LPR Camera Installation tips
It is recommended to install the camera in the center of the vehicle
![](../../__attachments/2064384178/1.jpg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
If the camera is installed on the side of the road or lane, the angle should not exceed 30 degrees.
![](../../__attachments/2064384178/2.jpg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
The camera should be installed higher than the vehicle headlights so that the vehicle’s headlights don’t point directly at the camera
![](../../__attachments/2064384178/3.jpg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
Ensure the license plate width is at least 120 pixels and height at least 50 pixels
![](../../__attachments/2064384178/att_1_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
Height at least 50 pixels
Width at least 120 pixels
License plate tilt angle must be within +/- 10 degrees
![](../../__attachments/2064384178/att_2_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
![](../../__attachments/2064384178/att_3_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
LPR settings in the System Manager application
Ensure the correct region (Americas / Eurasia) is selected.
Setting the region of interest
Region of interest is used to define where detection will find license plates.
![](../../__attachments/2064384178/att_14_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
Leave some margin to the region of interest to not detect partially visible plates.
![](../../__attachments/2064384178/att_15_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
The whole license plate is inside the region of interest, and the plate is detected.
![](../../__attachments/2064384178/att_16_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
The license plate is not completely inside the region of interest, and the plate is not detected.
Enabling country recognition
In many countries letter O is similar to the number 0, and the letter I looks the same as the number 1. Enabling country detection improves detection accuracy in these cases.
![](../../__attachments/2064384178/att_4_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
For example, the format for Brazil plate number is “abc1d23”.
Common problems and solutions
Incomplete license plate
![](../../__attachments/2064384178/att_5_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
Solution: Don’t set the region of interest too close to image borders.
View angle makes plate numbers unreadable
![](../../__attachments/2064384178/att_6_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
Solution 1: Move the camera to a better place.
Solution 2: Set the region of interest so that the plate is detected when it is visible from better angle.
Other vehicles headlights reflect from license plate
![](../../__attachments/2064384178/att_7_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
Solution 1: Move the camera to a better place.
Solution 2: Set the region of interest so that the plate is detected when other vehicles’ headlights don’t point to the license plate direction.
The license plate is too small
![](../../__attachments/2064384178/att_8_for_2037187729.png?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
Solution 1: Move the camera to a better place or zoom in.
Solution 2: Set the region of interest so that the plate is detected when the vehicle is nearer to the camera.
Solution 3: Increase the minimum plate height value in LPR settings so that small plate detections are ignored.
The license plate is blurry
![](../../__attachments/2064384178/att_9_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
Solution 1: Adjust sharpness and increase shutter speed in the camera’s settings.
Solution 2: Increase the lighting of the area.
The license plate is overexposed
![](../../__attachments/2064384178/att_10_for_2037187729.jpeg?inst-v=86834bbb-50d8-440d-9b6f-3431ba4b14c8)
Solution 1: Adjust camera’s image settings.
Solution 2: Check the camera installation location and move it higher so that headlights doesn’t reflect from the plate.