Also known as Licence Plate Recognition (LPR) or Automatic Licence Plate Recognition (ALPR), ANPR is typically the process of sending an image or stream of images from a camera to a computer or processor. This can be a processor within the camera or a separate local or remote PC. The ANPR recognition software is usually referred to as the ANPR Recognition Engine which examines each image in turn and performs a sequence of operations. These include locating the plate, finding and separating all of the plate characters and then attempting to interpret each character by matching against a known template or using neural processes much like a human brain would do.
What does ANPR do? Once a number plate has been read you will need to transmit the plate read with all of the metadata (includes plate text, lane id, location id, time & date and associated images etc) on to an application program running remotely or on the same processor as the plate was processed on. Sometimes plates are transmitted from hundreds of cameras to a central PC on the same site for further matching, processing or storage. ANPR recognition technology can be very clever but for most people, they are not really interested in what happens ‘under the bonnet’, they want good read accuracy and an application that delivers the solution for their system requirements.
ANPR Application Software Application Software is everything when it comes to delivering an ANPR solution. All the clever ANPR recognition stuff is not really that important without actually doing something with the results. Car Park Management, Access Control, Security Monitoring with alerts based upon known criminals and suspicious vehicles are just the headlines. User requested bespoke solutions are driving application development in ANPR at a great pace - so if you are looking at a set of requirements this is a good point to focus on.
ANPR Access Control ANPR provides additional security over the common problem of access control proximity key fobs being cloned by the locksmith in a corner shop. This generally would not apply to the bigger industry brands but we ourselves have been surprised to learn that many RFID tokens can be cloned so easily. Car park users can be given access on a category rule basis that determines days and times for access whilst a Visitor can be given a timed ‘virtual permit’ to just some of a site’s car parks that will elapse after the time window has passed.
ANPR Security Monitoring of incoming vehicles to a site, spotting repeat visitors engaged in driving round a perimeter for hostile surveillance with pop-up alerts or emails to a smartphone can all be achieved very simply using ANPR. Arriving VIPs or expected visitors’ plates can create audible alerts to make sure they get the appropriate attention and treatment as they arrive.