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What is the biometric fingerprint attendance system?

  • Author:HFSecurity
  • Release on :2019-07-29

Through special photoelectric conversion equipment and computer image processing technology, fingerprint attendance system can collect, analyze and compare the living fingerprint, which can quickly and accurately identify individual identity.The system mainly includes fingerprint image acquisition, fingerprint image processing, feature extraction, feature value comparison and matching.

Modern electronic integrated manufacturing technology makes fingerprint image reading and processing equipment miniaturized, and the rapid development of personal computer computing speed provides the possibility of fingerprint comparison operation on microcomputer or even single-chip microcomputer, while excellent fingerprint processing and comparison algorithm ensures the accuracy of the identification results.
The network fingerprint attendance system is composed of database server, application server, management computer, fingerprint attendance machine (or fingerprint reading head + access control controller). The core of fingerprint attendance system is fingerprint attendance machine.

The bumps and bumps in the skin on the inside surfaces of our hands, our fingers, our feet and our toes create a variety of patterns.The presence of these lines adds friction to the surface of the skin, allowing us to lift heavy objects with our hands.It has also been noted that the patterns, breakpoints and intersections of these skin patterns, including fingerprints, are different, that is, unique.By virtue of this uniqueness, we can match a person to his fingerprints and verify his true identity by comparing his fingerprints with those that have been preserved in advance.This kind of identification technology based on the physical characteristics of the human body is called biometrics, fingerprint identification is a kind of biometrics.

From the practical point of view, fingerprint identification technology is superior to other biometrics.That's because fingerprints are widely recognized for being different and essentially unchanged for life.

The application of the earliest fingerprint identification system and the detection of criminal suspects by the police has a history of more than 30 years, which lays a good technical foundation for the research and practice of fingerprint identification.In particular, fingerprint identification system has reached the stage of convenient operation, accurate and reliable, moderate price, and is gradually applied in the civil market.

Automatic fingerprint identification technology is moving from science fiction and Hollywood movies to our real life. Maybe one day, you don't need to carry a bunch of keys with you.You don't have to memorize that pesky password, you can use your fingerprint to withdraw money and log in to your computer.Believe this day, not too far away.

System Composition

Fingerprint collection equipment, the most commonly used imaging equipment is divided into two categories: optical, crystal sensors.

Optical imaging devices have the longest history, dating back to the 1970s.Optical imaging equipment is based on the principle of total reflection of light (FTIR).The amount of light that hits a glass surface pressed with a fingerprint is captured by a CCD, depending on the depth of the ridges and valleys pressed on the glass surface and the amount of grease and moisture between the skin and the glass.After the light enters the valley through the glass, it will be completely reflected at the interface between the glass and the air, and the light will be reflected to the CCD. However, the light that hits the ridge will not be completely reflected, but absorbed or diffused to other places by the contact surface between the ridge and the glass. In this way, the image of fingerprint will be formed on the CCD.

Due to the innovation of optical equipment, the volume of equipment has been greatly reduced.In the mid - '90s, the sensor could be packed in a 6x3x6-inch box, and in the near future a smaller device would be 3x1x1-inch.These advances depend on the development of multiple optical technologies rather than the development of the FTIR.For example, a fiber beam can be used to obtain a fingerprint image.A fiber beam hits the fingerprint's surface vertically. It illuminates the fingerprint and detects reflected light.Another solution is to install the surface containing a miniature prism matrix on an elastic plane. When the finger presses on the surface, the pressure on the ridge and valley will change the surface of the miniature prism. These changes are reflected by the light of the prism.

Crystal sensors are new to the market, although they have been in the technical literature for nearly 20 years.These planes, which contain tiny crystals, are mapped using a variety of techniques.The most common silicon capacitive sensors are designed to capture fingerprints using electronic measurements.About 100,000 capacitive sensors can be combined on a semiconductor metal array with an insulated surface on the outside, and when a user's finger is placed on it, the skin forms the other side of the capacitor array.The capacitance of a capacitor is reduced by the distance between the conductors, the distance between the ridge (near) and the valley (far) from the other pole.Another type of crystal sensor is pressure-sensitive, with a top layer of elastic pressure-sensitive dielectric material on the surface. They are converted into corresponding electronic signals according to the surface topography (concave and convex) of the fingerprint.Other crystal sensors include a temperature sensor that detects a fingerprint image by sensing the difference in temperature between the ridge pressed on the device and the one away from the device valley.

Fingerprint comparison algorithm (including fingerprint image processing, feature extraction, comparison and matching)

In the fingerprint comparison algorithm, there are two main concepts, verification and identification;Validation is what we call the 1:1 algorithm, and the argument is the 1: N algorithm.At the same time, there are two important parameters for fingerprint matching algorithm: error rate and rejection rate.


Verification is the process of matching a fingerprint from a field to a registered fingerprint to confirm an identity.As a prerequisite for verification, his or her fingerprint must have been registered in the fingerprint database.A fingerprint is stored in a compressed format and associated with its name or ID (PIN).After that, the identification is verified at the scene of comparison, and then the system's fingerprint is compared with the fingerprint collected at the scene to prove that the identification is legal.The test answers the question, "is he who he says he is?"This is the approach that is most often used in applications.

On discerniblile

Identification is to compare the fingerprints collected at the scene with those in the library of fingerprint data one by one and find out the matching fingerprints at the scene.It's also called "one-to-many matching."The test answers the question, "who is he?"Identification is mainly used in the traditional field of criminal fingerprint matching.The fingerprints of an unidentified person are compared with those of someone with a criminal record in the database to determine if that person has a criminal record.

Error rate and rejection rate

Because the computer processing fingerprint only involves some limited information of fingerprint, and the matching algorithm is not an exact match, the result can not guarantee 100% accuracy.The identification rate is an important measure of fingerprint attendance system.It is mainly composed of two parts, the rate of rejection (FRR) and the rate of error (FAR).We can adjust these two values for different purposes.FRR and FAR are inversely proportional.This number is expressed in terms of 0-1.0 or percentage.