Subscriber Discussion

What Camera Configuration For LPR Use?

TO
Tor Ove Rue
Sep 27, 2016

Hi I would appreciate tips for congratulating camera for LPR use.

I have a Samsung SNZ6320, 1080p 120WDR, I know the camera might not be the right choose. Its normal street lightning.

What is the best settings?

I will zoom in so the camera will see only one line about 5-7 meters wide, the max speed on the cars will be about 60 km/h

  • How high shutter speed?
  • Use only B/W?
  • WDR??

Thanks Tor O

JH
John Honovich
Sep 27, 2016
IPVM

You will need to have IR illuminators, do you have this already?

Because of the speed of cars you want to track, you will need a fast shutter speed (you'll need to test to be exact but around 1/500s is likely needed). Because of the fast shutter speed, the amount of light the camera will capture will be low (~90% less a 'normal' 1/30s shutter). Because of the low amount of light the camera will capture, supplemental light will be needed, i.e., IR illuminators. Also, because you will be using IR illuminators, the camera will need to be B/W at least at night.

See our License Plate Capture Shootout for test results at different light levels and with different shutter speeds.

VG
Vlad Georgescu
Sep 27, 2016

I would also suggest :

  • use MJPEG and not h264 or if you are forced to use h264 put a low GOP value so you will have fresh images in almost every frame
  • disable wdr (introduces artefacts)
  • with 1/500 shutter speed you might have the temptation to increase the gain. Dont. Put the gain to low value (<10) and use IR to compensate
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UM
Undisclosed Manufacturer #1
Sep 27, 2016

Here are settings one embedded lpr company recommends for these cameras:


It is also needed to set “Day & Night” to “B/W”. If the plate is properly illuminated we can set the camera
as follows:
-Min shutter speed: 1/500, (max: 1/12000)
-SSNR level: OFF
-AGC: Low


If, with the above parameters, the image is too dark then it is better to increase lighting or decrease
minimum shutter to 120:
-Min shutter speed: 1/120 (max: 1/12000)
-SSNR level: 4
-AGC: Medium

For best performance set “SSDR” to Level=1 and D-Range = wide and disable the “Sharpness” feature.

VG
Vlad Georgescu
Sep 27, 2016

i would say that putting 1/120 shutter speed for cars traveling at 120km/h will produce blurred images

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SM
Sergey Minevich
Oct 03, 2016

Dear friends.

We researched thematic of LPR and how it work. There are 2 main features:

1. IR range. Of course, only one opportunity to make LPR is operation in IR range.

2. Synchronization between IR-illuminating device and shutter. The main point of this complex is that IR-illuminating is operating in pulse mode: IR leds make a light pulse, after that this beam reaches place of license plate, reflects from LP and returns to shutter side. Exactly at this time shutter opens and closes. Shutter speed is so high, that if there is not LP in that exact place, all picture (even in daytime) is dark. Usual camera can't reach these 2 conditions: superhigh shutter speed and synchronization between IR-leds and shutter.

In any other case on the white LP all image will be white.

We solve this problem with white LED instead of IR. We are using cameras in b/w mode, but we turn off IR-LED at all. White LED spotlight can be installed in front of LP (well working at parking), or in the side of LP on the roads (to avoid problems with drivers).

But usually for roads they used special hardware and software complex as I described below. Most part of such questions ask installers for parking zone. In this case white LED really helps.

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