Fingerprint characteristics

- Dec 08, 2017-

Fingerprinting refers to the smooth texture pattern of the finger's surface consisting of alternating "ridges" and valles that are formed with strong randomness depending on the initial environment in which the epidermal portion of the finger is formed in the embryo. The characteristics of a fingerprint are used to distinguish different fingerprints from the others. Endpoints and bifurcation points are the most commonly used features. In the algorithm is to record their location and direction, the center point and the triangular point in criminal investigation system commonly used, but not commonly used in civilian systems. Because the collectors used in these applications tend to be small in area, it is harder to fully capture the center and delta points. Crosses and islets are often not practical in real systems due to computer problems. It has been proposed to use sweat gland hole for fingerprinting, but this method requires fingerprinting equipment to have a very high resolution, it is not used in the actual system.

Fingerprint collector, fingerprint capture devices commonly used in three, optical, silicon chip, ultrasonic. Among them, the optical fingerprint reader is the earliest fingerprint collector, is the most commonly used, but also appeared with the grating lens replacement prism and lens system collector. Some photoelectric conversion CCD devices have been replaced by CMOS imaging devices, thus omitting the image acquisition card directly to digital images.

Optical fingerprint collector with a long time; temperature and other environmental factors, strong adaptability; high resolution advantages. However, due to the optical path, undistorted collector size larger. Usually have more serious optical distortion; acquisition window surface often traces of legacy phenomenon. CCD device may be due to aging of life, reduce the image quality and other defects.