Live scan devices
Fingerprint being scanned
Fingerprint image acquisition is considered the most critical step of an automated fingerprint authentication system, as it determines the final fingerprint image quality, which has drastic effects on the overall system performance. There are different types of fingerprint readers on the market, but the basic idea behind each capture approach is to measure in some way the physical difference between ridges and valleys. All the proposed methods can be grouped in two major families: solid-state fingerprint readers and optical fingerprint readers. The procedure for capturing a fingerprint using a sensor consists of rolling or touching with the finger onto a sensing area, which according to the physical principle in use (capacitive, optical, thermal, acoustic, etc.) captures the difference between valleys and ridges. When a finger touches or rolls onto a surface, the elastic skin deforms. The quantity and direction of the pressure applied by the user, the skin conditions and the projection of an irregular 3D object (the finger) onto a 2D flat plane introduce distortions, noise and inconsistencies in the captured fingerprint image. These problems result in inconsistent, irreproducible and non-uniform contacts[and, during each acquisition, their effects on the same fingerprint results are different and uncontrollable. The representation of the same fingerprint changes every time the finger is placed on the sensor plate, increasing the complexity of the fingerprint matching, impairing the system performance, and consequently limiting the widespread use of this biometric technology.
3D fingerprint
In order to overcome these problems, lately, non-contact (or touchless) 3D fingerprint scanners have been developed. Employing the detailed 3D information, 3D fingerprint scan acquisition provides a digital analogy to this cumbersome analog process of pressing or rolling the finger. By controlling the distance between neighboring points, the resolution is scaled to 500/1000 PPI