Slashdot Mirror

Depending on the laws in your state there may be various options. Most if not all ALPRs (automated license plate readers) operate in the IR spectrum which is why a lot of states have recently redesigned their plates so that they are very high contrast in the IR spectrum. This becomes important in determining how to defeat them within the law. Do some states still allow license plate covers? If so and you happen to be in one get one that is opaque in the IR, or use a clear paint that is IR opaque. Now if you don't live in a state where covers are legal you have a harder time. About the only thing you could do (again depending on vehicle illumination laws) is flood out lots of IR near the plate and horribly throw off the metering. By lots I mean like 100s of watts as you want it to be like taking a picture of the sun and push the auto exposure so far out of wack that it darkens everything else. If someone wants some info on what others have tried here is one guy who tried to get the flaring effect but was only working with a few watts of power. Again he might of had better success if he went up to 100s of watts, but still I think the best bet would be to go for throwing the exposure off.

100s of watts isn't really anything when your car is running but will quickly drain your batter when off so there you would either have to go without or plug the thing in.

Depending on the laws in your state there may be various options. Most if not all ALPRs (automated license plate readers) operate in the IR spectrum which is why a lot of states have recently redesigned their plates so that they are very high contrast in the IR spectrum. This becomes important in determining how to defeat them within the law. Do some states still allow license plate covers? If so and you happen to be in one get one that is opaque in the IR, or use a clear paint that is IR opaque. Now if you don't live in a state where covers are legal you have a harder time. About the only thing you could do (again depending on vehicle illumination laws) is flood out lots of IR near the plate and horribly throw off the metering. By lots I mean like 100s of watts as you want it to be like taking a picture of the sun and push the auto exposure so far out of wack that it darkens everything else. If someone wants some info on what others have tried here is one guy who tried to get the flaring effect but was only working with a few watts of power. Again he might of had better success if he went up to 100s of watts, but still I think the best bet would be to go for throwing the exposure off.

100s of watts isn't really anything when your car is running but will quickly drain your batter when off so there you would either have to go without or plug the thing in.

Yes I do. When I first wondered if it would be possible to do such a thing I did some searching and found the following 2 posts from someone who had puttered around with it some:
post 1
post 2
My takeaway from that is that he was gong for more of a flare effect which he did sort of achieve but only with modifying the plate which would likely result in other legal issues. In the tests he did he was still operating in the 10s of watts range which isn't that much power. Instead my thought would be to throw the exposure off of the camera and massively underexpose the plate. To do this you would need to have a draw in the 100s of watts and have it be over a larger area near the plate. Also the LEDs to use looks to be these ones. Working in IR also has the advantage that many states have resigned their license plates so that they are easier to read in the IR spectrum as the cameras used for ALPRs are IR cameras. Also keep in mind that covering your license plate with anything may be illegal in your state as it is in Minnesota and that there may be vehicle illumination laws which apply but that doesn't appear to be the case in MN as they only cover visible light. But from what I can tell pumping out half a KW of IR in front of and behind your car in MN isn't illegal (IANAL) so long as the device doing it doesn't cover the license plate.

Yes I do. When I first wondered if it would be possible to do such a thing I did some searching and found the following 2 posts from someone who had puttered around with it some:
post 1
post 2
My takeaway from that is that he was gong for more of a flare effect which he did sort of achieve but only with modifying the plate which would likely result in other legal issues. In the tests he did he was still operating in the 10s of watts range which isn't that much power. Instead my thought would be to throw the exposure off of the camera and massively underexpose the plate. To do this you would need to have a draw in the 100s of watts and have it be over a larger area near the plate. Also the LEDs to use looks to be these ones. Working in IR also has the advantage that many states have resigned their license plates so that they are easier to read in the IR spectrum as the cameras used for ALPRs are IR cameras. Also keep in mind that covering your license plate with anything may be illegal in your state as it is in Minnesota and that there may be vehicle illumination laws which apply but that doesn't appear to be the case in MN as they only cover visible light. But from what I can tell pumping out half a KW of IR in front of and behind your car in MN isn't illegal (IANAL) so long as the device doing it doesn't cover the license plate.

I've thought about doing a similar thing to this to defeat ALPRs but it seems that most of these methods don't take it far enough. most of them are trying to get some bleed into the surrounding area of the sensor. A few watts of power draw is nothing which is what most of these attempts do, I'm thinking like 100W power draw for each license plate. I'm looking for this effect but in the IR. So instead of trying to create lens flare I want to massively underexpose the image. In this case I may also get some massive lens flare as well but that isn't what I would have been shooting for. Also using some LEDs like these would be good as they are far enough into the IR that they don't have the red glow that others do.

Might I suggest lots of high output IR LEDs in a hat maybe. To do a dazzle effect is hard but screwing up the exposure is easier if you can have an abnormally bright area. I have wanted to do somehting like that to automated license plate readers (ALPR) and some people have played around with that idea but they were trying to dazzle the reader where I want a larger area of high output LEDs to throw off the exposure, like a couple hundred watts of IR LED light.

All plates must be (1) securely fastened so as to prevent them from swinging, (2) displayed horizontally with the identifying numbers and letters facing outward from the vehicle, and (3) mounted in the upright position. The person driving the motor vehicle shall keep the plate legible and unobstructed and free from grease, dust, or other blurring material so that the lettering is plainly visible at all times. It is unlawful to cover any assigned letters and numbers or the name of the state of origin of a license plate with any material whatever, including any clear or colorless material that affects the plate's visibility or reflectivity.

So this makes it illegal to use the most effective method of stopping these things. Also it makes almost all of those vanity license plate holders illegal so consider that as it just gives them an excuse to pull you over. The other popular method of attempting to defeat ALPRs seems to be to use a few high output IR LEDs in attempt to dazzle the sensor by flooding surrounding pixels but in those don't seem to work all that well. Others have tried to flash IR LEDs but this may also be illegal in your state as it is in mine as there are usually laws governing flashing lights in motion.

My take would be instead to pump out enough IR over a large enough are to mess with the camera's exposure. Bye enough IR over a large enough of an area I am thinking of a few hundred watts over an area slightly larger than the license plate immediately surrounding it, but not covering the plate at all. From what I can tell this hasn't been attempted, but now we are talking real bright as the sun levels of power and that should screw up the metering on the camera. For LEDs I am thinking these as they appear to be about as high efficiency as I can find that put out a lot of IR.

Looks like the problem may just be not enough power.

Looks like the problem may just be not enough power.

I have thought of building an LED license plate frame to mess with the cameras and others have tinkered with the idea some. The results at best could be considered hit or miss but that doesn't mean it couldn't be improved upon since most I have seen only output a few watts of power. I have been trying to figure out if I could build one with a power draw of 100-200W using some high output IR LEDs (the new license plates Minnesota uses are designed to be highly viable in the IR spectrum). Having a frame that isn't covering the license plate at all is perfectly legal in Minnesota but other things are not Minnesota statute 169.79 Subd. 7. Also the existing laws on vehicle illumination would also not prohibit this.

By frame I mean many concentric rings of LEDs packed tightly around the license plate so that you have 100 watts of IR LEDs shining around each plate. One of these days I will get some time to do it, and may also look into illuminating the front and rear windshield with IR LEDs as well in a similar fashion to further flood the image with IR.

I have thought of building an LED license plate frame to mess with the cameras and others have tinkered with the idea some. The results at best could be considered hit or miss but that doesn't mean it couldn't be improved upon since most I have seen only output a few watts of power. I have been trying to figure out if I could build one with a power draw of 100-200W using some high output IR LEDs (the new license plates Minnesota uses are designed to be highly viable in the IR spectrum). Having a frame that isn't covering the license plate at all is perfectly legal in Minnesota but other things are not Minnesota statute 169.79 Subd. 7. Also the existing laws on vehicle illumination would also not prohibit this.

By frame I mean many concentric rings of LEDs packed tightly around the license plate so that you have 100 watts of IR LEDs shining around each plate. One of these days I will get some time to do it, and may also look into illuminating the front and rear windshield with IR LEDs as well in a similar fashion to further flood the image with IR.