Traffic monitoring in motorways by real-time number plate recognition

The problem of traffic monitoring in motorways by the number plate recognition of all moving vehicles is addressed. The proposed system is composed of local processing units positioned near the motorway accesses, connected by radio link to a central control station. In the local units we process each frame of the video sequence in order to extract character information and to merge them in a temporal post-processing step. This ensures that most of recognition errors may be recovered during the permanence of the vehicle inside the camera field of view. Moreover, there is no need for an external device to trigger image acquisition, because the whole video sequence is processed. If the recognized number plate is contained into a predefined list, an alarm signal is generated. All number plates are locally stored for further search operations by the authorities. The central control station gathers alarms from the connected processing units and is responsible for the updating and the broadcasting of the list of number plates to be searched.