What is ALPR?

ALPR can stand for a few different things:

• Automated License Plate Recognition
• Automatic License Plate Recognition
• Automatic License Plate Reader

What does ALPR do?

ALPR consists of a camera, a computer (laptop or separate processor) and specialized software. The camera is always looking for license plates in every frame. When it finds one, it takes a photo of the vehicle and another of just the license plate. It then uses optical character recognition (OCR) to read the plate.

How is it used?

ALPR license plate recognition systems are capable of a few different configurations:

1. In-car mobile - permanently mounted on a law enforcement vehicle.
2. Temporary vehicle mount - done with suction or magnets.
3. Static system - traffic pole, under bridges.
4. Temporary roadside - camera mounted on a tripod attached to a laptop.
5. Trailer - a camera mounted on a law enforcement trailer such as a speed trap with a display.

The license plate recognition is only the start of the process. ALPR has the potential to change the nature of law enforcement.

• ALPR can recognize license plates at high speeds, in low light conditions, while driving.
• ALPR can recognize multiple plates at once, and even more if multiple cameras are installed on a vehicle facing different directions.
• Recognized plates can be instantly compared with a list of known criminals and alerts returned when a match is found. All the operator has to do is drive around and wait for an alert.
• The hotlist can be updated remotely. An amber alert vehicle can be instantly updated on the ALPR system before the driver even knows about it. It can then look through historical data for sightings of the vehicle that day for instance.

What about privacy?

Privacy is a big concern with ALPR. The question is whether license plate recognition is doing anything that a person can't do already. ALPR doesn't look up any personal information unless it finds a match on the list of wanted vehicles. It's basically writing down a license plate and when and where it saw it, something anyone can do, only many times more efficiently. It frees up the driver to focus on the road. Some law enforcement agencies require the drivers to run these checks manually already at stop lights. ALPR simply automates what they already do, but since the checks are in reverse, it actually reveals less private information.