Working Principle of License Plate Recognition Parking Lot System

License plate recognition technology requires that the moving vehicle license plate can be extracted and recognized from the complex background. Through license plate extraction, image preprocessing, feature extraction, license plate character recognition and other technologies, the vehicle brand, color and other information can be recognized. At present, the latest technical level is that the recognition rate of initials and numbers can reach 99.7%, and the recognition rate of Chinese characters can reach 99%.

In parking lot management, license plate recognition technology is also the main means to identify vehicle identity. In the technical requirements for vehicle image and license plate information acquisition and transmission system of parking garage (parking lot) built by Shenzhen Public Security Bureau, license plate recognition technology has become the main means of vehicle identification.

License plate recognition technology is combined with electronic non-stop toll collection system (etc) to identify vehicles. When passing vehicles pass through the crossing, they do not need to stop, that is, they can realize automatic vehicle identification and automatic toll collection. In the parking lot management, in order to improve the traffic efficiency of vehicles at the entrance and exit, license plate recognition is building an unattended fast track for vehicles that do not need to charge parking fees (such as monthly trucks and internal free vehicles), and the access experience of card free and non parking is changing the management mode of access to the parking lot.

Working principle of license plate recognition parking lot system

Nowadays, with the gradual expansion of urban car users, many road intersections or parking lots have adopted intelligent license plate recognition technology, and the most prominent performance is that it is used in parking lots. Now many communities, commercial squares, shopping centers, airports and other major parking lots have been transformed successively, From the previous traditional card swiping parking lot system to the intelligent license plate recognition parking lot system, what are the principles and applications of license plate recognition in the parking lot system? Let's have a look.

1. Vehicle viewing: various methods such as buried coil viewing, infrared viewing, radar viewing technology and gate video viewing can be used to perceive the passing of vehicles and trigger image collection and capture.

2. Image collection: real time and uninterrupted recording and collection of passing vehicles through HD camera capture host.

3. Preprocessing: noise filtering, automatic white balance, automatic exposure, gamma correction, edge enhancement, contrast adjustment, etc.

4. License plate location: scan the army on the gray image after image preprocessing to determine the license plate area.

5. Character cutting: after the license plate area is located in the image, the character area is accurately determined and located through gray-scale gate and binarization, and then the character is cut according to the character scale characteristics.

6. Character recognition: the cut characters are scaled and feature extracted to match with the standard character expression in the character database template.

7. Effect output: output the effect of license plate recognition in text format.

2 Four applications of license plate recognition in parking lot system

1. Entrance and exit of parking lot and community

The application of license plate recognition technology at the entrance and exit of parking lot and community is mainly used to record the license plate number, license plate color and access time of vehicles, and complete the automatic processing of vehicles, so as to save manpower and forward power; For example, when applied to an intelligent community, it can automatically distinguish whether the incoming vehicles belong to the community, and automatically time and charge the gate for Non internal vehicles. In some units, this application can also contact with the vehicle dispatching system to automatically and objectively record the departure of their vehicles.

It is very difficult to manually record the license plate number and parking time of traffic vehicles at the entrance and exit of parking lot and community. Not only will there be errors, but also a lot of manpower needs to be invested. A small license plate recognition equipment can handle many questions at the entrance and exit of the parking lot. It can also be analyzed and identified that the license plate is blocked, paint falling, cracking and blurring, so as to save many troubles for the staff at the parking lot and entrance and exit.

2. Expressway toll station

Now, China's expressway construction is developing rapidly, and the expressway is unobstructed. Each exit is equipped with a toll station, which is convenient for toll collection processing on the one hand, and can also help the traffic police deal with the traffic on the expressway in a standard way on the other hand. The application of license plate recognition technology at the entrance and exit of expressway toll station can greatly facilitate the traffic police to identify the number plate information of illegal trekking vehicles, and effectively deal with and arrest some illegal vehicles.

The toll gate is generally located in the open environment, and some vehicles travel fast, so the request for license plate recognition technology is very high. The traditional license plate recognition is about 160p pixel license plate recognition. The useful image planning is small and the license plate missing rate is high, which can not meet the needs of the times of toll station bayonet. Now the application of high-definition license plate recognition has solved the problem of low license plate recognition rate, which provides a reliable basis for the laws of public security and traffic police.