Human skin consists of three parts: the epidermis, the dermis, and the subcutaneous tissue. Fingerprints are the lines that protrude from the epidermis. Due to the genetic characteristics of people. Although fingerprints are common to all people, they are different. Stretch out your hand, look carefully, you can find a small fingerprints are divided into several types: concentric circles or spiral lines, looks like a whirlpool in the water, called bucket-shaped lines; some lines are open on one side, like a dustpan, called the skip-shaped lines; there are lines like a bow, called the bow line pattern. In addition to the different shapes of fingerprints, the number and length of the lines are also different. It is said that among the more than five billion people in the world, no two fingerprints have been found to be exactly the same. What is more interesting is that fingerprints begin to appear in the third or fourth month of a fetus, and are formed at about six months of age. As the baby grows into an adult, the fingerprint only grows larger and thicker, but its shape and features remain fixed.

Editing Basic Types of Fingerprints

There are three basic types of fingerprints - bucket, bow and skip. It is the difference in the direction of subcutaneous tissue top pressure on the epidermis of the finger belly that creates these different types. Studies have shown that if someone's finger belly is high and round, the pattern of their fingerprints will be spiral. Now, scientists have been able to reproduce those more common fingerprints through modeling, as well as duplicate the formation of less complex and rare fingerprints.

Fingerprints are lines formed by the bumpy skin on the ends of human fingers. Fingerprints increase friction when the hand touches an object, making it easier to exert force and grip the object. They are a natural part of the evolutionary process of human beings. The first type of fingerprints is the obvious ones, which are visible to the eye. If the hand is dipped in paint, blood, ink and other items transferred from the fingerprints are usually printed on the fingerprint card to become the basic information;

The second category is the molding pattern, which refers to the fingerprints in the soft material, such as hand contact embossed on the candles, clay found on the fingerprints;

The third category is the latent fingerprints, this type of fingerprints is the body's natural secretions such as sweat, the fingerprints transferred to form the pattern, not easy to visually find, is the most common in the crime scene, the fingerprints are the most common in the case. The most common fingerprints in the crime scene. Latent fingerprints are often the first finger contact with grease, sweat or dust, and then contact with a clean surface and left, although the naked eye can not see these fingerprints, but after a special method and the use of some special chemical reagents to deal with, that is, it can show these latent fingerprints. The fingerprints most commonly encountered by forensic personnel are latent prints. If the fingerprints are left on the surface of non-absorbent objects such as metal, plastic, glass, tiles, etc., the test method is easier. Usually, the powder method can be used, choosing a powder with a large color contrast and sprinkling it on the surface of the item to extract the complete fingerprints; another method is the magnetic powder method, using micro-fine particles of iron powder, using a magnet as a brush, brushing and sweeping back and forth to reveal the fingerprints. If the fingerprints remain on the surface of paper, card, leather, wood and other absorbent items, they must be chemically processed to be visible in the laboratory.

Commonly used chemical methods are: iodine fumigation - that is, the use of iodine crystals heated to produce a vapor, which reacts with the fingerprint residue grease, there will be a yellowish-brown fingerprints, which must be immediately photographed or chemically fixed;

Ninhydrin (Ninhydrin) method -- Spraying the reagent on the test body and reacting with the amino acids in the body secretions, a purple fingerprint will appear;

The silver nitrate method -- Silver nitrate solution reacts with the ammonia sodium in the latent fingerprints and produces a black fingerprint in sunlight;

The silver nitrate method is a method of fingerprinting. fingerprints;

Fluorescent reagent method - fluorescent ammonia and phthalaldehyde almost immediately with the fingerprint residue of protein or amino acids, resulting in a highly fluorescent fingerprints, this reagent can be used on the surface of colored items.

Other methods can be used to collect evidence, such as the triple-second adhesive method, which uses a gas of cyanoacrylate to react with water and amino acid molecules to produce fingerprints

Edit Fingerprints are unique

Fingerprints are unique features of the human body, and they are complex enough to provide sufficient characteristics for identification purposes.

Fingerprints are lines formed by the bumpy skin on the end digits of human fingers. Fingerprints increase friction when the hand touches an object, making it easier to exert force and grip the object. They are a natural part of the evolutionary process of human beings. No different people have been found to have the same fingerprints, so each person's fingerprints are unique. Since fingerprints are unique to each individual, in recent centuries, fingerprints left by criminals at the scene of a crime have become important clues for the police to track down suspects. Today's fingerprint identification methods are computerized, making the identification process faster and more accurate.

Fingerprints are genetically influenced, and because everyone's genes are different, so are their fingerprints. However, although the formation of fingerprints is mainly influenced by heredity, there are also environmental factors. When the fetus develops in the mother's body for three to four months, fingerprints are already formed, but children's fingerprints will change slightly during the growth period, and they will not be finalized until puberty when they are about 14 years old. In the process of skin development, although the epidermis, dermis, as well as the stroma layer are *** with the growth, but the soft subcutaneous tissue grows faster than the relatively hard epidermis, and therefore will produce a steady stream of upward pressure on the epidermis, forcing the epidermis grows slower to the inner layers of the tissue contraction and collapse, and gradually become curved wrinkled, in order to alleviate the pressure exerted by subcutaneous tissue to it. In this way, on the one hand, force to attack upward, on the one hand, forced to withdraw downward, resulting in the epidermis grows curved, pitted, forming lines. This process of bending and wrinkling fluctuates and undulates with changes in the upper pressure exerted by the inner tissues, forming uneven ridges or folds until the developmental process is discontinued, and the fingerprints are finally finalized to the point of death. Some people say that fingerprints change after a bone marrow transplant, and that is not true. Fingerprints don't change unless they are implanted or damaged deep into the basal layer.

Edit Fingerprint Uses

Don't underestimate your fingerprints, they can be very useful! Fingerprints from the skin of many small particles arranged in the composition of these small particles feel very keen, as long as the hand touch objects, will immediately feel the cold, hot, soft, hard and other kinds of "intelligence" notification pick up the brain of this command, and then, the brain according to these "intelligence", give orders! Then, the brain according to these "intelligence", give orders, command action. Fingerprints also have to enhance the role of skin friction, so that the fingers can hold things tightly, not easy to slip off. We usually draw, write, take the tool, do handmade, so you can be so handy, easy to use, which has the fingerprints of the credit.

Because of these characteristics of the fingerprints, it has long attracted people's interest. In ancient times, people took the fingerprints as a "seal", printed on the official documents.

It is said that more than a hundred years ago, the police began to use fingerprints to solve crimes.

Now, with the development of science and technology, fingerprints have a new use in medicine. Some doctors have found that by examining people's fingerprints and palm prints, they are able to detect certain diseases.

In recent years, fingerprints and computers have become good friends.

At present, many businesses are also using the unique characteristics of fingerprints, developed some high-tech equipment to reflect the fingerprints to the life of the convenience and security, such as: fingerprint locks, fingerprint access control, fingerprint time and attendance machine, fingerprint collector, fingerprint safes, and fingerprint network login technology and so on, according to the survey of the domestic high-grade intelligent neighborhoods are equipped with fingerprint locks, fingerprint access, fingerprints have been used in the equipment. The earliest is the fingerprint time and attendance machine, the company personnel managers in order to put an end to the substitute punch card, have adopted fingerprint time and attendance machine. At the same time, China's first network fingerprint login technology provider has launched a beta version, is expected to solve the problem of network account security.

What are the new uses for a small fingerprint in the future? The new labyrinth is in front of us, waiting for us to explore, to seek.

Editing this section of the fingerprints to solve the case

Fingerprints, also known as handprints, there is a broad and narrow sense of the difference. Fingerprints in the narrow sense refers to the first section of a person's fingers on the palm surface of the skin of the papillary line pattern; broad fingerprints include fingerprints, knuckleprints and palmprints. Fingerprints and fingerprints in the literal difference, that is, fingerprints refers to the first section of the finger on the palm surface of the skin of the papillary line pattern, fingerprints is this papillary line pattern left behind the marks, but in judicial practice, the convention, fingerprints and fingerprints concept is common.

Leaving marks is mainly due to the human fingers, palm surface of the skin, the presence of a large number of sweat glands and sebaceous glands (think of your nervousness or excitement when the sweat in the heart of the hand), as long as the existence of life activities, there is a constant sweat, sebaceous fluid discharge, a little bit like an atomic seal constantly ink seepage to the surface of the seal, so as long as the fingers, the palm of the hand in contact with the surface of the object, it will be like an atomic seal as automatic. Leaving a mark. Of course, this is mainly because fingers and palms themselves can leave fingerprints. If your fingers and palms are covered with other liquid substances, such as oil from your head and face (which is what you most often use for "ink cartridges"), blood, and fingerprint ink, the principle of fingerprinting will be more like an ordinary seal.

Fingerprint forensics, including fingerprint search and discovery. Fingerprint search scope: (1) the center of criminal activity; (2) the scene of the import and export and its surrounding; (3) criminals may have touched the goods; (4) criminals left at the scene of a variety of weapons and objects.

Fingerprints found methods: (1) haze observation method: to smooth the surface of the object haze observation; (2) naked eye observation method: with the help of a certain light, angle of observation. (3) magnifying glass observation method: with the help of a magnifying glass in a certain light, angle observation; (4) ultraviolet observation method: with the help of ultraviolet characteristics of observation; (5) physical and chemical observation method: for the potential handprints with the naked eye is difficult to observe the discovery of physical and chemical processing, need to rely on the physical and chemical processing, in order to look for the discovery.

People suffering from special diseases in the scene to leave "special fingerprints" of the situation, mainly in some of the diseases that can make the patient's sweat changes. Like diabetes, due to the patient's sweat in the sugar increase, if a lot of sweat fingerprints, there may be like some novels or puzzles described in the phenomenon of ants, bees gathered. There is also like a while ago on TV, someone long-term use of low-quality porcelain tea cups to drink tea, resulting in copper poisoning, the result of the phenomenon of red sweat. Like this patient, if you leave fingerprints, you will find that the fingerprints are red.

In Argentina, fingerprint evidence was used to make a woman who killed her two children confessed to the crime, which is the first time that modern fingerprinting technology has been adopted by the court.

Editing the Principles of Fingerprint Identification Technology

Fingerprint identification technology involves four main functions: reading fingerprint images, extracting features, saving data, and comparing. In the beginning, the image of human fingerprints is read by fingerprint reading equipment, and after the fingerprint image is taken, the original image is processed initially to make it clearer. Next, the fingerprint recognition software establishes a digital representation of the fingerprint - feature data, a unidirectional conversion that can be converted from fingerprint to feature data but not from feature data to fingerprint, and two different fingerprints will not produce the same feature data.

Some algorithms produce more data by combining node and orientation information that indicates the relationship between individual nodes, and some algorithms also process the entire fingerprint image. In any case, these data, often called templates, are saved as 1K-sized records. Regardless of how they are composed, there is still no standard for templates or a published abstraction algorithm, but rather individual vendors take matters into their own hands. Finally, the templates of two fingerprints are compared by a computerized fuzzy comparison method to calculate their degree of similarity, and ultimately the result of matching two fingerprints is obtained. Fingerprints are actually more complex.

Unlike manual processing, many biometrics companies do not directly store images of fingerprints. Many digitization algorithms have been generated over the years at various companies and their research institutes (in the United States, the law considers fingerprint images to be private and therefore cannot be stored directly).

But fingerprint recognition algorithms ultimately boil down to finding and comparing fingerprint features on a fingerprint image. Fingerprint featuresWe define two categories of fingerprint features for fingerprint verification: overall features and local features. General features are those that can be directly observed with the human eye and include: the basic pattern of loops, arches, and whorls. All other fingerprint patterns are based on these three basic patterns. It is not enough to rely only on the pattern type to distinguish fingerprints, this is only a rough categorization, but the categorization makes it easier to search for fingerprints in large databases.

PatternArea is the area of the fingerprint that contains the general features, i.e., from the pattern area, it is possible to distinguish which type the fingerprint belongs to. Some fingerprint recognition algorithms only use data from the pattern area, and Aetex's fingerprint recognition algorithm analyzes and identifies fingerprints using the complete fingerprint obtained, not just the pattern area.

The CorePoint is located at the progressive center of the fingerprint pattern and is used as a reference point for reading and comparing fingerprints.

The Delta point is located at the first bifurcation or break in the fingerprint from the CorePoint, or at the point where two lines converge, isolate, turn, or point to these singularities. The delta point provides the starting point for counting and tracking fingerprint lines.

TypeLines TypeLines are cross-hatched lines that appear where the lines that surround the pattern area begin to run parallel to each other. TypeLines are usually very short and break off, but their outer lines begin to run continuously.

RidgeCount refers to the number of fingerprint ridges in the pattern area. When calculating the ridge count of a fingerprint, it is usually first in the connection between the core point and the triangular point, and the number of intersections of this line with the fingerprint lines can be considered as the ridge count of the fingerprint. Localized featuresLocalized features are the nodes on a fingerprint. Two fingerprints will often have the same general characteristics, but their local characteristics, the nodes, may not be identical MinutiaPoints Fingerprint lines are not continuous, smooth and straight, but often have breaks, bifurcations or folds. These breaks, bifurcations and turns are called "nodes". It is these nodes that provide confirmation of the uniqueness of the fingerprint. There are four different characteristics of nodes on a fingerprint:

1. Classification - There are several types of nodes, the most typical being endings and bifurcations

A. Ending - where a fingerprint ends.

B. Bifurcation - where one grain splits into two or more.

C. RidgeDivergence - two parallel ribs separate here.

D. Isolation (DotorIsland) - a particularly short line to become a point

E. Enclosure (Enclosure) - a line separated into two, immediately after the merger of a small ring so that the formation of a small ring is called a ring point

F. ShortRidge - one end of the ShortRidge - one end, but not so short as to become a point of the grain,

2. Orientation - nodes can be oriented in a certain direction.

3. Curvature - describes how quickly the direction of the stripe changes.

4. Position - the position of a node is described by (x,y) coordinates, either absolute or relative to a triangulation point or feature point.