License plate technology, seemingly simple at first glance, is now at the heart of a vast system combining traceability, automated inspection, and road safety. From optical recognition to radio frequency identification, several devices are used to read and process these plates, particularly by law enforcement and toll systems.
License plate technology, seemingly simple at first glance, is now at the heart of a vast system combining traceability, automated inspection, and road safety. From optical recognition to radio frequency identification, several devices are used to read and process these plates, particularly by law enforcement and toll systems. But how do these technologies work? And what are the implications for motorists?
Since 2009, the Vehicle Registration System (SIV) has profoundly transformed license plate management in France. Each vehicle now receives a unique identifier, assigned for life, which facilitates administrative tracking throughout its existence. This standardized system has also enabled the development of automatic license plate reading technologies (ANPR, LPR) by providing a reliable, structured, and constantly updated database. This direct link between digital registration and road monitoring tools is at the heart of numerous technological developments, both in terms of security and automated control.
How does the license plate system work?
In France, each vehicle is registered through the Vehicle Registration System (SIV). Once assigned, this unique number is displayed on two metal or plastic plates (front and rear), in a standardized format. These plates must comply with strict rules:
- Standardized color and typography,
- Characters readable at a certain distance,
- The presence of the registration number, the regional logo, a nd the department number.
Their main role is the immediate and universal identification of the vehicle, whether in circulation, during a check, or in the event of an offense.
But today, this function is no longer limited to the human eye. Plates are scanned, interpreted, and cross-referenced with databases in real time.
What are ANPR technology and LPR technology?
ANPR (Automatic Number Plate Recognition) and LPR (License Plate Recognition) systems are optical recognition technologies. Using high-definition cameras coupled with image processing algorithms, they allow:
- Instantly read a plate,
- Identify the vehicle number,
- Access databases to check insurance, technical inspection, or even search for a stolen vehicle.
These technologies are used by:
- Automatic radars,
- The toll gates,
- CCTV cameras,
- Police or private parking company vehicles.
License Plate Technology The Differences Between ANPR, LPR, and RFID
• ANPR / LPR (automatic license plate recognition)
These are technologies based on the analysis of images captured by cameras. The software detects the plate in the image, reads the characters using an optical recognition system, and then extracts the useful information.
They are widely used for traffic control, parking, tolls, and criminal investigations. However, they require good visibility and a compliant license plate (clean, unobscured, well-lit).
• RFID (Radio Frequency Identification)
Unlike ANPR/LPR, RFID does not require an image to identify a vehicle. It relies on a transmitter chip placed in or on the vehicle, which communicates via radio waves with a fixed sensor.
It allows for faster detection, even in low-visibility conditions (fog, darkness), but requires specific equipment on the vehicle. This technology is mainly used in private or experimental contexts (industrial zones, vehicle fleets, secure parking lots).
Advantages and disadvantages of each license plate technology
ANPR / LPR
Two major advantages:
• Can be used without on-board installation. This means that any vehicle, even an older one, can be identified without modification.
• Easy to deploy with fixed or mobile cameras. They are already in place on many public facilities and require little additional infrastructure.
Two major drawbacks:
• They are highly dependent on the readability of the plate. A dirty, damaged, or tilted plate can cause reading errors.
• Their accuracy decreases in certain weather conditions (heavy rain, snow, backlighting). This can limit their effectiveness in open and uncontrolled environments.
RFID
Two major advantages:
• Very fast and reliable, even at high speeds or in complete darkness. RFID gates can process several vehicles per second without stopping.
• Less susceptible to fraud by masking or altering the plate. As long as the chip is working, it emits a signature that is difficult to falsify.
Two major drawbacks:
• Costly to install on vehicles and infrastructure. A chip must be integrated, and compatible readers must be installed.
• Potential privacy risks. An RFID chip can be read remotely, raising questions about geolocation and data collection.
License plate technology How do the police or radars scan them?
Fixed and mobile speed cameras are now all equipped with an ANPR system. As soon as a vehicle drives past, the camera captures the image of the license plate, then the software analyzes the photo to identify the number.
The plate is then crossed with the bases of the Ministry of the Interior :
- Vehicle reported stolen?
- Insurance expired?
- Technical inspection not up to date?
- Unpaid fines?
In some cases, radars are also able to calculate an average speed, detect parking or traffic violations.
How to make your license plate unreadable by radar?
It is important to know that attempting to make a license plate illegible is illegal . The use of reflective sprays, plastic films, or even intentionally tilting the plates is prohibited. This constitutes an offense punishable by a fine of up to €750 , with the risk of immobilization of the vehicle.
Law enforcement is equipped to detect this type of fraud, including using infrared cameras.
Why not display your license plate online?
• Avoid identity theft
Posting your license plate on an ad or shared photo can allow fraudsters to clone it. It can be reproduced on another vehicle, often of the same make or color, to commit offenses or drive without being identified. This is called a duplicate .
In the event of fines or accidents caused by this duplicate, it is the real owner who is contacted by the authorities. They will then have to prove that they were not at the wheel, which can be a long and stressful process.
• Fraudulent resale
Scammers may reuse photos of your vehicle to create fake listings. They then pretend to sell the car and request fraudulent deposits from unsuspecting buyers.
This can damage your reputation if your name is associated with a scam, and lead to legal action if the victim turns against you.
• Remote monitoring or profiling
Some websites allow you to find information about a vehicle based on its license plate: date of registration, exact model, etc. Malicious individuals could use this data to track you, scam you, or organize a targeted theft.
