Computing replaces the officer's eye
Licence plates will now be detected by computer. Five young engineers have developed software that reduces errors and speeds up the processing of fines.
THE FACTS Gone are the days of decoding radar photos by eye. Licence plate reading will henceforth be handled by computer. A company of young engineers has developed software capable of recognising the characters on number plates for the cantonal police — a creation that opens up new prospects for them in the road traffic sector.
At the entrance to FiveCo, located on the EPFL science park site, two scooters stand waiting at the foot of the coat rack. Right next to them, the eyes of RoboX — one of the artificial machines that brought Expo.02 to life — catch the eye. The five companions who founded this start-up in September 2002 all come from the university's laboratories, each with their own speciality in microtechnology.
Image processing is one of their many areas of expertise. "It is very much in vogue in companies right now. But the market is not yet very crowded and there are many fields to develop," notes Mathieu Meisser. Bingo! The engineers have just completed a programme for the cantonal police, and new applications are already on the horizon.
Until now, all radar photos were examined throughout the day by an employee, who would zoom in and manually re-enter the plate number on the fine form. FiveCo's programme has considerably simplified this task. Once installed, it has been operational at the Blécherette headquarters since January.
The software works from the radar's digital image or from video footage. Using an algorithm, it can locate the plate regardless of the vehicle's position or the plate's angle. It isolates the plate and enhances its brightness, including for night-time shots taken with infrared flash, so that the number is legible.
Each character is then recognised by comparison with the standard typeface used — identical across all cantons — explains its designer Gilles Froidevaux. Thanks to this system, around 90% of licence plates can be read within a few seconds.
Eight or zero?
There remains a 10% chance of non-recognition. This occurs with, for example, stains, eroded digits, deformed plates, or the sometimes unintentional "touches" of drivers — such as a fixing bolt placed right in the middle of a zero, making it look like it could be an eight. "In all cases, the human remains better than the software and it is always the human who validates."
For now, with only 500 images having been processed, it is still too early to talk about the error margin. The software nevertheless reduces this risk and allows the officer to focus on illegible plates. The processing time between the flash and the fine should therefore be limited to two or three days. The next goal: extending plate reading to French number plates.
The field is promising. The young engineers are now working on a new way to locate bicycles, theft of which is on the rise. Contacted by a parking company, they are also exploring visual recognition of subscribers and tackling the problem of "suction-cup" cars — vehicles left abandoned for several days.
Patrick Combremont
