Title :
Optical recognition of motor vehicle license plates
Author :
Comelli, Paolo ; Ferragina, Paolo ; Granieri, Michael N. ; Stabile, Flavio
Author_Institution :
Osservatorio Geofisico Sperimentale, Trieste, Italy
fDate :
11/1/1995 12:00:00 AM
Abstract :
A system for the recognition of car license plates is presented. The aim of the system is to read automatically the Italian license number of a car passing through a tollgate. A CCTV camera and a frame grabber card are used to acquire a rear-view image of the vehicle. The recognition process consists of three main phases. First, a segmentation phase locates the license plate within the image. Then, a procedure based upon feature projection estimates some image parameters needed to normalize the license plate characters. Finally, the character recognizer extracts some feature points and uses template matching operators to get a robust solution under multiple acquisition conditions. A test has been done on more than three thousand real images acquired under different weather and illumination conditions, thus obtaining a recognition rate close to 91%
Keywords :
automobiles; closed circuit television; feature extraction; image matching; image segmentation; parameter estimation; video signal processing; Italian license number; TV camera; car license plates; character recognizer; feature projection estimates; frame grabber card; illumination conditions; image parameters; motor vehicle license plates; multiple acquisition condition; optical recognition; rear-view image; recognition process; robust solution; segmentation; template matching operators; weather conditions; Cameras; Character recognition; Feature extraction; Image segmentation; Licenses; Lighting; Parameter estimation; Robustness; Testing; Vehicles;
Journal_Title :
Vehicular Technology, IEEE Transactions on