License Plate Recognition Surveillance Cameras


License plate recognition, is a feature on some software that can detect, read, and store video of a car’s license plate. Used primarily in traffic monitoring in parking lots and gated security entrances, this allows the camera to capture a license plate number which is then compared to a database.

How License Plate Recognition Works

License plate recognition works when your camera captures video of a vehicle’s license plate and then either stores it for later review or runs the image through video analytics software to compare it to a database of stored license plate numbers.

If your database finds a match, your system can be set up to send you alerts. These alerts can be sent to your email or mobile phone, allowing you to know instantly, from anywhere, if your system finds something.

For license plate recognition to work, your camera needs a few specific things:

  • The angle of the camera is extremely important, because a camera that’s installed too high cannot see the license plate
  • The distance from the camera to the car must also be considered – while a camera may be able to zoom in quite a distance, you want to minimize the distance between camera and car
  • Lighting is also important – whether you install lights or use the camera’s built-in IR, you will need additional lighting at night
  • The speed of oncoming traffic must be low enough that the camera has enough time to focus on the license plate, often times no more than 35 mph depending on the angle, distance, and lighting

In addition, you’ll need to pay attention to the quality of the image. To be used as legal evidence, your video may need to meet standards set by your local law enforcement; one requirement might be that the captured license plate image be at least 15 pixels tall, to ensure clarity. A pixel counter, a feature included on some cameras, will help you meet these requirements.

How License Plate Recognition Can Help You?

Situations that call for license plate capture may be very specific, but this feature is incredible important if you need to:

  • Secure an area, such as a military base or research facility
  • Monitor gated entrances & parking lot traffic
  • Track a known suspect’s vehicle
  • Find a stolen vehicle or car involved in a crime
  • Enforce parking laws, including time limits or reserved spaces

A popular application is access control for parking structures. A camera is placed at the entrance gate, and will automatically record an approaching car’s license plate to compare it to a database of approved visitors. If that license plate is on the database, the gate will open and allow the car to enter.

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