A Car Plate Detector using Edge Information

Abstract

This paper describes a new edge-based car plate detection technique to localize and extract car license plates in complex scene. The system works for both moving and stationary vehicles in compressed low resolution video streams obtained from real working environments. To cope with the varied illumination condition, which typically occurs in outdoor environment, the method works on the edge information of the image. We employs vertical Sobel edge detector with automatic variable thresholding. A moving window is then scanned through the edge image. For each location of moving window, we consider the distribution of edge pixels to determine whether it is likely to be a license plate. In the last step, we employ the temporal analysis to suppress false detections. In experiments, we tested our method on several compressed video streams containing 317 moving vehicles in varied illumination conditions from morning to night time. The license plate localization has 94% precision rate