Khosro Kamalatabar Malekshah - Department of Computer Engineering, Islamic Azad University, Sari Branch, Sari, Iran
Hossein Numatzadeh - Department of Computer Engineering, Islamic Azad University, Sari Branch, Sari, Iran
Homayun Motameni - Department of Computer Engineering, Islamic Azad University, Sari Branch, Sari, Iran

The license plate edge detection is the most important step of the process of plate identification. Plate recognition system is an automated system that captures vehicle location, vehicle license plate accurately on various vehicles at different times of day and night sets. In this paper the issue of searching the exact location of the license plate from the input images using Sobel operator for edge detection and image processing and histogram analyzing techniques for candidate areas restriction has been examined.The proposed method is tested on the database containing 250 different input images with different background, size and angles in different lighting condition and during different times of the day on different kinds of vehicles (cars, vans and trucks and etc). And the rate of the correct extraction of the exact location of the license plate was 88.4% .The response time and the processing speed of the proposed method is faster in Comparewith existing works.

Image Processing, License Plate, Sobel Operator, Histogram Analysis