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| Basics of Biometrics |  There are several biometric technologies in use today with a few more technologies being investigated in research laboratories worldwide. Nevertheless, all the technologies share a common process flow.
A sensor is required to get the biometric data that will then be processed by a processor which could be part of integrated system or a PC. The processing includes improving the data, removing noise and segmenting out the critical data. From such conditioned data, the unique features are then extracted and a templet is generated. This templet is the basis from which the uniqueness of the data is associated with the identity of the user. If the user is using the biometric system first time, the templet will be saved for future references. Also the other information associated with the user may be included.
User access to the system involves comparing the generated template against the reference of allowed user/users. If the matching is made against a claimed identity, the matching process will be a one to one comparison between the generated template and the stored reference template. Such a matching process is called a verification process.
There are many ways to claim an identity, such as by entering name, telephone number, PIN or password and using token such as smart card or contactless card. Another possible mode of matching is to compare the generated template with a list of reference templates of legitimate users. Such operation involves the matching process that is called an identification process. But not every biometric technology is suitable for identification. The following sections will discuss the common biometric technology such as face, fingerprint, hand geometry, iris, and voice.
All biometric systems consist of three basic elements:
• enrollment, or the process of collecting biometric samples from an individual, known as the enrollee, and the subsequent generation of his template
• templates, or the data representing the enrollee’s biometric
• matching, or the process of comparing a live biometric sample against one or many templates in the system’s database
Enrollment
Enrollment is the critical first stage for biometric authentication because enrollment generates a templet that will be used for all following matching. Typically, the device takes three samples of the same biometric and averages them to produce templet. Enrollment should take place under conditions similar to those that is expected during the everyday matching process. For example, if voice verification is used in an environment with background noise, the system’s first stage for biometric authentication must be provided in the same environment.
In addition to user and environmental issues, biometrics themselves continuously change. Many biometric systems account for these changes by constant averaging. Templates are averaged and updated each time the user authenticates.
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