License plate localization using vertical edge map and hough transform based technique

Abstract

Automatic License Plate Recognition (ALPR) system is the growing need by government authorities of different developing countries like India for traffic monitoring and control. The purpose of ALPR system is to track the vehicles violating the speed limit or violating the traffic signal at a road crossing. License plate localization is one of the key modules of any ALPR system. The objective of the current work is to localize the license plate of the vehicle from the vertical edge map of the image using statistical distribution of the vertical edges. Hough transform is then used to tune potential area to its actual dimension. In this work, real time vehicle images are captured from a road-side surveillance camera automatically throughout day and night in an unconstrained outdoor environment. The performance of the technique is tested and it provides 91.23% accuracy when compared with the ground truth data. © 2012 Springer-Verlag GmbH Berlin Heidelberg.