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ELSAG North America is part of Selex ES, a Finmeccanica company.
An Automatic License Plate Reader (ALPR) is an image-processing
technology used to identify vehicles by their license plates.
It is a special form of OCR (Optical Character Recognition)
where algorithms are employed to transform the pixels of the digital
image into the text of the number plate Systems commonly use infrared
lighting to allow the camera to take the picture at any time of day.
There are many applications for License Plate Readers
such as traffic and parking management, tollbooth operations and
area-access control. One of the fastest growing applications is the
deployment of ALPR systems by law enforcement agencies across the
country to identify persons or vehicles whose license plates are
connected to a crime or infraction. Cameras, mounted to police vehicles
or stationary structures such as gates or bridges, automatically
take photos of license plates at the rate of hundreds per minute.
The characters in the photo of the plate are then translated into
letters and numbers and compared to law enforcement databases of
registered vehicles known to be or suspected of being involved with
crimes or infractions. If a license plate that was read matches an
entry on a database, the license plate reader system will alert the
officer (if the LPR system is mounted to a police vehicle) or command
center (if data is transferred to a remote management facility) that
a suspect vehicle is in the immediate area of that LPR system.
License plate recognition systems utilize algorithms in order to
identify a license plate, take a clear image, translate its characters
and identify the state that issued the plate. The better the algorithms,
the more accurate the information.
Generally speaking, License Plate Readers (LPRs) can record plates
at about one per second at speeds of up to 100 MPH and they often
utilize infrared cameras for clarity and to facilitate reading at
any time of day or night. The data collected can either be processed
in real-time, at the site of the read, or it can be transmitted to
remote center and processed at a later time.
An automatic license plate reader is also known
by the following terms:
- LPR Technology
- License Plate Recognition
- License Plate Camera
- Automatic Vehicle Identification
- Car Plate Reader
- OCR (Optical Character Recognition)