Biometric systems the basic functional diagram of a biometric system the basic functional diagram of a biometric system the diagram on the line shows a simple functional diagram of a biometric system. The principal operations that a system can carry out are inscription and to examine. During the biometric information of inscription of an individual are stored, during the biometric information of test are detected and compared with stored. The first block (probe) is the interface between reality and our system; it must acquire all given necessary.



The majority of times it is a system of frame grabbing, but it can change according to characteristics' which we want to consider. The second block carries out any pretreatment necessary: it must remove worked objects of the probe, to increase the entry (for example removing a certain noise), to employ a certain kind of standardization, etc In the third block we must extract the devices which we have need. This stage is really important: we must choose who comprises to extract and how. Moreover we must do it with a certain effectiveness (it cannot take hours!).

After that, we can have a vector of the numbers or an image with the particular properties: all these data are employed to create a gauge. A gauge is a synthesis of all characteristics which we could extract starting from the source, it must be as short as possible (to improve the effectiveness) but we cannot throw details too much, of this fact loosening the capacity of discrimination. Then the behavior of the changes of system according to what was required. Then, if it carries out the inscription, then the gauge is simply stored some share (it can be inside on a chart or in a data base).

If it carries out the matched phase, the gauge obtained passed to bouveteuse which compares it with other existing gauges, considering the distance between them employing any algorithm (for example distance the Hamming one). The decision that the bouveteuse one took is sent like output, so that it can be employed for any goal (for example it can allow a purchase or the entry in a restricted sector).