How License Plate Recognition Works

LPR camera system
License plate recognition (LPR) is a technology that has a number of useful applications. From helping police track down wanted criminals to making sure drivers pay tolls or are issued tickets for infractions, there are plenty of ways in which this technology can help law enforcement out on the roads. Of course, the technology that has to be in place to read and analyze a license plate is quite impressive, as vehicles regularly move along at high rates of speeds and come in all different shapes and sizes. To be able to read any license plate on any vehicle that happens to come along, license plate recognition technology has to be highly advanced and refined.

It All Starts with a Camera

To read license plates, it is necessary to start with a great camera. The camera needs to be able to capture a clear image of the identifying marks on a license plate if it is going to serve its purpose, so high-resolution is a must. Also, the camera must be positioned at an angle that provides the opportunity to clearly see vehicles from behind. Thanks to the many recent advancements in digital camera technology, it is now possible to deploy LPR systems in a variety of applications for a reasonable price.

Divided Into Lanes

Just as is the case on the road itself, cameras are divided up into lanes in order to monitor traffic. Usually, systems will have a dedicated camera for each lane in order to be able to keep track of everything that is happening from one side of the roadway to the other. However, if a system is using a modern camera with high-resolution capability, that camera may be able to keep track of all lanes of traffic at the same time all on its own.

Finding the Plate

One an image of a vehicle is available, it is then up to the computer to ‘make sense’ of the image in order to begin the process of reading the plate. There are extremely complicated algorithms used to handle this task, which is made up of several steps. The first step that must be completed is determining exactly which part of the car is the license plate. That might be an easy job for human eyes, but it is more difficult for a computer. Also, once the plate is found and sized appropriately, it must then be ‘normalized’ to permit the algorithm to continue on toward the eventual goal of identifying the vehicle in question.

Reading the Plate

Finally, after the camera has done its job and the computer has located the plate itself, the system will move on to breaking up the various characters represented on the plate in order to get the final plate number. Once the characters have been read and recorded, the computer can sort through its database of vehicle records in order to complete the process.

License plate recognition systems are only going to continue to improve in their ability to identify cars as they travel down the road. This will be a great thing for a variety of reasons, from catching criminals to collecting traffic tickets and more. Thanks to impressive technology and creative engineering, drivers attempting to get around the law will have nowhere to hide.

Posted in License Plate Recognition
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