License Plate Recognition

Access control using license plate recognition

License plate recognition is based on image processing methods. The live images of a video camera are evaluated using complex algorithms according to license plate information. This powerful OCR text recognition (Optical Character Recognition) enables the evaluation of license plates in real time.

The data obtained can be used for a wide variety of applications: Access controls, adding costs, generating alarms and much more.

License plate recognition thus actively contributes to increasing daily efficiency, service levels or security. Depending on requirements, the recognition software can run directly on the camera or on a powerful server that manages all license plate recognition and triggers corresponding actions in the security network. The choice is yours.

Automatic recognition and actions

OCR (Optical Character Recognition)

Everything begins with a high-resolution image of the vehicle, which is made available to the license plate recognition system. When selecting the image section or camera position, care should be taken to ensure that the scenery is well illuminated. Possible interfering factors such as vehicles on a secondary lane can be excluded from the detection.

Step 1 :
Real-time image analysis

The software analyzes the image and tries to find out where the license plate is located.

The primary goal is to reduce the amount of data to be analyzed to the few bytes that make up the number plate string in the ANSI/ASCII character space.

Step 2:
Finding the license plate

To minimize error detection, the exact location of the license plate on the image is defined.

This reduces the amount of data and increases the reliability of character recognition.

Step 3 :
Separating the characters

A first rough recognition of the characters isolates so-called pixel matrices. These enable an effective conversion into the respective ANSI/ASCII value and the programmatic further processing of the recognized number plate.

Triggering

Triggering is the mechanism that triggers image acquisition. Good video systems deliver 25 frames per second. The demands on the license plate recognition system increase with the underlying image resolution. The higher the resolution, the more difficult it is to ensure real-time recognition. The additional evaluation of the individual images using text recognition (OCR) leads to further utilization of the system.

To reduce system load, modern license plate recognition systems rely on external triggers that trigger the recognition process. These include inductive ground loops, light barriers or impulses from external systems. Ideally, however, the motion detection of a camera should be used.

In the project environment, the local conditions decide which trigger is best suited.

Recognition Rate

First of all: We cannot promise you 100% recognition.

The recognition rate of a license plate recognition system is influenced by many factors. Many of these factors influence each other.

Such factors include the resolution and image quality of the camera and the performance of the underlying PC hardware. Is the environment sufficiently illuminated to minimize image noise? In addition, there is the position of the IP camera(s) and the quality and performance of the network.

If all factors are optimally coordinated, very high detection rates are possible. We advise you!