On the line width influence in directional field determination for fingerprint images

Determination of directional field is part of several image processes. In this work, this issue is related with automatic fingerprint identification systems especially in the initial steps. Definition of an accurate and concise model for directional fields improves the performance on estimating the fingerprint ridge and valley orientation. This work presents results of a current research in automatic fingerprint identification system. Text focuses the creation of directional field matrix from fingerprint images. The aim of the process is the location of singular points in fingerprint images with an original technique to smooth the directional image obtained. Experimental tests reveal that the line width is quite relevant in choosing which mask size should be used. Firstly, the system verifies the average width of ridges and valleys in fingerprints to consider whether the process use a mask with 9x9 or 17x17 pixels of size, identifying 8 possible angles for the directional field determination. In spite of the width ridge process evaluation, when creating the directional image, the technique is not time-consuming and tests perform very well both in terms of efficiency and robustness.