Traffic & transportation

September 16, 2020

Your parking system is only as good as its ANPR engine

If you have an ANPR-based parking system, that’s great. If the ANPR is not accurate – that is even worse than having a system without ANPR.

We see and use more and more ANPR-assisted parking systems – where the technology of Automatic Number Plate Recognition is applied to identify incoming and exiting vehicles (an automated way of pay-by-plate parking).

It is absolutely great on one side, as we all know its practical advantages: how it makes the parking automated, offering a smooth drive-in experience and requiring much less manual work – both from the driver and the parking operator. So that is not a question…

ANPR software accuracy
the real license plate vs. the misrecognized number on the parking ticket

But when technology is applied in a wrong way, it can do more harm than good. A similar thing happened the other day when one of our managers parked in a Hungarian shopping mall – its parking system worked with ANPR (not by us), but its ANPR software was not accurate enough or the system was not properly calibrated: his license plate was recognized with an error: HLV-108 read instead of the real MLY-108.

Problems of inaccurate recognition

Such misrecognized plates can not only disturb the entry/exit management of a vehicle access control system, but may imply future issues as well. Just thinking out loud: what if the security staff would like to check if a given vehicle has ever been in the area? What if its time of arrival is needed… or what if, for any reason, the specific vehicle should be put on blacklist and be blocked from future entry? Does the system fail to read the plate the same way every time – or does it recognize it as a different plate in each case?

ANPR-based parking system
interface of an ANPR-based parking system

As we see, several questions and concerns come up – so the best choice is having a system with a high accuracy ANPR component. Being in the development of such technology for 30 years, we can certainly say, it is not an easy job. So let’s dive in the details and see how many factors contribute to a successful ANPR system!

Factors that take effect on ANPR accuracy rate

Of course, no matter how good an image you get of a vehicle if the ANPR software is not accurate – if it makes recognition errors or misreads characters. Also, you can have the very best ANPR engine – but if the image is too blurry, too distorted, it will not result in proper recognition.

ANPR software for parking system
if the ANPR is not accurate in the parking system, it can cause crucial issues

One thing is sure: the ANPR performance starts at the imaging… and ends at the ANPR engine itself. Let’s see those factors that contribute to successful recognition.

  • Input image quality: the image should show the vehicle and its license plate in a way that is readable for the human eye as well. The license plate should not be too small or too blurry – and the physical plate should not be too dirty or damaged. Fine-tuned ANPR software modules can still deal with part of these, but the best is when these issues are filtered out.
  • Camera installation: the camera that captures the vehicle should be set in such a position that creates a distortion-free view of the plate – the less distortion the image has, the easier is the ANPR.
  • Illumination: too dark images or photos which have low contrast difference between the plate and its characters, may make the ANPR software’s job difficult. That is why the proper ANPR cameras have built-in infrared illumination – helping imaging both in the daytime and nighttime.
  • ANPR recognition engine: when evaluating an ANPR software product, it is not only about accuracy rate. The ingredients of a good decision making are also the speed of recognition, the geographical coverage, the flexibility how the engine deals with special types, and more.

So what went wrong in the mentioned system? It is a complex question and may be a result of one or multiple of the factors above. Maybe the camera did not provide an appropriate input for the software. Maybe the software simply did not have the best OCR algorithm. Maybe it was too dark and the system did not have the required illumination. Or maybe even further reasons.
When designing a parking system, you need to minimize the possibility of errors, from every aspect: deal with the imaging, the illumination, the software – all the components that will define the final outcome.

To set a good example, let us show you some of the projects we are proud of – ANPR systems around the world, like at the Vilnius Airport, in this automated car wash system, on the Colombian highways or in these 5-star Dubai hotels.

Ways for using ANPR in your parking system

Back to the original idea – ANPR can take your parking system to the next level, if it works properly. It makes sense to use it, but how it is possible – you may wonder. Here, we explain some scenarios – ways to start using ANPR:

  • Get a ready-to-use vehicle access control system with ANPR: if you are working on a new project, looking for a complete system and do not wish to integrate components, select an end user product. These systems usually include the car access management software, the ANPR function, automatic barrier opening, users management and more – ready for your usage.
  • Add ANPR to an existing access control system: if your project already has an access control system but lacks the ANPR function, you can add it as an extra feature. This can be done the following ways:
    • Add ANPR software function: if there is already a camera that checks the entry/exit movements, you will need to integrate an ANPR function to extract the data from the images. You can find such SDKs and algorithms on the market (even free ones). You can also start using cloud-based ANPR SaaS (software-as-a-service) that may come in handy if you do not have the resources, budget or time for integration and need an instant solution (for that, let us draw your attention to our brand new cloud service – you can start a free trial up to 200 transactions here)
    • Add an integrated, smart camera: if you do not wish to connect the camera with software and fine-tune the image transfer, you can also get such cameras that have onboard intelligence with built-in ANPR function. The camera will provide the ready-to-use results to your system.
license plate recognition for access control
there are multiple ways to add ANPR to your access control system

All the mentioned products are available from us – and our experts are happy to answer your questions if you look for such technology.

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