License plate detection using mathematical morphology

This Automatic license plate recognition (LPR) is an important technique in the intelligent transport system. It has been widely adopted into numerous applications such as unattended parking, security control and stolen vehicle verification. In general, LPR systems consist of two separate modules: Plate detection and characters recognition. Several methods have been proposed for the detection of license plates based on: Discrete Wavelet Transform, Hough transform, neural networks and others. In this paper, we describe a method of license plate detection using mathematical morphology.

I. Introduction

License Plate Recognition (LPR) is an important research area that has been widely studied in the last two decades. This technology is gaining popularity in security and traffic installations. The technology concept assumes that all vehicles already have the identity displayed (the plate). The system uses illumination (such as Infra-red) and a camera to take the image of the front or rear of the vehicle, then an image-processing software analyzes the images and extracts the plate information. This data is used for enforcement, data collection etc. The LPR system significant advantage is that the system can keep an image record of the vehicle which is useful in order to fight crime and fraud. Additionally, this technology does not need any installation per car (such as in all the other technologies that require a transmitter added on each car or carried by the driver).