“Extremely accurate” number plate cameras
Posted on Wednesday, July 25th, 2007 by Home Office WatchCategory: Surveillance
Automatic Number Plate recognition gets 1 in 25 read-outs wrong, the Department for Transport reveals.
We discovered last week - thanks to an inadvertent leak from the Home Office - that the whole national network of ANPR cameras will soon be linked in to the police.
So the accuracy of the cameras is pretty vital.
And while 96% is pretty good as a mark in a maths test, it’s less good when it comes to tracking car drivers’ every movement. When you consider that the cameras monitor millions of cars, 4% failure turns into thousands upon thousands of false positives.
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July 26th, 2007 at 9:32 am
The attitude to this error rate depends on what you want to use the data for. If it is just one sighting of a vehicle that is vital to some investigation, then it is very important to be sure that the risk of the recognition being wrong is understood by all who wish to make use of the information. If it is a case that a vehicle’s movements are being tracked in a dense urban area with many cameras (as in London’s Congestion Charge zones) or along a motorway equipped with many cameras, then there are standard methods to process ‘dirty’ datasets (datasets in which some of the data is very likely to be wrong). So a little more finesse in this post about number plate recognition would have been better.