People normally do this by scanning a 10mW 832nm laser with a mirror, according to Dan Gelbart in https://www.youtube.com/watch?v=0MtRxX0crjU. The lecture is 77 minutes, covering nonlinear junction detectors, digital calipers, the US-embassy bug in Russia, laser microphones bounced off windows, and geometric errors from material relaxation. The bit about camera detectors is close to the end. Works for eyeballs too.
Lensless sensors (for example, using compressed sensing, or Hadamard shadow masks) can presumably defeat this, but also, watching from far enough away should defeat it. Hard to do that inside a pervert's AirBNB, though.
The junction detector is a truly brilliant idea that, unfortunately, is probably rendered nearly useless now that everything in the world has embedded electronics in it.
Also, thinking about it, you could probably defeat the optical retroreflection detector by putting the camera behind a Faraday rotator (optical isolator). But those are quite expensive and you'd need to be really paranoid to use one, plus it'll only really work well if you match the wavelength of the laser.
> though would never get the finger cause Im not a creep.
Wearing them out in public is definitely enough to get the finger and be called a creep, because many people think they're always recording. I think you're underestimating the hatred of modern tech.
Until someone develops hidden cameras with AI that will be auto turned on couple of hours later after detecting presence at that time a scan was already performed and nothing was found.....
this works by looking at the physical characteristics of the lens, so on or off should work regardless, you could have something with some kind of internal shutter to cover the lens maybe
But then you would need an IR camera instead of using the phone's camera. An IR camera should be able to find some hidden cameras passively by detecting a heat source.
There are SWIR, MWIR, and LWIR cameras among IR cameras. SW is just regular camera with the filter removed and they can't see heat. Somewhere between SWIR and MWIR are uncooled IR cameras that use MEMS heat sensor ish arrays built on top of a camera sensor that can actually see heat by differentiating between previous and current frames, with the caveat that they cannot do it indefinitely but must use a mechanical shutter to periodically cool down to operational conditions.
MWIR and LWIR cameras are often cooled and uses more exotic sensing mechanisms, sometimes even vacuum tube based, nowadays usually semiconductor based but not regular CMOS. Some require mechanical shutters obscuring view every other frame(that, I think, is where BHOT/WHOT switch came from; it must be switching whether to show odd or even frames).
You need the MEMS types or better to see heat; they're more often referred to as thermal cameras than IR cameras. They are also unable to see through regular soda-lime glasses, that might pose its own challenge as well.
not really, no. It'll happily show you IR (just point it at your remote control with the camera active, and press some buttons. Enjoy the light show on your screen that your eyes don't see).
Yes and no. The IR filter is pretty strong. If you have an intense IR source, then it overwhelms the filter, but it would blow out the sensor, without it. The sensor is biased towards IR.
I've converted cameras (DSLRs) to IR, and you use a replacement IR-pass filter. The IR-blocking (default) filter looks like a piece of blue glass. The IR-pass filter looks like a piece of black glass.
NOTE: It's not perfect. The DSLR image processors and calibration systems are calibrated to the IR-blocking filter. Stuff doesn't work the same, once you convert.
It sees it poorly. IR is deliberately (though imperfectly) filtered in the optical path.
The dim purpleish glow from a remote that is seen through [many] digital cameras would be quite bright if this IR filter weren't in place.
It doesn't have to be that way, but it usually is that way anyway -- as a design intent.
Cameras used for surveillance, meanwhile, often lack these filters. They're designed with more of a focus on getting any kind of image at all, including when working with infrared illuminators in the absence of visible light. Some even have mechanical elements that move filters out of the optical path for night mode.
This differs tremendously in comparison to a camera that is designed to produce very beautiful visible-light photographs.
(This all conspires to mean that IR is kind of a non-starter for this sort of cell phone camera hack.)
That was true years ago, but I haven't been able to use an iPhone camera to pick up an IR signal in a long time. Just tested it to be sure they hadn't reverted to an unfiltered lens (17 pro) and nope, no IR visible.
I pointed at the remote of my fan and I can see it. I am on 15 Pro. However, as the sibling comment said, it is very faint so I'd guess not very realistic.
Depends on how cheap you go - most of the cheap ones that take images where the blacks look grey likely do not have an IR filter on them. Most quality phones will use a camera with IR filters on them - blacks look like blacks.
Perhaps to avoid tipping off the entity recording you by blasting their hidden cameras with bright lights. Granted, the PoC device in the article is not exactly subtly looking, but if you could turn it into a sleek device it would be more useful. Not playing your hand while you're under surveillance lets you control the information they're receiving.
Though the bigger issue with my theory is that while most cell phone and webcam devices have IR filters, many surveillance cameras intentionally do not.
If you're being surveilled in a way that you don't want to tip the observers is one thing, but if you're in an AirBnB type place, fuck 'em. I'd even be fine with running some lasers in the place that ruins the sensor.
That's actually much easier to detect, any camera without an IR filter would show an LED emitting where your eyes did not, no complicated solution necessary.
Another strategy that's often used is to cause motion then detect the resulting transmission spike. That's also defeatable of course (cache+burst, CBR, etc).
The ideal detector should incorporate multiple methods. Someone should make a site that rates these for each detection method then adds them into an overall score.
For now, but there's really no point in detecting them anyway, since there are plenty of truly concealed options for those that really want to be pervs.
Strongly disagree. Most crimes are crimes of opportunity. Most 'pervs' don't start out that way either. Detecting increasingly easy to conceal sousveillance devices is probably essential for any kind of normative public sphere to continue to exist.
this is an old trick and works with any digital camera units. the flash reflects on the silicon behind lens or something. the operator is normally supposed to look across the area of interest through a special glass like a witch doctor to spot cameras using their skill and training, rather than letting an AI do the fun part.
Can't a thermal camera can do this? It should be able to detect any difference in ambient temp, even a few degrees, and a CMOS sensor gets warm, not to mention any wireless transmitters, power sources, and ICs. Turn off everything in the room and walk around with a ~$100 ali express handheld thermal camera.
LED clocks, alarm motion sensors, bluetooth speakers and whatever other appliances also get a bit warm. How would you tell a legit device from one with a milliwatt camera?
Yeah I don’t think this will be effective, cameras can be put in certain angles that it can see with being seen, or how police do it, entirely behind clothes or similar fabric where it can see through and identify but not seen even if you’re looking straight at it.
53 comments:
People normally do this by scanning a 10mW 832nm laser with a mirror, according to Dan Gelbart in https://www.youtube.com/watch?v=0MtRxX0crjU. The lecture is 77 minutes, covering nonlinear junction detectors, digital calipers, the US-embassy bug in Russia, laser microphones bounced off windows, and geometric errors from material relaxation. The bit about camera detectors is close to the end. Works for eyeballs too.
Lensless sensors (for example, using compressed sensing, or Hadamard shadow masks) can presumably defeat this, but also, watching from far enough away should defeat it. Hard to do that inside a pervert's AirBNB, though.
The junction detector is a truly brilliant idea that, unfortunately, is probably rendered nearly useless now that everything in the world has embedded electronics in it.
Also, thinking about it, you could probably defeat the optical retroreflection detector by putting the camera behind a Faraday rotator (optical isolator). But those are quite expensive and you'd need to be really paranoid to use one, plus it'll only really work well if you match the wavelength of the laser.
For Meta they need to detect people giving wearers the finger to stop the glasses from recording or taking pics ha
I do wear my Metas frequently though would never get the finger cause Im not a creep.
Our culture has definitely changed from when Google Glass wearers were referred to as Glassholes.
It appears that more people have just accepted that they will be filmed anywhere and everywhere.
I miss the old days.
We went from opt-in zones to opt-out zones. Living spaces with curtains drawn and the inside of your vehicle should really be opt-in though.
> though would never get the finger cause Im not a creep.
Wearing them out in public is definitely enough to get the finger and be called a creep, because many people think they're always recording. I think you're underestimating the hatred of modern tech.
Finally, a practical use for those notification LEDs. Definitely adding this to my travel toolkit if it proves reliable.
Until someone develops hidden cameras with AI that will be auto turned on couple of hours later after detecting presence at that time a scan was already performed and nothing was found.....
this works by looking at the physical characteristics of the lens, so on or off should work regardless, you could have something with some kind of internal shutter to cover the lens maybe
Using the phone's existing LED for this is clever. Wonder if the 'AI' is genuinely learning or just a sophisticated reflection analysis.
Wonder if it handles the really tiny pinholes effectively. For now, a thermal camera feels more robust for peace of mind.
This detects cameras that are off, which a thermal camera would not.
If this worked with IR, and so non visible, it might be even more useful.
Great idea though.
Walk around your neighborhood and see who has security cameras.
Security camera through PVS14 https://youtu.be/gEWniEhtE2k
But then you would need an IR camera instead of using the phone's camera. An IR camera should be able to find some hidden cameras passively by detecting a heat source.
There are SWIR, MWIR, and LWIR cameras among IR cameras. SW is just regular camera with the filter removed and they can't see heat. Somewhere between SWIR and MWIR are uncooled IR cameras that use MEMS heat sensor ish arrays built on top of a camera sensor that can actually see heat by differentiating between previous and current frames, with the caveat that they cannot do it indefinitely but must use a mechanical shutter to periodically cool down to operational conditions.
MWIR and LWIR cameras are often cooled and uses more exotic sensing mechanisms, sometimes even vacuum tube based, nowadays usually semiconductor based but not regular CMOS. Some require mechanical shutters obscuring view every other frame(that, I think, is where BHOT/WHOT switch came from; it must be switching whether to show odd or even frames).
You need the MEMS types or better to see heat; they're more often referred to as thermal cameras than IR cameras. They are also unable to see through regular soda-lime glasses, that might pose its own challenge as well.
Can’t phone cameras pick up IR?
the raw sensor can, but there's usually an IR blocking filter in the lens assembly.
not really, no. It'll happily show you IR (just point it at your remote control with the camera active, and press some buttons. Enjoy the light show on your screen that your eyes don't see).
Yes and no. The IR filter is pretty strong. If you have an intense IR source, then it overwhelms the filter, but it would blow out the sensor, without it. The sensor is biased towards IR.
I've converted cameras (DSLRs) to IR, and you use a replacement IR-pass filter. The IR-blocking (default) filter looks like a piece of blue glass. The IR-pass filter looks like a piece of black glass.
NOTE: It's not perfect. The DSLR image processors and calibration systems are calibrated to the IR-blocking filter. Stuff doesn't work the same, once you convert.
I did that with a cheap webcam years ago. All my black hoodies were white, and so were the leaves on trees.
Yup. IR images are cool. Snowscapes in the summer.
Cheap cameras are best, as they don't have too much precalibrated stuff.
I converted a Nikon D70s, and it still works great.
I’d think so. My iPhone can see my remote’s IR.
It sees it poorly. IR is deliberately (though imperfectly) filtered in the optical path.
The dim purpleish glow from a remote that is seen through [many] digital cameras would be quite bright if this IR filter weren't in place.
It doesn't have to be that way, but it usually is that way anyway -- as a design intent.
Cameras used for surveillance, meanwhile, often lack these filters. They're designed with more of a focus on getting any kind of image at all, including when working with infrared illuminators in the absence of visible light. Some even have mechanical elements that move filters out of the optical path for night mode.
This differs tremendously in comparison to a camera that is designed to produce very beautiful visible-light photographs.
(This all conspires to mean that IR is kind of a non-starter for this sort of cell phone camera hack.)
Ah ok that makes sense. I just pointed at my remote and it is very very dim.
That was true years ago, but I haven't been able to use an iPhone camera to pick up an IR signal in a long time. Just tested it to be sure they hadn't reverted to an unfiltered lens (17 pro) and nope, no IR visible.
I pointed at the remote of my fan and I can see it. I am on 15 Pro. However, as the sibling comment said, it is very faint so I'd guess not very realistic.
Try the selfie (aka front-facing) camera; often they are not equipped with an IR filter.
Depends on how cheap you go - most of the cheap ones that take images where the blacks look grey likely do not have an IR filter on them. Most quality phones will use a camera with IR filters on them - blacks look like blacks.
Pining for the days when phones had IR blasters (e.g. galaxy s6); that would work perfectly for this
some more modern phones from xiaomi still have IR blasters
Why would that be more useful?
Perhaps to avoid tipping off the entity recording you by blasting their hidden cameras with bright lights. Granted, the PoC device in the article is not exactly subtly looking, but if you could turn it into a sleek device it would be more useful. Not playing your hand while you're under surveillance lets you control the information they're receiving.
Though the bigger issue with my theory is that while most cell phone and webcam devices have IR filters, many surveillance cameras intentionally do not.
If you're being surveilled in a way that you don't want to tip the observers is one thing, but if you're in an AirBnB type place, fuck 'em. I'd even be fine with running some lasers in the place that ruins the sensor.
I'm an adult male so I don't care if someone wants to record my dong but this is very helpful for families with kids.
Unless the hidden camera has IR capabilities.
That's actually much easier to detect, any camera without an IR filter would show an LED emitting where your eyes did not, no complicated solution necessary.
Another strategy that's often used is to cause motion then detect the resulting transmission spike. That's also defeatable of course (cache+burst, CBR, etc).
The ideal detector should incorporate multiple methods. Someone should make a site that rates these for each detection method then adds them into an overall score.
I wonder if it works with smart glasses.
You don't need this to detect smart glasses, they're very obvious.
For now, but there's really no point in detecting them anyway, since there are plenty of truly concealed options for those that really want to be pervs.
Strongly disagree. Most crimes are crimes of opportunity. Most 'pervs' don't start out that way either. Detecting increasingly easy to conceal sousveillance devices is probably essential for any kind of normative public sphere to continue to exist.
Proctologists agree on this one thing that smart glasses can never conceal.
this is an old trick and works with any digital camera units. the flash reflects on the silicon behind lens or something. the operator is normally supposed to look across the area of interest through a special glass like a witch doctor to spot cameras using their skill and training, rather than letting an AI do the fun part.
Can't a thermal camera can do this? It should be able to detect any difference in ambient temp, even a few degrees, and a CMOS sensor gets warm, not to mention any wireless transmitters, power sources, and ICs. Turn off everything in the room and walk around with a ~$100 ali express handheld thermal camera.
LED clocks, alarm motion sensors, bluetooth speakers and whatever other appliances also get a bit warm. How would you tell a legit device from one with a milliwatt camera?
If you walk up to it and point the camera at it, you can see a lot of detail about what is going on in the device.
Here are some pictures of some ordinary electronics for reference:
* https://imgur.com/a/Sp16EfK
Cool, but we need that for microphones.
Anything can be a microphone:
https://people.csail.mit.edu/mrub/VisualMic/
It would be interesting to see if anyone can recover behind the camera audio from 4K movies.
Yeah I don’t think this will be effective, cameras can be put in certain angles that it can see with being seen, or how police do it, entirely behind clothes or similar fabric where it can see through and identify but not seen even if you’re looking straight at it.
https://en.wikipedia.org/wiki/Perfect_is_the_enemy_of_good