Automatic License Plate Recognition (ALPR) is an intelligent system that uses optical character recognition on images to read vehicle license plates. It can be used from a distance and does not require contact or interaction with the vehicle itself. As a result, it is an effective tool for law enforcement and security purposes, such as detecting stolen vehicles or tracking the movements of suspicious criminals.
Have you ever wondered how those cameras that take your picture as you drive through a toll booth know exactly who you are? It’s all thanks to Automatic License Plate Recognition (ALPR) technology. This article will explain how ALPR systems work, how to read license plates from footage, and why this technology is becoming increasingly common worldwide.
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What is ANPRS, or Automatic Number Plate Recognition System?
Automatic Number Plate Recognition System (ANPRS) is a technology that uses optical character recognition on images to read vehicle license plates. It can be used from a distance and does not require contact or interaction with the vehicle itself. As a result, it is an effective tool for law enforcement and security purposes, such as detecting stolen vehicles or tracking the movements of suspicious criminals.
How does ANPR work?
ANPR systems typically consist of an IP camera, a processor, and software that is capable of reading license plate numbers. The camera captures images of passing vehicles, and the processor utilizes optical character recognition to convert the images into text. The software then compares the license plate number with a database of known vehicles, such as a stolen vehicle database. If there is a match, the system can generate an alert or record the event in the appropriate collection.
Disadvanteges of ALPR systems.
Despite the many advantages of ALPR systems, there are certain drawbacks to consider. For example, these systems can be costly to install and maintain. Additionally, they require a certain amount of computational power, which can result in slower response times. Lastly, they can generate false results, potentially leading to the wrongful detention and questioning of innocent individuals. The camera requires a maximum viewing angle of 30 degrees, and it is important to install it relatively low. There is also no Wi-Fi camera version available. If you want to implement a wireless ANPR monitoring system, you will need to use a Wi-Fi bridge or an access point.
Despite these drawbacks, ALPR systems offer a range of benefits that make them an attractive option for law enforcement and security purposes. As these systems become more prevalent and advanced, they are likely to play an increasingly significant role in public safety.
What does an effective license plate recognition system include?
A effective license plate recognition (LPR) system includes several key components. Firstly, a high-quality IP camera is needed, capable of capturing clear images of license plates from a significant distance. Secondly, a processor is required to quickly process the images into text. Thirdly, software is needed to compare the license plate number with a database.
How does a license plate recognition (LPR / ANPR) system work?
A license plate recognition (LPR / ANPR) system is a technology that uses optical character recognition to read vehicle license plates. The system consists of a camera, a processor, and software that can read license plate numbers. The camera captures images of passing vehicles, and the processor uses optical character recognition to convert the images into text. The software then compares the license plate number with a database of known vehicles. If there is a match, the system can generate an alert or take further action.
Functions of an ANPR System
ANPR (Automatic Number Plate Recognition) systems are becoming increasingly popular worldwide due to the range of advantages they offer compared to traditional license plate reading methods. For instance, they can be used in all weather conditions and do not require physical contact with the vehicle. Additionally, they can track the movement of multiple vehicles simultaneously, which is not feasible with manual license plate reading. Finally, they can be integrated with other systems such as GPS tracking systems to provide even more information about a vehicle’s whereabouts.
Where to apply a license plate reading camera?
There are numerous locations where license plate reading cameras can be applied, including:
- Parking lots
- Toll booths
- Border crossings
- Law enforcement checkpoints
- Security gates
- Residential surveillance
- Urban surveillance
- Warehouse monitoring
The range of applications is vast. I’ve mentioned only a few of the most popular ones. CCTV cameras for LPR/ANPR operate within an IP surveillance system. This should be taken into account when designing a CCTV monitoring system.
Dahua ANPR Cameras
DAHUA ITC237-PW6M-IRLZF1050-B IP CAMERA
- Long-range ANPR camera
- GS-CMOS image sensor
- Resolution: 1920 x 1080 – 2MP
- Lens: 10-50mm motozoom
- Video Compression Standards: H.265/H.264M/H.264H/H.264B/MJPEG
- Integrated design, IP67-rated
- WDR motozoom lens – 96 dB
- Wide Dynamic Range (WDR) – 3D Lighting Range
- Digital Noise Reduction (DNR)
- Built-in Deep Learning LPR engine
- Image recording on the card during network failure and subsequent synchronization
- Image analysis: License Plate Recognition, vehicle type recognition, vehicle logo recognition, non-license plate vehicle detection, time and address overlay (channel position), lane information (number/direction), plate information (number and color), vehicle information (speed, color, type)
- ICR – Mechanical infrared filter
- Day/Night mode (color/B&W/auto)
DAHUA ITC437-PW6M-IZ-GN IP CAMERA
DAHUA ITC437-PW6M-IZ-GN IP camera is a higher-resolution version compared to the previous camera.
ANPR camera, 1/1.8” CMOS sensor, Maximum resolution: 2688 × 1520@25 fps, 10mm–50mm moto-zoom lens, WDR (96 dB), 6 IR LEDs up to 30m, intelligent functions: LPR, color, type, logo, driver and passenger characteristics, IP67-rated.
Kenik ANPR Cameras
KENIK KG-2050TZS-IPR IP CAMERA
- Resolution: 2MP (1920×1080) at 25fps
- 1/2″ Sony Super STARVIS IMX385 image sensor
- Compression: H.265+/H.264+
- WDR (120dB), Day/Night (ICR), 3DNR, AWB, AGC, BLC
- Lens: 3.6-11mm (motozoom)
- Smart IR illuminator up to 50m
- Smart Light white light LEDs
- MicroSD card reader (up to 128GB)
License Plate Recognition (LPR)
Intelligent Video Analysis (IVA) features: Intrusion detection, line crossing, region exiting, region entering, fast-moving, object disappearance, object left behind, crowd detection, parking detection, face detection, loitering detection, sound detection, defocus detection, scene change detection, line crossing statistics
- Defog and ROI functions
- 3 streams
- Direct recording to NAS server
- Alarm input/output
- Audio input/output
- BNC test output
- Dual power supply: 12V DC / PoE (802.3af)
- IP66-rated housing
- Supports ONVIF 2.6 standard
- Mobile viewing on smartphones (Android, iPhone)
- Free software with Polish language support for computer recording
Kenik IP camera is ideal for high-quality image surveillance systems. The camera features a large 1/2″ 2MP sensor and advanced H.265+ compression for capturing detailed images day and night. The modern infrared illuminator with SMD LEDs ensures full illumination even in complete darkness. Additionally, users can benefit from intelligent image analysis for enhanced security of protected premises, which can be applied in home monitoring, store monitoring, warehouse monitoring, and other types of facilities. Various functions such as DEFOG and ROI, as well as hardware-based WDR, ensure a clear and distortion-free image for easy identification of people or objects. Moreover, the camera can operate in the cloud, and the connection is straightforward. Users can check the monitored premises from anywhere in the world using their smartphones. The camera is equipped with a motozoom lens with a focal length of 3.6-11mm, allowing remote adjustment of zoom and camera viewing angles based on the observed object. An important advantage is the support for NAS servers and the ability to directly record video footage on a network drive. The camera detects vehicles traveling at speeds up to 30 km/h at a distance of 5 to 10 meters.
Hikvision ANPR Cameras
Hikvision LPR (License Plate Recognition) cameras are designed to capture vehicle license plates in various lighting conditions, both day and night. The cameras utilize advanced algorithms to enhance license plate images and increase recognition accuracy.
LPR technology allows for seamless identification of vehicles moving at high speeds and offers simultaneous identification for 2 lanes of traffic, ensuring optimal read efficiency. The technology employed in Hikvision devices is characterized by excellent capture, reading, and recording speed of license plate numbers. The manufacturer claims that Hikvision LPR cameras can identify a vehicle approaching at a speed of 120 km/h and capture 99% of them, with correct identification of the numbers in 95% of cases. The ability to build unique lists of wanted vehicles (white list) or unwanted vehicles (black list) is one of the main advantages of LPR software. For example, if a license plate number appears on one of several lists (up to 2048 numbers are allowed), an active alarm event can be triggered: notifying the monitoring center, sending a photo to FTP, memory card, or NAS server. Additionally, when combined with a recorder and automatic gate opening, the LPR service allows for vehicle identification and automatic gate or barrier opening. The LPR function enables the identification of license plates from all over Europe, the Middle East, Africa, Asia, as well as North and South America. For optimal LPR function, Hikvision recommends using their IP recorders from the K and I series. The iVMS-5200 software is used for professional use of cameras with LPR function. It is a paid version that includes a specially initiated module significantly expanding the capabilities of the free iVMS-4200 version.
Hikvision IP Camera iDS-2CD7A46G0-IZHSY (8-32mm)
Sensor: 1/1.8″ CMOS Progressive SCAN Resolution: 4MP 2680 × 1520 Lens: 8-32mm M-Zoom Sensitivity: 0.001 Lux Image Compression: H.265+/ H.265/ H.264/ H.264/ MJPEG Field of View (FOV): Horizontal FOV: 42.5° to 15.1°, vertical FOV: 23.3° to 8.64°, diagonal FOV: 49.6° to 17.3° Infrared Illuminator: IR50m SD Card Slot: Yes, up to 256GB Relay Input/Output: 2/2 Wiegand Interface: Yes Plate Memory: Up to 10,000 records Motorcycle Plate Recognition: Yes (in checkpoint mode) IP Rating: IP67 Mechanical Strength: IK10 Operating Temperature: -30°C to 60°C Power Supply: 12V DC, PoE Dimensions: Ø144 × 347 mm Weight: 3060g
The Hikvision iDS-2CD7A46G0-IZHSY model is a camera from the DeepinView series. The camera’s software is capable of detecting and counting queues of people, as well as determining the waiting time for each individual.
Hikvision IP Camera iDS-2CD7A26G0-IZHS (2.8-12mm)
Sensor: 1/1.8″ CMOS Progressive SCAN Resolution: 2MP 1920 × 1080 Lens: 2.8-12mm M-Zoom Sensitivity: 0.001 Lux Image Compression: H.265+/ H.265/ H.264/ H.264/ MJPEG Infrared Illuminator: IR50m SD Card Slot: Yes, up to 256GB Relay Input/Output: 2/2 Wiegand Interface: Yes Plate Memory: Up to 10,000 records Motorcycle Plate Recognition: Yes (in checkpoint mode) IP Rating: IP67 Mechanical Strength: IK10 Operating Temperature: -30°C to 60°C Power Supply: 12V DC, PoE Dimensions: Ø144 × 347 mm Weight: 3060g
This camera has similar specifications to the previously mentioned model, with the only difference being a lower resolution.
Origin of the ANPR System
Automatic Number Plate Recognition (ANPR) systems were first developed in the 1970s by the British Police. The system was designed to assist officers in rapidly identifying stolen vehicles. However, license plate recognition cameras did not gain widespread use until the 1990s when they began to be utilized for law enforcement and security purposes.
Countries Covered by License Plate Identification
License plate identification is employed in many countries worldwide, including the United Kingdom, United States, Canada, Australia, New Zealand, and the European Union. In some cases, this system is used for law enforcement purposes, while in others, it is utilized for toll collection or security purposes.
License Plate Reading Software
In the United States, license plate readers are used by law enforcement agencies to track the movements of suspicious criminals. The program has been controversial and faced several lawsuits. However, the program has proven effective in tracking fugitives and wanted criminals.
Alnet Netstation is a network software for digital image recording for 8 IP cameras with license plate recognition (LPR) function.
Key features include:
- Compatibility with IP cameras from well-known manufacturers
- LPR (license plate recognition) analysis module
- Support for ONVIF and RTSP
- Multi-layer e-maps
- Multi-monitor mode
- Advanced PTZ control
- Audio recording
- Digital zoom
- Intuitive operation
A part of the system is the vehicle license plate identification module. LPR is the most advanced and adaptable technology for reading and identifying vehicle license plates.
Regardless of weather conditions or the condition of license plates, LPR works thanks to innovative video identification methods. The system can read 25 plates per second, allowing for vehicle identification in motion.
The identification accuracy has been tested in an experiment and is practically excellent (99.95%).
The identification precision is calculated independently for each character on the screen. When LPR is integrated with VDRS, the system creates a database with recognized plates and inserts bookmarks in the archives. This solution allows for quick searching of the start of a video sequence with a specific vehicle.
LPR generates information such as the license plate number, detection time and date, optional plate photo, and multiple vehicle photos, such as the driver’s shot or rear view.
The internal database can be used to record vehicle data, such as the license plate number, car make, owner, and entry/exit time. This information helps in efficient management of parking entrance routes while simultaneously monitoring the arrival and departure timestamps.
LPR can communicate with other databases to search for data on recognized vehicles. The program’s fully open architecture allows for full interoperability with other systems.
Automatic license plate recognition system is a powerful tool that can be used for various purposes. It is important to properly configure the system to maximize its benefits.
With the right configuration, the system can be used to track vehicles, fugitives, and wanted criminals.
The system is also useful for managing parking entrance routes and monitoring arrival and departure times.