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What Is The Principle Of High-definition License Plate Recognition System Nov 27, 2018

The vehicle number plate is the unique ID card of the vehicle. Its particularity and importance determine that the license plate recognition system becomes an indispensable and important part of the urban intelligent traffic management system. The license plate recognition (LPR) system is an intelligent recognition system based on technologies such as image processing and pattern recognition. The license plate number is recognized by the image of the vehicle traveling on the road taken by the camera.

The process involves: vehicle detection - image acquisition - pre-processing - license plate location - character segmentation - character recognition - result output.


The license plate recognition PTZ camera realizes the capture license plate through light suppression shielding, electronic shutter adjustment, wide dynamic function, etc.


Strong light shielding: Based on the low-light color camera, the brightest part of the image is blocked by the function of the software. In traffic monitoring, the strong light of the headlights can generally be blocked, so that the license plate can be captured more clearly. However, the biggest drawback of this camera is that the software is unclear, and the most bright part of the image is unclear. It is possible to block the license plate number and not be able to handle the capture of high-speed moving objects. At present, domestic cameras have done a lot of glare shielding, and the effects have been mixed.


Adjustable electronic shutter: For high-speed moving objects (the speed of cars on highways is generally above 70KM / hour), you can achieve clear capture by reducing the electronic shutter speed, usually by manual adjustment. However, the biggest problem with this method is that the illumination is different during the day and night. It is necessary to set two shutter speeds to adapt to daytime and nighttime monitoring.


Wide dynamic function: This is the best way to solve the impact of the lights on the capture. The wide dynamic was first proposed by Panasonic. When the background light is too bright, the ordinary camera can not solve the display problem of the light and dark image well.

Vehicle access management

The license plate recognition device is installed at the entrance and exit, the license plate number、 the entry and exit time of the vehicle are recorded and combined with the control devices of the automatic door and the railing machine to realize automatic management of the vehicle. It can be used in the parking lot to realize automatic timing charging. It also can automatically calculate the number of available parking spaces and give tips. The automatic management of parking charges can save manpower and improve efficiency. The application to the intelligent community can automatically determine whether the entering vehicle belongs to the local area, and realize automatic time charging for non-internal vehicles. In some units, this application can also be combined with the vehicle dispatching system to automatically and objectively record the vehicle out of the unit.

The license plate recognition technology in the traffic management system to achieve non-stop and free card collection and improve the efficiency of vehicle access.