Image Correction Filter for Finger/Palm-print Live Scanner Image

Abstract

We developed a technique that corrects picture quality so that sweat glands on a ridge can be distinguished from the picture obtained by a Finger/Palm-print Live Scanner. The Finger/Palm-print Live Scanner equipment (Live Scanner) has been introduced to the local police stations for fingerprint collection operation. Fingerprint Live Scanner devices have been used as an authentication technology for security systems. The resolution of the Live Scanner image needs to be equal to that of all Live Scanner devices. For example, the required resolution for the police is about 20 points per mm so that sweat glands on a ridge can be distinguished.   We developed a method of image correction to satisfy the requirements for the Live Scanner. Correcting methods for a degraded image such as the inverse filter and the Wiener filter had been proposed. But we are not able to estimate the resolution using the filter designed by these conventional methods. Because these conventional methods use the Signal to Noise ratio as a parameter and don't use relationship to the resolution.   We applied the filter design method that we had developed for a satellite image, to correct the Live Scanner image. The method can evaluate a relationship between the filter effect and the filter parameter by point spread function (PSF). The proposed filter optimization method reduced the full width at half maximum of PSF about 36%, resulting in an improved resolution. With this method, sweat glands on a ridge can be distinguished.