Need help tweaking LPR camera exposure settings

erkme73

BIT Beta Team
Nov 9, 2014
1,568
1,483
I have this camera - a Dahua IPC-HFW4431R-Z 2.7~12mm that works reasonably well on my street. However, I just installed the same camera on a neighbor's new installation, and I can't seem to get the exposure correct.

I've duplicated my settings, but on her street, cars are moving much faster, and the angle of the sun is different.

Here are the current settings:

1661787575120.png

I've played with it as low as 1/2000 and as high as 1/10,000.

The problem is that, with this sun angle, the plates are still washed out:


109 2022-08-29 10.41.34.111 AM.jpg

On plates that are more vertical, or slightly shaded, I get OK results:

109 2022-08-29 10.36.07.246 AM.jpg

Just looking for some pointers on how to tweak it to get better results in a wider range of applications.
 
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You need to play with brightness and contrast for starters. On top of that it's being handicapped by the dust coming off the road. I'll bet some vehicles will raise it in such a way that it will totally obscure any plate not matter how you adjust things.
 
Yea, that's a pretty significant handicap. In fact, that Honda may well have had an inch of dust covering the plate, and no level of tweaking (short of a pressure washer) will reveal the tag.

So brightness and contrast on the camera GUI directly, correct? I just don't want to cause issues with night clarity. But I'll give that a go.
 
Here's another one the just popped up, and you can see where the tailgate shades the plate, it's readable, but the part of the tag that is in the full sun is washed out...

109 2022-08-29 10.56.12.806 AM.jpg
 
Something else I just noticed. (Though the 4431 with a 1/3 sensor isnt the best choice for LPR)

The weeds and grass in the foreground are crisp and clear, the vehicles not so much. I think the camera is having problems focusing due to the objects in the foreground. But definitely get it off shutter priority
 
Looks like I"m screwed with the new TN license plates:


Summary: Plates suck for most IR-based LPRs. Only a few of the LEO ALPRs can play with them. We're not changing the plates to accommodate. It's up to the LEOs to buy/use the type of ALPRs that work with the new plates. The rest of you, pound sand.

Good 'ole government.
 
Here are the Day settings that I use:

1661984455404.png

All of my Picture settings are set to 50/stock.

For additional tweaking make sure that Focus & Zoom is set to Manual. Park a car at the spot and tweak unless you have enough traffic to modify it on the fly.
 
Looks like I"m screwed with the new TN license plates:


Summary: Plates suck for most IR-based LPRs. Only a few of the LEO ALPRs can play with them. We're not changing the plates to accommodate. It's up to the LEOs to buy/use the type of ALPRs that work with the new plates. The rest of you, pound sand.

Good 'ole government.

Here is the thread where it is discussed and attempts to fix it:

 
Something else I just noticed. (Though the 4431 with a 1/3 sensor isnt the best choice for LPR)
I'm temporarily using a 4431m (same sensor as 4431R-Z) on my driveway. It has been running on auto exposure. When a plate is in full sun, it reads it great. When the plate is shaded, the numbers are washed out and usually unreadable. I will play around with exposure settings to see if it helps, but I'm frankly not expecting much. I've been running a few 4431s for 5 years or so and think they are great cameras when there's good lighting. My low light and night finding with running animals is with a 2 MP starlight I can see something ran through, with a 5442 I can see what it was, with the 4431 it didn't exist.
 
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Here is the thread where it is discussed and attempts to fix it:

Thanks for the link. Looks like you guys were on top of this 6 months before I caught wind. I thought I'd read the thread before making dinner... 11 pages, not gonna happen right now. Gonna save that for some "me time" later.
 
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