Highly reflective UK rear number plates

[junglejim42 0]

Here in the UK all vehicles have reflective yellow rear number plates.

 

Using an Avtech 760 and Pecan 520TVL hi res 1/3 ccd B/W cameras (great during the day) all I get at night is white out for the number plate due to the reflectiveness.

 

Any suggestions how to over come this would be welcomed

 

 

many thanks

[blake 0]

Looks like IR is the problem.Does your camera have ir?

[junglejim42 0]

Looks like IR is the problem.Does your camera have ir?

Not any more. IR made things worse. Just street lighting

[blake 0]

Hmm i wonder if they coated their plate with something like photo blocker that makes the plate unreadable by things like red light cameras.That stuff makes the whole plate wash out white.It would make sense since they are thieves

[blake 0]

Do you have a way of mounting a camera at plate height so that the camera would have more of a direct view rather than looking down.If i remember correctly,that photo blocker stuff doesn't allow angle camera shots,but it does allow straight on plate reading and shots to sorta hide that fact that it's present,since most law enforcment cameras are placed at an angle to the road surface to allow plate recognition from the side along with a picture of you.

[junglejim42 0]

Do you have a way of mounting a camera at plate height so that the camera would have more of a direct view rather than looking down.If i remember correctly,that photo blocker stuff doesn't allow angle camera shots,but it does allow straight on plate reading and shots to sorta hide that fact that it's present,since most law enforcment cameras are placed at an angle to the road surface to allow plate recognition from the side along with a picture of you.

they cannot be mounted any different without them being in easy reach for the scroats to rip them down

[blake 0]

What about changing your mounting angle so that the camera or cameras are looking at your vehicle at an angle from the front and an angle from the rear.So say you mount a camera more toward the rear of your vehicle looking forward,and a more forward camera looking toward the rear.That would give your camera a more direct angle shot of the license plate rather than trying to catch it from more of a side view.

[Kiwi 0]

I think plates in many parts of the world are like this. The reflective material is diffuse so angle should not be so much of an issue. It's the huge amount of IR from the incandescent motorcycle-style combo tail and brake light that is the problem. The street light is probably sodium or mercury, pretty minimal in IR I would assume. The camera is more sensitive to the IR than the human eye so that's why it's washed out in the plate area on video.

 

A more extreme IR filter may help, as might a wide dynamic range camera, but since the brightness is localized auto exposure will still try to adjust for the entire scene and keep the plate washed out.

 

A solution might be to add a second, parallel daylight color camera on the same scene which would be better suited for that level of light.

[CameraGimp 0]

The problem you have got is the camera is allowing the highlights to clip.

 

Cameras are dumb, they don't know what it is in the scene that you want to see so they makes some best guesses. In this situation it is viewing a darkish scene with some small highlights (the number plate) the camera has to make a choice, bring the large area up (by applying AGC) or expose the small highlights at the detriment of the low lights. Most cameras will bring the dark areas up and clip highlights, CCTV cameras should see at low light.

 

You might try a video auto iris lens and adjust the pk/av to pk or turn AGC off (but that will make things darker).

[junglejim42 0]

Test using an Sony HAD 1/3 NSTC IR camera and reflective number/licence plate

 

Picture 1 before,

picture 2 finger just placed over the edge of the lense, unfortunately unable to stand there all night

 

[CameraGimp 0]

I'd say that your finger is being seen by the camera as a large bright object, so the camera isn't applying a lot of gain and so the number plate isn't clipped.

 

 

In the scene without your finger the number plate is a smaller portion of the scene but the brightest part. The camera applies gain so you see the dark areas but allows the highlights to clip so you can't see the number plate.

 

Try bringing the number plate closer. It'll probably do the same thing as your finger if you get it close enough.

[ak357 0]

I'd say that your finger is being seen by the camera as a large bright object, so the camera isn't applying a lot of gain and so the number plate isn't clipped.

 

 

In the scene without your finger the number plate is a smaller portion of the scene but the brightest part. The camera applies gain so you see the dark areas but allows the highlights to clip so you can't see the number plate.

 

Try bringing the number plate closer. It'll probably do the same thing as your finger if you get it close enough.

 

or if u have option in camera settings "negative" try it

 

[Kifertech 0]

here we have bro said negative camera, special used for licence plate like car park entrance and exit.

 

can not use IR camera for this, that plate reflect lights.

[ak357 0]

here we have bro said negative camera, special used for licence plate like car park entrance and exit.

 

can not use IR camera for this, that plate reflect lights.

 

The pix above is under IR and "negative"