Data Acquisition:-Data collection involves use of sensors to detect & measure an individual’s physiological or behavioral characteristics. The biometric feature must have the following characteristics:-
(a) Universality, which means that every person should have the characteristic,
(b) Uniqueness, two persons should not have the same term or measurement of characteristic,
(c) Permanence, the characteristic should be invariant with time,
(d) Measurability, the characteristic can be quantified that is the origin of the
Cameras used in biometric systems are generally either CCD(charge couple device) or CMOS(combined metal oxide semiconductor) image sensors.CCD’s are comparatively more costlier than CMOS. The cost of CCD is nearly 2500 Rs. And CMOS is about 800 to 1000 Rs. Price depends on the resolution which reflects the accuracy of biometric system.
Transmission: -
Not all the biometric systems process and store data on the measuring device. Often measurement is made using relatively simple device to a computer or server for processing and/or storage. Depending on the system, the data may be relatively large and thus would need to be compressed for quick transfer. The compression algorithm needs to be selected carefully; otherwise it may introduce some artefacts that could impact the decision process.
In any image scanning Biometric system, JPEG compression is preferred due to the blockness it produces at high compression ratios. The data can also be transmitted to the database for storage as raw data.
Signal Processing:-
The signal processing unit uses features extraction algorithms to extract true biometric information from the sample in presence of noise introduced during data collection and transmission. Additional measurements are made if any flaw or corruption is noted, to ensure good quality.
Pattern matching involves comparing the feature sample to a stored sample. (The biometric data can be stored locally on the biometric data can be stored locally on the biometric device, some central database/server, or on a smart card issued to users.) The result of the comparison is sent to the decision system to determine the match.
Decision Making:-
The final step is the decision to accept or reject user, and is based on a security threshold. The threshold value is either a parameter of comparison process itself, or the system compares the resulting match value with the threshold value. If for example, in a system performing identity verification, the match value is equal to or higher than the threshold value, the user is accepted. In an identification system, acceptance might require a match value that is both higher than threshold value and higher than the second-best match by a specific amount.
Data Storage:-
After extracting the biometric features, the system stores and maintains the new master template. Choosing proper discriminating characteristics for categorizing records can facilitate future searches. The system stores the templates in one of four locations: a card, a server’s central database, a workstation, or an authentication terminal. If privacy is a concern, a card is the only choice because sensitive biometric data should not be stored (and potentially misused) in a central database.
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