Automatic License Plate Recognition
By: Shenzhen TGW Technology Co., Ltd



According to the survey, automatic license plate recognition technology in parking lot is more and more popular with car owners and parking lot operators. Its highly efficient intelligent function can enable vehicles to pass quickly, avoid road congestion and user queuing in peak periods. With the license plate number as the entry and exit vouchers, improve the safety of vehicle parking, solve the loopholes in charging;Eliminate card management and eliminate the problem of users forgetting to bring CARDS. So with so many features, what are the components of a car parking license plate recognition system?

Vehicle automatic license plate recognition system is the same as the original parking system in basic equipment composition, such as the two system are both equips with intelligent road brake, road brake control machine (ticket box), ground sensor coil, vehicle detector, electronic display screen, sentry box, monitoring camera, parking management computer composition. The biggest difference is that automatic license plate recognition has many advantages, such as video identification, No-stop pass, which requires the parking lot surveillance cameras, road brake control machine has a higher functional requirement. Let's learn more about the important equipment of alpr system.

1. Surveillance cameras, there is a big difference between surveillance cameras and general image contrast of the parking lot, Surveillance cameras is a special camera of theautomatic license plate recognition, using high-speed DSP embedded intelligent hardware, embedded software, video acquisition, image preprocessing, license plate detection, license plate segmentation, character recognition, tracking, contrast, image compression and data transmission of complex computer image processing technology, system identification speed, high reliability, equipment can be imported to two-way video for license plate recognition, respectively, according to the different application scenarios, two-way video can customize for the front or the rear of the pattern recognition, They don't affect each other.

2. Supplementary light lamp, license plate recognition has very high requirements on the on-site environment of the parking lot, and it is inevitable that there will be insufficient light. Supplementary light lamp can well ensure that the license plate recognition camera has enough light to successfully capture the license plate.

Learn more about our ALPR solution.

ANPRWhat is ANPR?by:Shenzhen TGW Technology Co.,Ltd
Automatic number Plate Recognition (ALPR) is a technology that can detect the Vehicle on the monitored road and automatically extract Vehicle License Plate information (English letters, Arabic Numbers and Plate color) for processing. License plate recognition is one of the most important parts of modern intelligent transportation system. Based on digital image processing, pattern recognition, computer vision and other technologies, it analyzes the vehicle images or video sequence taken by the Anpr camera to obtain the unique license plate number of each vehicle, thus completing the recognition process. Parking fee management, traffic flow control index measurement, vehicle positioning, car theft, automatic superhighway overspeed supervision, red light electronic police, highway toll station and other functions can be realized Because of a serious of follow-up processing . It is important for maintain traffic safety, fighting crime,prevent traffic jam and realize traffic automation management.


Common application scenarios of ANPR1.ANPR in fighting crime    In fact, we can pinpoint the culprit of many traffic violations or other crimes by tracing to the license plate. Many intersections are equipped with a red light violation detection system, and the most important part of this system is intelligent number plate recognition system modules, the system record the number plate of vehicle , and then analysis which are suspicious vehicles according to Database comparison, determine illegal information, thus reducing the illegal behavior, control the status of the traffic on the road to ensure safety.Countries around the world are actively using ANPR to combat crime.
On April 24， 2015,it was announced that Victoria Police to consider implementing $86 million live video ANPR system for patrol cars

in November 2014, it was announced that The Royal Malaysian Police (PDRM) was to employ an Automated Number Plate Recognition
(ANPR) system to identify vehicles with foreign registration plates with unsettled summonses

On December 20, 2018， the local authority of Redbridge Announced that  £1.5m ANPR cameras installed to fight crime.

Automatic number plate recognition software is proving invaluable to the Huntly police force.Within four hours of using the ANPR 
equipment last week, the team of eight stopped over 25 vehicles, including a car which had been stolen by knifepoint in Northland.

2.anpr in parking lot management 
    Nowadays, more and more parking lots have improved access to ANPR to improve management efficiency. The traditional parking system cannot meet people's needs because of the high labor cost and low management efficiency. The parking lot managers are planing to update the traditional parking systems into smart parking systems 
 
    The traditional parking system can be modified by the automatic number plate recognition (anpr) technology. The ANPR camera captures the vehicle information and the image of the person clearly, so that the owner can enter and exit the parking lot without stopping. It can also monitor the running status of all online devices, realize equipment fault pre-discovery, self-repair, query various report functions in real time, and provide customers with on-site information in the form of multiple pictures, with real-time query charge amount, the system breaks through the region. Sexual restrictions have enabled remote management across the country. The parking lot charging system is charged automatically and supports the current popular mobile payment or login to a special parking app for payment. The whole process is fast and convenient.


       At present, the traditional parking lot management system is prone to cause congestion during the peak hours of commuting. The traffic efficiency is extremely low because of the simple function of the system. Traditional parking lot does not have the functions of helping the owner to find a parking space, finding a car and paying a fee quickly. Manual charging also leads to capital loopholes, makes difficulty in collecting money for change, etc. it is necessary to install a separate database and front-end display for the parking lot during installation. The ANPR system adopts a fully automatic computer management mode. From the exit of the parking lot to the gate and then to the management center, all of them are maneged by the automatic control computer to make it convenient to manage. ANPR decrease the time we spend on vehicle entering the parking lot and leaving the parking lot. And it can easily realize unmanned operation at the entrance and exit, and automatically charge, which can greatly save costs. Therefore, the intelligent parking system that can meet the needs of the management and the owners has very high potential, and the future development prospect is very broad.


Sorts of ANPR SYATEM    The basic hardware configuration of a license plate recognition system is composed of A ANPR camera, master controller, acquisition card and lighting device. The software is composed of an image analysis and processing software with license plate recognition function and a background management software to meet specific application requirements.
License plate recognition system has two sorts of products, one is a combination of hardware and software, or the realization of hardware recognition function module, forming a full hardware license plate recognition, such as DSP. Another sort is open software and hardware system, that is, hardware adopts standard industrial products, software as embedded software. Both the two product formats have advantages as well as disadvantages. The advantage of the open system is that the hardware adopts standard industrial products, and the operation and maintenance are easy to grasp. The purchase of spare parts can be obtained from any manufacturer, and there is no need to worry about the permanent failure of products or procurement difficulties due to the failure or shortage of supply of one manufacturer. The integrated hardware and software products make it easier for users to operate and control the products. For later maintenance debugging is also easier to grasp.


Anpr working process    Automatic number plate recognition is a pattern recognition technology that USES dynamic video or static images of vehicles to automatically recognize license number and license color. Its hardware base generally includes trigger equipment (monitoring whether the vehicle enters the field of vision), camera equipment, lighting equipment, image acquisition equipment, processor (such as a computer) that recognizes the license plate number, etc. Its software core includes license plate positioning algorithm, license plate character segmentation algorithm and optical character recognition algorithm. Some ANPR systems also have the ability to determine whether there is a car by using the video vehicle detection techno. A complete license plate recognition working process(as shown in figure ) should be include of vehicle detection, image acquisition, license plate recognition and other parts . When the vehicle detection part detects the arrival of a vehicle, the image acquisition unit is triggered to collect the current video image. The license plate recognition unit processes the image, locates the license plate position, then separates the characters in the license plate for recognition, and then output the license plate number.

ANPR system Technical indicators    There are three indexes to evaluate a number plate recognition system: recognition rate, recognition speed and background management system. Of course, the premise is that the system should be able to operate reliably.
1.ANPR Recognition rate    Whether a ANPR system is practical or not, the most important index is the recognition rate. The international traffic technology has made the special identification rate index elaboration, the request is 24 hours all-weather brand accurate identification rate above 95%.
In order to test the recognition rate of a number plate recognition system, it is necessary to install the system in a practical application environment, operate 24 hours a day or more, collect license plates of at least 1000 natural traffic flows for identification, and store license plate images and recognition results for retrieval and viewing. Then, it is necessary to get the image of the actual passing vehicle and the correct result of manual identification. Then the following recognition rate can be calculated:
1. The identification rate of natural traffic flow = the total number of correct identification of the full plate/the total number of actual passing vehicles
2. The percentage of identifiable license plates = the total number of license plates correctly read by human/the total number of vehicles actually passed
3. The correct recognition rate of all plates = the total number of license plates correctly recognized by all plates/the total number of license plates manually read. These three indicators determine the recognition rate of license plate recognition system.
2.ANPR  Recognition speed    Recognition speed determines whether a license plate recognition system can meet the requirements of real - time application. A system with a high recognition rate, if it takes a few seconds or even minutes to recognize the result, will not be practical because it cannot meet the real-time requirements in practical applications. For example, speed is a powerful way to reduce travel time and avoid lane congestion in an application that USES license plate recognition to reduce travel time.
The speed of identification proposed by international traffic technology is less than 1 second, the faster the better.
3.ANPR Background management    The background management system of a license plate recognition system determines whether the license plate recognition system is useful. It is important to keep in mind that it is impossible to achieve a 100% recognition rate because the license plate is defaced, obscured, obscured, or the weather may be bad (snow, hail, fog, etc.). The functions of the backend management system should include:
    1. Reliable storage of identification results and vehicle image data, which can protect image data from loss when the multi-function system operation makes the network error-prone, and facilitate manual investigation afterwards;
    2, effective automatic alignment and query technology, the recognized license plate number with the database of thousands of license plate number automatic alignment and alarm prompt, if the license plate number is not read correctly when the use of fuzzy query technology to obtain the relative "best" comparison results;
    3, a good license plate recognition system for network operation, but also need to provide real-time communication, network security, remote maintenance, dynamic data exchange, automatic database update, hardware parameter Settings, system fault diagnosis.
 
 
How to choose ANPR provider1.Attaches great importance to stability
    With the improvement of product algorithm and industry technology, integration is not an important topic for a long time, but the most important point at the present stage is "stability". Stability is defined as: within a given speed range, the accuracy must be achieved without excessive error due to external environmental influences.
For example, a license plate system that is more than 90 percent accurate during the day, down to 80 percent in the evening and 70 percent at night is more difficult to integrate than a license plate recognition system that is on average 70 percent accurate throughout the day. Because the user might think, now that the recognition rate of 90% during the day, the all-weather only reasonable accuracy is 90%, this specification does not include strange environment interference (torrential rain, hail, fog, sections, etc.), and set up the environment limit (, big wind shake height limit restrictions, it is not easy to artificial damage, etc.).
 
2.Product testing
    Almost every company claims to have high recognition rate, but in order to avoid later because both sides cognitive difference of product, and to each other, the responsibility of dysfunctional users in purchasing the license plate recognition system, as well as for product testing, and test had better more than two weeks time, compare results can determine whether "exaggerated". Because of the changeable environment, two weeks should be able to grasp about 80% of the conditions that may affect the identification rate of the field. If you only measure it for a day or even a few hours, you cannot understand it.
 
    In addition, since license plate recognition is a "system", the hardware and software architecture will certainly affect the "present results". As to what kind of software and hardware are suitable for what kind of environment, it must be different from environment to environment, because different application environments may not have the same requirements on identification rate, and this must be accumulated by experience.
Although there are a variety of license plate recognition system on the market, the use of the product and structure, can save a lot of wasted money and time, but more importantly, the project and system integrators need to cooperate with and understand, rather than blindly focus on a brand is better, cheaper, nothing is cheaper.
    In addition, whether the license plate recognition system can make the most use of the software technology, the camera and the field construction ability, also have a great deal to do. Users may request the manufacturer to the scene after the exploration, the paper puts forward establishing planning, the assessment should set up the first place, using an Angle, whether you need to set up auxiliary light source, etc., offer again, by these actions, in addition to assess in advance ability and users themselves can also achieve product learning and education training, management, in the future will be more clearly know the restrictions on the use of the products and the relevant measures.
 More info in wikipedia

License plate recognition parking lot system - parking lot equipment | parking lot management equipment | parking lot system equipment, automatic license plate recognition principle, schematic diagram of license plate recognition process, schematic diagram of license plate recognition process. Automatic license plate recognition is a pattern recognition technology for automatic recognition of license plate number and color by using dynamic video or static image of vehicle. Its hardware foundation generally includes trigger equipment (monitoring whether the vehicle enters the field of view), camera equipment, lighting equipment, image acquisition equipment, processor for recognizing license plate number (such as computer), etc. its software core includes license plate location algorithm, license plate character segmentation algorithm and optical character recognition algorithm. Some license plate recognition systems also have the function of judging whether there is a car through video images, which is called video vehicle detection. A complete license plate recognition system should include vehicle detection, image acquisition, license plate recognition and so on.


When the vehicle detection section detects the arrival of the vehicle, it triggers the image acquisition unit to acquire the current video image. The license plate recognition unit processes the image, locates the license plate position, segments the characters in the license plate for recognition, and then forms the license plate number output. (1) Vehicle detection: vehicle detection can adopt buried coil detection, infrared detection, radar detection, video detection and other methods. Using video detection can avoid damaging the road surface, no additional external detection equipment, no need to correct the trigger position, save expenses, and is more suitable for mobile and portable applications. For video vehicle detection, the system needs to have high processing speed and adopt excellent algorithms to realize image acquisition and processing without losing frames. If the processing speed is slow, it will lead to frame loss, so that the system cannot detect the vehicle with fast driving speed.
At the same time, it is difficult to ensure that the recognition processing is started at the position conducive to recognition, which will affect the recognition rate of the system. Therefore, it is difficult to combine video vehicle detection with automatic license plate recognition. (2) License plate number and color recognition for license plate recognition. The following basic steps are required: 1) license plate positioning, positioning the license plate position in the picture; 2) License plate character segmentation, which divides the characters in the license plate; 3) License plate character recognition, recognize the segmented characters, and finally form the license plate number. In the process of license plate recognition, the recognition of license plate color is based on different algorithms and may be realized in the above different steps. It usually cooperates and verifies with license plate recognition. 1) In the natural environment of license plate location, the background of vehicle image is complex and the illumination is uneven.
How to accurately determine the license plate area in the natural background is the key of the whole recognition process. Firstly, a large-scale correlation search is carried out on the collected video image, and several regions in line with the characteristics of the vehicle license plate are found as candidate regions. Then these candidate regions are further analyzed and evaluated. Finally, a best region is selected as the license plate region and separated from the image. 2) After the license plate character segmentation completes the location of the license plate area, the license plate area is divided into a single character, and then recognized. Character segmentation generally adopts vertical projection method.
Since the projection of characters in the vertical direction must be near the local minimum value at the gap between or within characters, and this position shall meet the character writing format, characters, size restrictions and some other conditions of the license plate. The vertical projection method has a good effect on character segmentation in automobile image in complex environment. 3) At present, license plate character recognition methods mainly include template matching algorithm and artificial neural network algorithm. Based on the template matching algorithm, firstly, the segmented character is binarized and its size is scaled to the size of the template in the character database, then it is matched with all templates, and the best matching is selected as the result. There are two algorithms based on artificial neural network: one is to extract the features of characters, and then use the obtained features to train the neural network distributor; Another method is to input the image directly into the network, and the network automatically extracts the feature until the recognition result is obtained. In practical application, the recognition rate of license plate recognition system is also closely related to license plate quality and shooting quality.


The quality of license plate will be affected by various factors, such as rust, stain, paint peeling, font fading, license plate shielding, license plate inclination, highlight and reflection, multiple license plates, false license plates, etc; The actual shooting process will also be affected by environmental brightness, shooting mode, vehicle speed and so on. These factors reduce the recognition rate of license plate recognition to varying degrees, which is the difficulty and challenge of license plate recognition system. In order to improve the recognition rate, in addition to constantly improving the recognition algorithm, we should also find ways to overcome various lighting conditions to make the collected images most conducive to recognition.

License plate image recognition is an indispensable part of modern intelligent transportation and plays a powerful role in promoting the construction of smart city. With the increasing construction of domestic expressways, urban roads and parking lots, the requirements for traffic control and safety management are also increasing. In order to meet such a demand, the traffic is controlled and managed conveniently, quickly, accurately and effectively. Therefore, license plate image recognition technology has particularly important practical significance in public safety and traffic management. At present, the automatic license plate image recognition system is developing towards high recognition, high speed and embedded. In order to improve the recognition rate of the system, in practical application, people always expect the license plate recognition system to recognize the license plate characters accurately and quickly. Therefore, tigerwong developed and added some hardware detectors and other auxiliary equipment. From the application effect of the existing system and the whole society, the conclusion is very impressive, The improved system can weaken the uncontrollable influence caused by visible light and bad weather, and the automatic information processing ability is continuously improved. The license plate recognition system is actually applied to traffic engineering. At first, it was mainly used in expressway toll collection auxiliary system to reduce the loss of traffic toll revenue. Later, it gradually developed into a variety of application fields such as urban transportation, parking lot management, vehicle registration verification, vehicle statistics, safety management and access control management. License plate recognition technology plays an important role in promoting the development of intelligent transportation system and transportation industry, It has broad market prospects. 1. Application of license plate image recognition technology in the field of expressway. Expressway is the earliest and largest field of license plate image recognition technology. Generally, the license plate image is collected and recognized at the entrance of the expressway, and the person who writes the recognition result into the pass card (ticket) transmits it to each exit station through the network. When the vehicle arrives at the exit, the license plate image is collected and recognized again, and the recognition result is compared with the entrance recognition result, so as to prevent or detect fee evasion such as card reversing, card changing and card changing. 2. Application of license plate image recognition technology in the field of parking lot charge management parking lot charge management system: it is used to recognize and match the license plates of incoming and outgoing vehicles and realize automatic timing and billing management. Parking management is becoming a serious problem in urban traffic management, and people's voice for intelligent parking lot management is rising day by day, An intelligent car parking management system can be built through the license plate recognition system. Therefore, it has great market potential in shopping malls and office buildings in large and medium-sized cities. Tigerwong pointed out that having a correct recognition rate is the most important and fundamental indicator of the license plate recognition system. Without a satisfactory correct recognition rate, no matter how fast the recognition speed is, it is meaningless. Tigerwong's goal in the field of license plate image recognition is to achieve high recognition, high speed and multi-element marking. Tigerwong is a leading supplier of comprehensive solutions for intelligent parking management system management in China. Its products include license plate recognition system, parking lot system, car parking management system, parking space guidance system, etc. if you have any problems with license plate recognition system, you can call tigerwong and hope to help you!

With the increase of vehicles in major cities, many residential areas, commercial squares, shopping centers, airports and other major parking lots have been transformed successively, which not only transforms the traditional paper ticket and card swiping parking lots into intelligent parking lots, but also introduces the very hot license plate recognition technology. After the development of science and technology over the years, the parking lot license plate recognition system has undergone great changes in product appearance and technology, which really makes the parking lot system degenerate in identity recognition. At present, license plate recognition parking lot system is considered to be a set of car parking management system which is more convenient for management and fast traffic. Because it has the advantages of high recognition rate and fast traffic, it is favored by many users. License plate recognition technology is mainly combined with the electronic system to identify vehicles without stopping the charging system. Vehicles in and out of the crossing do not need to stop, so as to realize automatic identification and automatic charging of vehicle identity. In the parking lot management, the license plate recognition system has greatly improved the efficiency of vehicle access, and has become an unattended fast track. There is no need to pick up the card and parking. It is changing the management mode of access to the parking lot. License plate recognition is an important part of modern intelligent transportation system, which is widely used. Based on digital image processing, pattern recognition, computer vision and other technologies, it analyzes the vehicle image or video sequence taken by the camera, and obtains the unique license plate number of each vehicle, so as to complete the recognition process. Through some follow-up processing means, the functions of parking lot charge management, traffic flow control index measurement, vehicle positioning, automobile anti-theft, expressway overspeed automatic supervision, red light running electronic police, highway toll station and so on can be realized. The vehicle license plate number is the only identification of the vehicle, and entering the parking lot often depends on the license plate number for registration and payment. The parking lot system added with the license plate recognition technology sets the access authority through the recognition of the license plate number of the incoming and outgoing vehicles. It has gradually developed into a complete access management system in the parking lot, which has the advantages of low cost, simple installation Parking safety and other characteristics. Security and convenience are the two cores of the license plate recognition system. With the increase of vehicles, the parking lot system has become the only tool for each place to manage vehicles. Its diversified application has made it realize the functional transformation from manual management to intelligent management. Firstly, compared with other traditional parking lot systems, the license plate recognition parking lot system eliminates the process of people parking and picking up cards. At a distance from the vehicle, the license plate recognition HD camera can capture the license plate number of the vehicle entering the parking lot, and the gate will open automatically. Secondly, compared with other parking lot systems, the license plate recognition parking lot system adopts the expressway gate, The bar lifting time of the road gate within three meters can be fully lifted in one second, which greatly reduces the time for people to enter the parking lot, which is also one of the reasons why people like it. Tigerwong parking equipment supplier has focused on parking equipment for many years! If you have any questions about the parking system, welcome to consult and communicate.