Poor IR contrast in new Tennessee license plates
- Thread starter wtimothyholman
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- Nov 25, 2016
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That's actually a pretty darned good image. Do you have some special lighting nearby? Perhaps a very bright streetlight, or exterior white lights?
Only one I've recorded up here in NY.
View attachment 135631
View attachment 135631
Theres a streetlight about 50ft to the left but this area is pitch black. Taken with a 5442 Z4E with onboard IR set at 1/1000 shutter.
richardgohth
Getting the hang of it
I have noticed the closer we can get the camera to the plate, the better chance to read at night with these new plates. I temp rigged one about 30 feet away and the results were much better.
- Nov 25, 2016
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Your results make me wish that Dahua would market a -Z12 version of the 5442 series camera. The larger sensor and improved resolution makes a big difference in readability, even with the poor contrast of the new plates.
The testing I mentioned in post #206 above with temp rig set up closer was with an older 5231R-ZE which is the same 1/2.8" sensor as the Z12E.
The ZE at 30 feet away captured the plate, but the Z12E at 175 feet did not.
Maybe a 5442 version of the Z12E would help, but I think we simply need to be closer to capture these new plates.
The ZE at 30 feet away captured the plate, but the Z12E at 175 feet did not.
Maybe a 5442 version of the Z12E would help, but I think we simply need to be closer to capture these new plates.
Swampledge
Getting comfortable
It appears to me that the reason that plate was so visible is that it is well lit by the vehicle’s (likely bright LED) license plate lights. If it had been an unlit front license plate, where IR illumination mattered, maybe not so good.
Good point! I will see if I have any that came past that didn't have plate lights!
Yeah the 5442 is much brighter than the standard 2mp and unfortunately this car didnt have a front plate
- Nov 25, 2016
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Tennessee vehicles only have rear plates. But the point about the LED plate lights is well taken. That's enough white light to account for the improved contrast.
- Nov 25, 2016
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I think it would help quite a bit. If @33696933 is getting that type of image at 45 feet with a -Z4 camera, I certainly think I could do just as well at 80 feet with a -Z12 version.
- Nov 25, 2016
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I haven't given up on finding a solution for the contrast problems in the TN plates.
My latest thoughts: keep the camera in color mode (no auto or B/W), with the IR filter remaining in place. Then use strobed white light illumination. Axton claims that their white light pulsar illuminator doesn't look particularly bright to the human eye because the flashes are too short in duration to register on the retina (20 W at 10% duty cycle).
So really nothing changes at all with the settings of the camera as you go from day to night. A person driving by will see white lights, but as far as they would know, it's just spotlights on the corners of my house. Assuming the strobed LEDs are bright enough, the plate will be readable.
I intend to do some preliminary experiments with focused LED flashlights to see if there's any hope of making this work.
My latest thoughts: keep the camera in color mode (no auto or B/W), with the IR filter remaining in place. Then use strobed white light illumination. Axton claims that their white light pulsar illuminator doesn't look particularly bright to the human eye because the flashes are too short in duration to register on the retina (20 W at 10% duty cycle).
So really nothing changes at all with the settings of the camera as you go from day to night. A person driving by will see white lights, but as far as they would know, it's just spotlights on the corners of my house. Assuming the strobed LEDs are bright enough, the plate will be readable.
I intend to do some preliminary experiments with focused LED flashlights to see if there's any hope of making this work.
Intriguing! Can't wait to see the results.
Looking at the specs, the 20W white pulsed is only good to 48 feet, so that would knock a lot of us out of it.
But the 100W would be good up to 226 feet.
I wonder what these bad boys cost? And will it really just look like a floodlight that isn't being blasted down into the drivers face lol
Looking at the specs, the 20W white pulsed is only good to 48 feet, so that would knock a lot of us out of it.
But the 100W would be good up to 226 feet.
I wonder what these bad boys cost? And will it really just look like a floodlight that isn't being blasted down into the drivers face lol
- Nov 25, 2016
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Several hundred dollars, at least. But I'm looking at a different approach. There are tactical LED flashlights available at very low cost. Some of them have strobe switches to create a flashing light. They can also be focused to a narrow beam.
The question is: can the strobe effect be modified to reduce the duty cycle and increase the frequency of the flash, either internally or externally? There are also some pulse width modulated power driver boards that might be adapted to a standard LED flashlight. So an LED flashlight that is focused to a narrow beam and strobed at maximum intensity for 1 millisecond at 100 Hz might do the trick.
MikeLud1
IPCT Contributor
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I don't know how bright these strobes are. I'll just say if I had one flashing at me at night, I'd be tempted to use our president's favorite home protection device on it.
- Nov 25, 2016
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If it is flashing at 100 Hz, it will just look like a dim white light to your eyes. The retinas of your eyes simply don’t respond that quickly to very bright, very brief flashes of light.
@EMPIRETECANDY - any word on engineering? I can only imagine what kind of market penetration you could get if you could market a camera that is sensitive to 730nm, along with 730nm IR LEDs. There appears to be a real lack of such consumer level cameras - and as more states move to these printed, white-lettered plates, the demand will only increase. Early bird gets the worm!