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Fingerprint Image Enhancement System

IP.com Disclosure Number: IPCOM000080657D
Original Publication Date: 1974-Jan-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Ting, YM: AUTHOR [+2]

Abstract

In automatic fingerprint identification systems, the pattern is captured by a scanner such as a TV camera, which converts the light into an electrical signal. The analog signal is then digitized into levels and then converted into binary signals, for the digital system to perform the pattern recognition. The problem encountered is how to decide whether the signal is either a logic 1 or 0, since there is no reference level to compare with. The lack of such reference level is due to the nature of reproduction of the fingerprint pattern, which is made by transferring a film of ink from the ridge of the finger to the recording medium such as paper (controlling inking uniformity, moisture conditions, and the amount and distribution of the pressure, etc.).

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Fingerprint Image Enhancement System

In automatic fingerprint identification systems, the pattern is captured by a scanner such as a TV camera, which converts the light into an electrical signal. The analog signal is then digitized into levels and then converted into binary signals, for the digital system to perform the pattern recognition. The problem encountered is how to decide whether the signal is either a logic 1 or 0, since there is no reference level to compare with. The lack of such reference level is due to the nature of reproduction of the fingerprint pattern, which is made by transferring a film of ink from the ridge of the finger to the recording medium such as paper (controlling inking uniformity, moisture conditions, and the amount and distribution of the pressure, etc.).

The present logic system provides a reference level for each point on the print. The reference level for each point is obtained by comparing the average of the gray scale value of a square region surrounding the point. The gray scale of the point is then compared with this average value, to decide whether the point should be called at level 1 or 0. The mathematical expression is as follows:.

(Image Omitted)

where g (x,y) is the gray scale of the point P at coordinate (x,y); a (x,y) is the average gray scale value of area with dimension of n x n surrounding the point P; and

(Image Omitted)

The system is illustrated in Fig. 1. Random-access memory 1 has a capacity of b words which are n-bits wide. The value b...