Real time implementation of a license plate location recognition system based on adaptive morphology

Abstract

License plate recognition (LPR) using morphology has the advantage of higher resistance to changes of brightness, high speed processing, and low complexity. However, these approaches are sensitive to the distance of the plate from the camera and imaging angle. Various assumptions reported in other works might be unrealistic, and cause major problems in practical experiences. In this paper we considered morphological approaches and improved them using adaptive techniques in order to provide more compatibility with practical applications. We examined the developed system on several car plate image databases with different conditions such as different camera distance, and different car views. The average achieved rate of success was 89.95% for all car plate location recognition, which is more than 6.0% improvement in comparison to previous morphological methods. We further developed and implemented an FPGA realization of the pre-processing stage of the system which is the main computation load of our LPR system.