Biometrics 简明教程
Physiological Modalities
如前所述，生理模态基于对人体部位的直接测量，例如虹膜、指纹、手指的形状和位置等。
As depicted earlier, the physiological modalities are based on the direct measurement of parts of human body such as iris, fingerprint, shape, and position of fingers, etc.
有些身体特征在人的一生中保持不变。它们可以作为识别个人身份的绝佳资源。
There are some physical traits which remain unaltered throughout a person’s life. They can be an excellent resource for identification of an individual.
Fingerprint Recognition System
它是最为人所知和使用的生物识别解决方案，用于对生物识别系统上的个人进行身份验证。它如此受欢迎的原因是，有十个可用的生物识别源以及易于获取。
It is the most known and used biometrics solution to authenticate people on biometric systems. The reasons for it being so popular are there are ten available sources of biometric and ease of acquisition.
每个人都有一个独特的指纹，由脊、沟和线的方向组成。脊有三种基本图案，即 arch, loop 和 whorl 。指纹的唯一性由这些特征以及分叉和斑点（脊端）之类的 minutiae features 决定。
Every person has a unique fingerprint which is composed of ridges, grooves, and direction of the lines. There are three basic patterns of ridges namely, arch, loop, and whorl. The uniqueness of fingerprint is determined by these features as well as minutiae features such as bifurcation and spots (ridge endings).
指纹是最古老、最流行的识别技术之一。指纹匹配技术有三种类型 −
Fingerprint is one of oldest and most popular recognition technique. Fingerprint matching techniques are of three types −
-
Minutiae Based Techniques − In these minutiae points are found and then mapped to their relative position on finger. There are some difficulties such as if image is of low quality, then it is difficult to find minutiae points correctly. Another difficulty is, it considers local position of ridges and furrows; not global.
-
Correlation Based Method − It uses richer gray scale information. It overcomes problems of minutiae-based method, by being able to work with bad quality data. But it has some of its own problems like localization of points.
-
Pattern Based (Image Based) Matching − Pattern based algorithms compare the basic fingerprint patterns (arch, whorl, and loop) between a stored template and a candidate fingerprint.
Merits of Finger Recognition System
-
It is the most contemporary method.
-
It is most economical method.
-
It is highly reliable and secure.
-
It works on a small template size, which speeds up the verifying process.
-
It consumes less memory space.
Facial Recognition System
面部识别基于确定下巴、下颌、眼睛、眉毛、鼻子、嘴唇和颧骨的形状和大小。2D 面部扫描仪开始读取面部几何形状并将其记录在网格上。面部几何形状以点的形式传输到数据库中。比较算法执行面部分割并得出结果。面部识别以以下方式执行：
Facial recognition is based on determining shape and size of jaw, chin, shape and location of the eyes, eyebrows, nose, lips, and cheekbones. 2D facial scanners start reading face geometry and recording it on the grid. The facial geometry is transferred to the database in terms of points. The comparison algorithms perform face matching and come up with the results. Facial recognition is performed in the following ways −
-
Facial Metrics − In this type, the distances between pupils or from nose to lip or chin are measured.
-
Eigen faces − It is the process of analyzing the overall face image as a weighted combination of a number of faces.
-
Skin Texture Analysis − The unique lines, patterns, and spots apparent in a person’s skin are located.
Merits of Facial Recognition System
-
It offers easy storage of templates in database.
-
It reduces the statistic complexities to recognize face image.
-
It involves no physical contact with the system.
Iris Recognition System
虹膜识别基于人眼中的虹膜模式。虹膜是一种有色弹性组织，中心有可调节的环形开口。它控制瞳孔的直径。在成年人中，虹膜的纹理在其整个生命周期中都是稳定的。左眼和右眼的虹膜图案不同。虹膜图案和颜色因人而异。
Iris recognition works on the basis of iris pattern in human eye. The iris is the pigmented elastic tissue that has adjustable circular opening in center. It controls the diameter of pupil. In adult humans, the texture of iris is stable throughout their lives. The iris patterns of left and right eyes are different. The iris patterns and colors change from person to person.
它涉及用一枚合格的相机拍摄虹膜图片，存储它，并使用数学算法将它与候选人的眼睛进行比较。
It involves taking the picture of iris with a capable camera, storing it, and comparing the same with the candidate eyes using mathematical algorithms.
Merits of Iris Recognition System
-
It is highly accurate as the chance of matching two irises is 1 in 10 billion people.
-
It is highly scalable as the iris pattern remains same throughout a person’s lifetime.
-
The candidate need not remove glasses or contact lenses; they do not hamper the accuracy of the system.
-
It involves no physical contact with the system.
-
It provides instant verification (2 to 5 seconds) because of its small template size.
Hand Geometry Recognition System
它包括测量手掌的长度和宽度、表面积、手指的长度和位置以及手的整体骨骼结构。每个人的手都是独一无二的，并且可以用来辨别其他人。手掌几何系统有两种−
It includes measuring length and width of palm, surface area, length and position of fingers, and overall bone structure of the hand. A person’s hand is unique and can be used to identify a person from others. There are two Hand Geometry systems −
-
Contact Based − a hand is placed on a scanner’s surface. This placement is positioned by five pins, which guide the candidate hand to position correctly for the camera.
-
Contact Less − In this approach neither pins nor platform are required for hand image acquisition.
Merits of Hand Geometry Recognition System
-
It is sturdy and user friendly.
-
The changes in skin moisture or texture do not affect the result.
Retinal Scanning System
视网膜是眼球后部的内衬层，覆盖了眼球内表面的 65%。它包含 photosensitive 细胞。由于供应血液的血管网络复杂，每个人的视网膜都是独一无二的。
Retina is the lining layer at the back of the eyeball that covers 65% of the eyeball’s inner surface. It contains photosensitive cells. Each person’s retina is unique due to the complex network of blood vessels that supply blood.
它是一种可靠的生物特征，因为视网膜图案在人的一生中保持不变，除了患有糖尿病、青光眼或某些退行性疾病的人的图案除外。
It is a reliable biometric as the retina pattern remains unchanged throughout the person’s life, barring the patterns of persons having diabetes, glaucoma, or some degenerative disorders.
在视网膜扫描过程中，要求一个人取下隐形眼镜或眼镜。将低强度的红外光束投射到某人的眼睛中 10 至 15 秒。红外光被血管吸收，在扫描过程中形成血管图案。然后将此图案数字化并存储在数据库中。
In retinal scanning process, a person is asked to remove lenses or eyeglasses. A low-intensity infrared light beam is casted into a person’s eye for 10 to 15 seconds. This infrared light is absorbed by the blood vessels forming a pattern of blood vessels during the scan. This pattern is then digitized and stored in the database.
Merits of Retinal Scanning System
-
It cannot be forged.
-
It is highly reliable as the error rate is 1 out of a crore samples (which is almost 0%).
Demerits of Retinal Scanning System
-
It is not very user friendly as the user needs to maintain steadiness that can cause discomfort.
-
It tends to reveal some poor health conditions such as hypertension or diabetes, which causes privacy issues.
-
Accuracy of the results is prone to diseases such as cataracts, glaucoma, diabetes, etc.
DNA Recognition System
*D*eoxyribo *N*ucleic *A*cid (DNA) 是人类中的遗传物质。除了同卵双胞胎，每个人都通过其 DNA 中的特征进行唯一识别，该特征位于细胞核中。有多种来源可以收集 DNA 模式，例如血液、唾液、指甲、头发等。
*D*eoxyribo *N*euclic *A*cid (DNA) is the genetic material found in humans. Every human barring identical twins, is uniquely identifiable by the traits found in their DNA, which is located in the nucleus of the cell. There are number of sources from which DNA patterns can be collected such as blood, saliva, nails, hair, etc.
在细胞内，DNA 以称为 chromosomes 的长双螺旋结构组织。人类中有 23 对染色体。在 46 条染色体总数中，后代从每个亲生父母那里继承 23 条染色体。后代的 99.7% DNA 与父母的共享。剩余的 0.3% DNA 包含了个体特有的重复编码。
Within cells, DNA is organized in long double helix structure called chromosomes. There are 23 pairs of chromosomes in humans. Out of the 46 total chromosomes, the offspring inherits 23 chromosomes from each biological parent. 99.7% of an offspring’s DNA is shared with their parents. The remaining 0.3% DNA contains repetitive coding unique to an individual.
DNA 分析的基本步骤为：
The fundamental steps of DNA profiling are −
-
1. Separating the DNA from sample acquired from either of blood, saliva, hair, semen, or tissue.
-
2. Separating the DNA sample into shorter segments.
-
3. Organizing the DNA segments according to size.
-
4. Comparing the DNA segments from various samples.
样本越详细，比较就越精确，进而越能识别出该个体。
The more detailed the sample is, the more precise the comparison and in turn the identification of the individual is.
DNA 生物识别在以下方面与其他所有生物识别技术有所不同：
DNA Biometrics differs from all others in the following ways −
-
It needs a tangible physical sample instead of image.
-
DNA matching is done on physical samples. There is no feature extraction or template saving.