Fredrik Nilsson is General Manager, Americas for IP video company Axis Communications and a regular contributor to SecurityInfoWatch.com, IPSecurityWatch.com and Security Technology & Design magazine.

Picture courtesy of Genetec Inc.

Security console demonstrates how license plate recognition (LPR) automatically focuses on license plate.

Photo courtesy Extreme CCTV

Specialty cameras capture a clear image of the license plate at all times of the day. A second camera can provide an overview image of the car itself.

Photo courtesy Vigilant Video

A facial recognition system isolates the face in a frame and compares features to those in a database.

In the previous two months, I devoted columns to two broad categories of intelligent video (IV) applications: pixel-based video intelligence and object-based video intelligence. (See the articles Applying Pixel-Based Intelligent Video and Applying Object-based Intelligent Video). Pixel-based IV applications generally apply to detecting motion and camera tampering. Object-based IV applications are generally used to classify and track objects and people. A third category of IV applications combines techniques from both pixel- and object-based analytics to extract information from a video for specialized applications. These specialized IV tasks cover the range from automatic recognition of license plate numbers and individual faces to smoke and fire detection.

License plate recognition (LPR)

Having the intelligence to automatically recognize a license plate number can boost a facility's perimeter and interior security. It can also provide a wealth of information for astute retailers to leverage for target marketing.

• Access control. LPR could be used to restrict entry to vehicles with particular plate numbers, an appropriate application for high-security locations like embassies.

• Criminal investigation. LPR could help law enforcement locate a vehicle suspected of being involved in a crime by automatically look for vehicles with a particular plate number.

• Intelligent parking. Using LPR to automatically track vehicles entering a parking lot would be less expensive than a parking ticket kiosk. The technology could also automatically monitor how long a particular vehicle stays in a parking lot, which could help attendants determining if a vehicle has been abandoned or a shopper has monopolized reserved space beyond the legal time limit.

• Retail marketing. LPR could help retailers identify frequently cars parked in front of certain stores. This information could be used to analyze shopper demographics or design marketing programs to reach consumers in the right geographical areas.

How it works

License plate recognition is a multi-step process:

1. Find the car in an image - either through blob recognition or video motion detection.

2. Isolate the actual license plate - through object recognition and classification.

3. Extract the letters and numbers from the license plate - through image analysis.

4. Transform the collection of pixels into a stream of letter and numbers - using optical character recognition.