How do biometric systems work?
Biometrics systems work by recording and comparing biometric characteristics. In many cases, characteristics are recorded as images, but for speaker recognition a waveform is recorded, and for signature recognition, time series data. For efficiency reasons, rather than using recorded characteristics directly, it is usual to extract identifying features from the samples and encode these features in a form that facilitates storage and comparison.
When an individual first uses a biometric system, their identifying features are enrolled as a reference for future comparison. This reference may be stored in a central database or on a card (or both) depending on the needs of the application.
When biometric recognition is required, the individual 's biometric characteristics are recorded again. This time however, the identifying features are compared by the system with the stored reference to determine if there is a close match.
There are two modes for biometric recognition: verification and identification. In verification, an identity is claimed and the comparison process is limited to checking the reference corresponding to this identity. In identification, no claim of identity is necessary and the system searches its reference database to find if a stored reference matches the biometric characteristics recorded.
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