Troubleshooting LPR

blazin912

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This is what started my hunt -- Day time "ghost plates".

I attempted to make my setup all B/W but I got that in the day.. no plate cover, no obfuscation, yes a poor angle, that was I believe 80% zoom?
 

blazin912

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It looks like an MA plate is very reflective but the letters, so they pop out under heavy IR. I think the problem in the day is that its so bright out, the entire plate is reflecting

If you're getting car but zero plate at all, I think you need much more IR. Would an external IR light work?
It may, where does the light need to be mounted? Off camera obviously but does it need to follow the same general angle to bounce back to the lens or can it be in a totally different location?
 

biggen

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I think you just need to tweak the camera settings. You have too much of the car at night. The car should be totally black.

3MA9T4W4589NVG27S28IHI7ZF665RF0U1B3BVZF0-254963574-1635910882693.jpg

Edit: Maybe I was looking at your daytime pic and not your night because I do see you have the car as black in the above post but no plate. Were you sure that car had a front plate? Are you wanting to run B/W 24/7 to avoid the focus issue? You can set a manual focus for both night and day. I've found that I get better captures of plates during the day time running color and I use B/W only at night.

Make sure you aren't a shutter range at night either. Try 1/1000 or 1/2000 fixed.
 
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blazin912

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I think you just need to tweak the camera settings. You have too much of the car at night. The car should be totally black.

View attachment 107113

Edit: Maybe I was looking at your daytime pic and not your night because I do see you have the car as black in the above post but no plate. Were you sure that car had a front plate? Are you wanting to run B/W 24/7 to avoid the focus issue? You can set a manual focus for both night and day. I've found that I get better captures of plates during the day time running color and I use B/W only at night.

Make sure you aren't a shutter range at night either. Try 1/1000 or 1/2000 fixed.
Yea, that was my car parked. I planned on trying to dial in my settings but had no coverage in the car. I don't really need to run B/W 24/7 I just noticed plates are complete white in day time with B/W. I'm running the Dahua service to adjust focus for B/W and Color automatically. My settings for the black car are above. I've added HLC back in and I'll test that tonight. Stay tuned for what a plate looks like midday...
 

biggen

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Those night settings don't look bad but I'd move the shutter to fixed and get off the range as I noted above. What is the distance?
 

blazin912

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So B/W day looks toast. Any chance of that ever working at night?



That is direct head-on at the approximate distance.. sun is coming from behind me so I'm actually blocking the direct light onto the plate. When I turn the plate at the approximate angle for a car in this setup it goes nearly all white..
 

biggen

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Something isn't right. Can you post a full shot of the scene? That crop looks super low resolution. I don't see where you posted any settings for daytime like you did night. What resolution and bitrate are you running there? Here is what mine looked like this morning after sunrise and before it flipped to color:

3MA9T4W4589NVG27S28IHI7ZF665RF0U1B3BVZF0-254963574-1635942075076.jpg

That nasty lens flair on the bottom right is because sunlight is actually hitting the lens. A minute later the camera switches over to full color:


3MA9T4W4589NVG27S28IHI7ZF665RF0U1B3BVZF0-254963574-1635942149230.jpg
 

blazin912

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From this morning around the 730am -- Night B/W settings were changed before this image to 1/1000 fixed and 70-70 gain fixed all other settings were the same from the shot of the car with just headlights. Camera was operating in "night"

For reference that same car w/ day settings in color:

 
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blazin912

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Also what I notice in your is the oranges in your florida plates are gone. Red/Orange close enough.. anything red/orange appears to vanish in B/W daylight
 

blazin912

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The taillights, license plate letters, and even registration sticker are all about the same color of red and all become light gray.. less than ideal on a white plate..
 

biggen

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Also what I notice in your is the oranges in your florida plates are gone. Red/Orange close enough.. anything red/orange appears to vanish in B/W daylight
That part may not be reflective. Here is that same plate with no sunlight illuminating - just my IR3MA9T4W4589NVG27S28IHI7ZF665RF0U1B3BVZF0-254963574-1630318366178.jpg
 
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biggen

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Here is a California plate with red lettering for the word "California". Its visible during the day but not at dawn in B/W mode with IR. I'm guessing that paint simply isn't reflective for the wording.

3MA9T4W4589NVG27S28IHI7ZF665RF0U1B3BVZF0-254963574-1630015079405.jpg3MA9T4W4589NVG27S28IHI7ZF665RF0U1B3BVZF0-254963574-1629072930084.jpg
 

blazin912

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Ok I'm going to run this test again tonight just by walking a plate outdoors. I should be able to point it directly at the camera with 100% IR..
 

biggen

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From this morning around the 730am -- Night B/W settings were changed before this image to 1/1000 fixed and 70-70 gain fixed all other settings were the same from the shot of the car with just headlights. Camera was operating in "night"

For reference that same car w/ day settings in color:

Your daytime is spot on! So that is progress.

You said your gain range is 70-70?? That needs to be 0 - 50 range. That high of a gain will wash everything out.
 

blazin912

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Your daytime is spot on! So that is progress.

You said your gain range is 70-70?? That needs to be 0 - 50 range. That high of a gain will wash everything out.
Night time gain is 70-70, daytime is 0-60
 

biggen

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Night time gain is 70-70, daytime is 0-60
^^ This may be your problem. Move to a range of 0 - 50 for B/W mode. Don't used a fixed gain. Ever. Unless you have 100% control of the illumination in a scene (i.e. movie studio). You need to always use a range.
 

biggen

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Well I was told to run fixed gain. The image with headlights and no plate was 10-50
In this thread you were told to run fixed gain??

You may just have to run full color in the day and B/W at night which is pretty "normal" I'd say. We just have to figure out why your B/W at night is bad.
 
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