Today ANPR (Automatic Number Plate Recognition), once the sole preserve of the police in their efforts to deal with traffic law violations and other criminal activity, is increasingly being deployed by security managers to control risk and heighten security at commercial and public sector sites. When it comes to the application of ANPR, there is an ever-growing range of scenarios where this technology is having a positive impact, whether it is a petrol station forecourt, to deter and prosecute customer ‘drive-offs', or the effective control of site access for a large-scale manufacturing plant to prevent unauthorised entry to commercially critical areas. In fact most observers would agree that ANPR is one of the most pervasive, reliable and commercially viable of all the available content analysis solutions.
Looking in more detail at the typical end user requirements for ANPR technology, these are likely to include some of the following: the ability to identify and record the licence plate details of all vehicles coming into, and/or leaving a specific area; the potential to record associated video images for a period of time and to save this data for later analysis; the control of access to a site by identifying vehicle license plate details and only activating a barrier for approved vehicles and to generate billing information for parking, traffic monitoring and congestion charging.
In operation, ANPR can be readily integrated with existing CCTV cameras, deployed in specifically designed ANPR cameras or used by the authorities in conjunction with speed/road safety cameras. The underlying ANPR capability may be delivered through PC-based systems or, increasingly, by embedded solutions with processing conducted either in a specialised ANPR camera - which has advantages in terms of speed of processing - or by taking CCTV camera images and then using a DVR (Digital Video Recorder) and a video analytics package to produce the same result.
Where a specialised ANPR camera is being installed, typically this will be in concert with an overview camera (if a suitable CCTV camera is not already in situ) mounted alongside. The overview camera allows a colour image of a specific vehicle to be captured for evidential purposes and associated with the licence plate data from the ANPR camera in the same file, so aiding any future prosecution.
In terms of specific applications, petrol forecourts are undoubtedly one of the key battlegrounds for ANPR. The need to identify offending vehicles and their owners has been brought into sharp focus by the losses suffered by forecourt retailers in Britain. Although these are estimated to have fallen by eight per cent in 2008, to £29.9 million, according to BOSS - the British Oil Security Syndicate, there is no room for complacency. Crucially, 88% of these losses came from customers driving off without paying or claiming to have no means of payment. To tackle the problem a growing proportion of forecourts now have an ANPR capability integrated into their existing security measures, the police too are taking active steps to deal with the issue. Warwickshire Police, for example, as part of ‘Operation Crunch' last December successfully deployed mobile ANPR equipment to petrol forecourts to target motorists driving-off without paying for their fuel.
A perennial issue with ANPR technology, whatever the application, is how to deal with ambient light from a scene - such as that caused by headlight glare. One approach is to utilise specialised semiconductors built-in to an ANPR camera or DVR and light from an Infra Red (IR) LED array, the result is that ambient light can be removed through processing leaving only objects which strongly reflect IR, specifically, the all important licence plate.
So to conclude, with advances in technology, ANPR is becoming an ever more valuable, and realistic, security and risk control measure for a growing number of commercial and public sector sites across the UK.