characterizes the person beingscanned, and the matching of the template to stored templatesin order to identify the person.There are several possible targets for biometric scanning,including the following areas:Facial ScanningFacial scanning uses cameras and image analysis softwarethat looks at areas of the human face that change littleduring the course of life and are not easily alterable, suchas the upper outline of the eye sockets and the shape ofthe cheekbones. Researchers at MIT developed a series ofabout 125 grayscale images called eigenfaces from whichfeatures can be combined to characterize any given face.The template resulting from a scan can be compared withthe one on file for the claimed identity, and coefficientsexpressing the degree of similarity are calculated. Varianceabove a specified level results in the person being rejected.Facial scanning is often viewed as less intrusive than theuse of fingerprints, and it can also be applied to surveillanceimages.However, iris scanning involves the front of the eye and ismuch less intrusive, and the person being scanned needsonly to look into a camera.Voice ScanningVoice scanning and verification systems create a “voiceprint”from a speech sample and compare it to the voiceof the person being verified. It is a quick and nonintrusivetechnique that is particularly useful for remote transactionssuch as telephone access to banking information.Behavioral BiometricsBiometrics are essentially invariant patterns, and these canbe found in behavior as well as in physical features. One ofthe most promising techniques (recently patented) analyzesthe pace or rhythm of a person’s typing on a keyboard andgenerates a unique numeric code. A similar approach mightbe applicable to mouse usage.Applications of BiometricsDue to the expense of the equipment and the time involvedin scanning, biometrics were originally used primarily inverifying identity for people entering high-security installations.However, the development of faster and less intrusivetechniques, combined with the growing need to verify usersof banking (ATM) and other networks has led to a growingFinger ScanningFinger scanning involves the imaging and automatic analysisof the pattern of ridges on one or more fingertips. Unliketraditional fingerprinting, the actual fingerprint is notsaved, but only enough key features are retained to providea unique identification. This information can be stored in adatabase and also compared with full fingerprints stored inexisting databases (such as that maintained by the FederalBureau of Investigation). Finger scanning can meet withresistance because of its similarity to fingerprinting and theassociation of the latter with criminality.Hand GeometryThis technique measures several characteristics of thehand, including the height of and distance between thefingers and the shape of the knuckles. The person beingscanned places the hand on the scanner’s surface, aligningthe fingers to five pegs. Hand-scanning is reasonably accuratein verifying an individual compared to the templateon file, but not accurate enough to identify a scan from anunknown person.Iris and Retina ScanningThese techniques take advantage of many unique individualcharacteristics of these parts of the eye. The scannedcharacteristics are turned into a numeric code similar to abar code. Retina scanning can be uncomfortable because itinvolves shining a bright light into the back of the eye, andhas generally been used only in high-security installations.A portable iris recognition scanner being demonstrated at the Biometrics2004 exhibition and conference in London. (Ian Waldie/Getty Images)