Parallelogram and Histogram based Vehicle License Plate Detection

This paper describes a new approach to analyze road images which often contain vehicles and extract license plate (LP) from natural properties by finding vertical and horizontal edges from vehicle region. The proposed technique consists of three main modules: (a) segmentation technique named as sliding concentric windows (SCW) on the basis of a novel adaptive image for detecting candidate region, (b) refining by using HSI color model on the basis of using hue and intensity in HSI color model verifying green and yellow LP and white LP, respectively and (c) finally, verify and detect VLP region which contains predetermined LP alphanumeric character by using position histogram. In the proposed method, input vehicle images are converted into gray images. After then the candidate regions are found by sliding concentric windows. We detect vehicle license plates (VLP) region which contains predetermined LP color by using HSI color model and LP alphanumeric character by using position histogram. Experimental results show that the proposed method is very effective in coping with different conditions such as poor illumination and varied weather. Experimental results also show that the distance from the vehicle varied according to the camera setup.