Iris is a fabric-like ring with various colors in the pupil of the eye. Each iris contains a unique structure, which is based on features such as crown, lens, filaments, spots, structures, pits, rays, wrinkles and stripes. It is said that no two irises are the same. Technical advantages of iris: 1, which is convenient for users to use;

2. It may be the most attractive biometric technology; 3. No physical contact is required; Disadvantages of iris technology: 1. Disadvantages of iris technology:

One of the most important shortcomings is that it has not been tested. At present, the iris recognition system only uses statistical principle to carry out small-scale experiments, and has not passed the test of uniqueness authentication in the real world. 3. It is difficult to miniaturize the image acquisition equipment;

4, need expensive camera focusing, the lowest price of such a camera is 7000 dollars; 5, the lens may produce image distortion, reducing accessibility; 6, black eyes are extremely difficult to read; 7, need a good light source. Second, retinal recognition technology

The retina is also a feature for biometric identification. Some people even think that retina is more unique than iris. Retinal recognition technology needs laser irradiation on the back of eyeball to obtain the uniqueness of retinal features.

Advantages of retina technology:

1. Retina is an extremely fixed biological feature, which will not be worn, aged or affected by diseases. 2. Users don't need to touch the equipment directly;

It is the most difficult system to cheat, because the retina is invisible, so it will not be forged. Defect of retina recognition: 1, untested;

2. Laser irradiation on the back of eyeball may affect the health of users, which needs further study; 3. For consumers, retina technology is not attractive; 4. It is difficult to reduce the cost further.

2. It may be the most attractive biometric technology; 3. No physical contact is required; Disadvantages of iris technology:

One of the most important shortcomings is that it has not been tested. At present, the iris recognition system only uses statistical principle to carry out small-scale experiments, and has not passed the test of uniqueness authentication in the real world. 3. It is difficult to miniaturize the image acquisition equipment;

4, need expensive camera focusing, the lowest price of such a camera is 7000 dollars; 5, the lens may produce image distortion, reducing accessibility; 6, black eyes are extremely difficult to read; 7, need a good light source. Third, facial recognition.

Face recognition technology recognizes facial features and their relationships. The recognition technology based on these unique features is very complex, which requires artificial intelligence and machine knowledge learning system. The two technologies used to capture facial images are standard video and thermal imaging technology. Standard video technology shoots a face image or a series of images through a standard camera, records some core points (such as eyes, nose and mouth) and their relative positions after capture, and then forms a template; Thermal imaging technology produces facial images by analyzing the hot lines generated by the blood of facial capillaries. Unlike video cameras, thermal imaging technology does not need good light source conditions, so it can be used even in the dark. An algorithm, a neural network system and a transformation mechanism can turn fingerprint images into digital signals, and finally produce matched or mismatched signals.

Advantages of facial recognition:

1. Face recognition is non-contact, and users don't need to touch the device directly; Disadvantages of facial recognition:

1, although a desktop video camera can be used, only a more advanced camera can shoot facial images at high speed and effectively;

2. The position of the user's face and the surrounding light environment may affect the accuracy of the system; Most students of biometrics realize that facial recognition is the most inaccurate and gullible.

4. The improvement of face recognition technology depends on the improvement of feature extraction and comparison technology, and the equipment for collecting images is much more expensive than technology;

5. For the changes of human face, such as hair, ornaments, aging and other changes that need artificial intelligence compensation, the machine learning function must constantly compare the previously obtained image with the current image; Improve core data and make up for subtle differences;

6. It is difficult to reduce the cost further, and it is necessary to sell high-quality equipment at an expensive cost. Fourth, signature recognition.

Signature has been used as a means of identity authentication for hundreds of years, and we are all familiar with signing in the form of a bank as a sign of identity. Digitizing a signature is a process of measuring the action of the image itself and the whole signature-different speeds, sequences and pressures between each letter and between letters. Like speech recognition, signature recognition is also a behavior measurement.

Advantages of signature recognition:

1, easily accepted by the public, is a recognized identification technology;

The signature will change with the change of lifestyle; 2. It is inconvenient to use online;

3. The handwriting board for signature is complex in structure and expensive, because the resolution is very different from the touchpad of notebook computer, so it is difficult to combine them technically; 4. It is difficult to miniaturize the size. V. Speech recognition technology

Speech recognition is also a behavior recognition technology, and the recognition equipment constantly measures and records the waveform and change of sound. Speech recognition is based on the exact matching between the collected speech and the registered speech template. Advantages of speech recognition:

Speech recognition is also a non-contact recognition technology, which is naturally acceptable to users. Disadvantages of speech recognition:

As a behavior recognition technology, the range of sound changes is too large to match accurately;

The sound will change with the volume, speed and sound quality (for example, when you have a cold), which will affect the results of collection and comparison; It is easy to deceive the speech recognition system with the voice recorded on the tape; Hi-fi microphones are expensive.

Six, fingerprint identification system

As an identification technology, fingerprint identification has a long history and a solid market backing. It is generally believed that by analyzing the global features and local features of fingerprints, such as ridges, valleys and endpoints, bifurcation points or bifurcation points, the feature values extracted from fingerprints can be very detailed and a person's identity can be confirmed.

On average, each fingerprint has several unique and measurable feature points, each feature point has about seven features, and our ten fingers produce at least 4900 independently measurable features.

The two main technologies used to collect fingerprint images are optical technology and capacitance technology. Optical technology needs a light source to reflect from the prism and press on the finger of a camera. The light illuminates the fingerprint and collects the fingerprint. Using the semiconductor technology of capacitance technology, the ridges and valleys of the finger pressed on the acquisition head produce different capacitances between the finger epidermis and the chip, and the chip obtains a complete fingerprint by measuring different capacitance fields in the space. Because the chip of capacitance technology is expensive, and the size of the chip is equivalent to the size of a finger, several companies try to introduce chips smaller than fingerprints and only collect some fingerprints. Using this collection method, the user's finger position must be very accurate, and only a part of the fingerprint is used, but not all fingerprints can be collected.

Capacitance acquisition head is susceptible to interference: 60HZ cable interference, interference when the user touches it, electrical interference inside the fingerprint collector, etc. The last problem of capacitance acquisition head is reliability. Whether it is electrostatic interference, salt or other dirt in sweat or finger wear, it will make it difficult for the collection head to read fingerprints. In fact, optical acquisition provides a more effective solution. With the continuous progress of optical imaging technology, capacitive scheme is dwarfed by the impeccable performance and relatively low price of optical fingerprint collector. Advantages of fingerprint identification:

1. Fingerprint is a unique feature of human body, and its complexity is enough to provide sufficient features for authentication; 2. If you want to increase accessibility, you only need to register more fingerprints and identify more fingers, up to ten, and each fingerprint is unique;

3. The speed of scanning fingerprints is very fast and it is very convenient to use;

4. When reading fingerprints, users must contact their fingers with the fingerprint collection head, and direct contact with the fingerprint collection head is the most effective way to read human biological characteristics.

6. The fingerprint collection head can be miniaturized and the price will be lower; Disadvantages of fingerprint identification:

1, some people or some groups have few fingerprint features, which makes imaging difficult;

2. In the past, some people were afraid of "putting fingerprints on records" because criminal records needed fingerprints.

3. In fact, the current fingerprint authentication technology can only store the encrypted fingerprint feature data obtained from the fingerprint, without storing any data containing the fingerprint image;

4. Every time the fingerprint is used, it will leave the fingerprint trace of the user on the fingerprint collection head, which may be used to copy the fingerprint.

Based on the above comparison, fingerprint identification technology is the most convenient, convenient, non-invasive and cheap biometric technology solution at present, which has great application potential and broad market.