To get optimal ANPR and recognition results a couple of factors need to be taken into account.

Follow the steps below to get optimal results.

 

 

1.Optimisation starts with a good projection.
The chapter positioning of the Gatekeeper-X is essential for license plate recognition. A good recognition starts with a proper camera projection.
 

2.Country specific syntax
As of March 2023 with the launch of our new ANPR engine this step is no longer required. Gatekeepers ordered after this date automatically come with the new engine.
Set country specific syntax by choosing country modules in all ANPRAxons, read more.

 

3.ANPR inspection tool
The tool visualizes ANPR and is used during installation for camera positioning and adjustment of camera settings to get an optimal ANPR result.
It displays the width and height of the license plate (recommended width between 100-300 pixels), the sharpness and the brightness.
 

4.Set  zoom, focus, exposure and iris
Start with setting zoom and focus.
Continue with the exposure and iris.
 

5.Setting two sequences of the IR sensitive sensor
To maintain optimal license plate recognition in various lighting and weather conditions we strongly recommend using sequencing.
Sequencing divides the video stream in two separately adjustable streams.
 

6.Increase frame rate and select region of interest of the ANPR sensor
Selecting region(s) of interests speeds up ANPR and classification tasks enormously.
Region of interest this minimizes the amount of pixels and the amount of random background that needs to be analysed. It will improve performance and increase framerate.

 

7.Set the proper threshold for ANPR
Setting the ANPR threshold defines the number of equal recognitions of a lp before it is considered an approved recognition result.
The higher the threshold the more certain the reading is accurate. It is used to capture license plates that are difficult to read even for the human eye.
When the threshold is set to 4, a license plate has to be recognized 4 times before it is approved.
 

8.Setting minimal license plate width
The recommended width of a license plate is between 100-300 pixels. Depending on the mounting position and the cropped region of interest, a license plate can be too small when it enters the scope of a sensor.
Setting the minimal width will prevent the ANPR engine to read license plates that are too small.
 

9.Optional: add the VideoSourceAxon (color camera) to the ANPR engine
As of the Gatekeeper-X3 the second camera serves as a source for ANPR by default; This step is no longer necessary.
 
For optimal recognition it is possible to add the images of the color sensor to the recognition process.