Smartphone LED detects hidden cameras with AI | Hacker News Reader

Smartphone LED detects hidden cameras with AI

chosun.com

284 pointsgeox84 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.

You could also put the camera behind a laser safety goggle lens that blocks the laser in question :)

Oh yeah... that's much simpler.

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.

If you sneak up to a house and peer in the windows, there might be trouble. I haven't looked at court decisions, and those'd be regional/country based, but if a house is 200M away on a hill, and you need a pair of binoculars to see in it, is there 'public nudity' if they walk around without the shades drawn?

I'd say no.

Yet conversely, it's not illegal(criminal) to use binoculars to peer. Still, you can get an injunction(civil) if it's a common thing, because then it moves into harassment. Restraining orders have been given. So then the question is, why is this a thing for your neighbour peering at your house with binoculars some of the day, but not for a camera doing the same 24x7? EG, a Ring camera pointed at your house, with sufficient resolution to act as binoculars?

I really wish 'viewing someone with a camera' remotely, was looked at more from the frame of 'is it the same as using binoculars'. EG, is there a zoom lens on the camera, or just as important, is it of sufficient high resolution that it can act as a zoom lens in software.

I'd like to see a court case push back against that.

I've found with technology, that everyone from judges to lawyers seem incapable, at the start, of considering it with an analog, uh, analogue. Almost all cameras are as binoculars today.

Your comment reminds me of the old Google Opt Out Village video from The Onion

https://m.youtube.com/watch?v=lMChO0qNbkY

Not everyone has accepted that.

Meta glasses are known as perv glasses. People are actively destroying flock cameras all over.

I think this Creepy Robert Scoble Google Glass High School Girls Recording is even creepier than his sharing naked shower selfies, because it involved subjecting teenaged girls to his classic brand of braggadocious self-aggrandizing behavior which he is so well known for, not just his own wet naked grinning body. That he lacks shame and self-awareness and still hasn't taken it down after all these years is just frosting on the cake.

Why Google Glass Will Be A Hit. The High School Girls Love Them.

https://soundcloud.com/scobleizer/why-google-glass-will-be-a...

Really, in Scoble's big head, that's what actually makes creepy surveillance technologies successful and worth all the costs and downsides: that high school girls love them??! They must really love Flock cameras then! Well at least their corrupt cop ex-boyfriends do.

https://edition.cnn.com/2026/08/26/us/flock-kentucky-police-...

https://edition.cnn.com/2026/07/26/us/flock-cameras-surveill...

Considering the shower photo, his personality, his entire career of being a shallow vapid yapping technology cheerleader and wanna-be gatekeeper who never accomplished anything himself beyond manufacturing the attention he is so starved for, and his sexual harassment scandal where he plugged his own new "LightPitch" Attention Manufacturing Startup in his horrible non-apology apology (actually a denial and counterattack) after his previous colleague Shel Israel parted ways in disgust, this "The High School Girls Love Them" recording sure didn't age well.

The aging dot-com-era digerati in his old-boys' network still circle the wagons around him, pretending none of this ever happened. (You know who you are!)

Non Apology Apology, Denial, Counterattack, and Gratuitous Startup Plug titled "No, of that I’m innocent.":

https://web.archive.org/web/20171025173150/https://scobleize...

LightPitch: Helping startups get attention: I, Robert Scoble, have a passion for products, and have spent the last 20 years helping others tell the story of their products. Now you can benefit from my experience.

https://web.archive.org/web/20171025180030/http://lightpitch...

Robert Scoble and Me (medium.com/quinnnorton)

https://medium.com/@quinnnorton/robert-scoble-and-me-9b14ee9...

https://news.ycombinator.com/item?id=15511285

Robert Scoble: I didn’t sexually harass women, as I lacked power over them. Scoble claims sexual harassment “has to do with the power position.”

https://arstechnica.com/tech-policy/2017/10/robert-scoble-i-...

Robert Scoble Blog Post Gives Crash Course in How Not to Apologize.

https://nymag.com/intelligencer/2017/10/robert-scoble-writes...

Robert Scoble doesn't know what sexual harassment is. It's not about 'making or breaking' someone's career.

https://mashable.com/article/robert-scoble-sexual-harassment

Scoble Isn’t Sorry. The famous tech blogger just showed us everything you shouldn’t do when you’re accused of sexual assault.

https://slate.com/technology/2017/10/robert-scobles-blog-pos...

Larry Page on Robert Scoble’s Google Glass stunt: ‘I really didn’t appreciate the shower photo’

https://www.theverge.com/2013/5/15/4333656/larry-page-teases...

The guy who ruined Google Glass with a shower selfie is at it again with Snapchat's Spectacles

https://www.businessinsider.com/robert-scoble-wears-snapchat...

> 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.

In my personal opinion, you're normalising technology that has overwhelmingly more benefit to creeps than to non creeps. So even if you're not a creep yourself, you are helping them.

Yeaaaah, you're not a creep, you just creep.

https://www.youtube.com/watch?v=tLPZmPaHme0

That sucks to hear, i wish you were getting shamed more frequently in public

For what taking pics when skiing, kayaking and other times when my hands aren't free and Im already wearing glasses. For taking pics of nature and taking pics of friends and family whom asked for a picture?

Let's see if Google/Samsung's upcoming smart glasses releasing Fall 2026 get as much flack as Meta who many techies hate Meta/Facebook.

I hope so!

> taking pics when skiing, kayaking and other times when my hands aren't free

GoPros are great for that. You can get one that is small enough to stay out of the way, have a more secure mount than glasses and a recording device that doesnt try to hide the fact that its a camera.

Don't forget his semi-recent shop tips and machining tricks videos: https://www.youtube.com/@dgelbart

The overall article and discussion here is detection, and all the weaknesses of detection.

At some point, the only solution will be active destruction. Someone will build something like a multi-wavelength high powered laser device to sweep the room. Arrive, setup the device near the center of the space, set the Start-Timer, leave, return in 3min confident and optical detectors are well fried. I hope it doesn't come to that, but...

The trick will be making sure that the entire room isn't also well-fried.

Well 100% accuracy always comes with a price.

Ha!! Yup. 'Tho it seems a ~5w laser rapidly scanning would be enough to fry optics without igniting furniture or draperies?

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

Tapo C125 has a built-in physical shutter. Also, every PTZ camera can just turn to face the wall, that would maybe defeat this too (not sure).

For the typical indoor WiFi cameras without battery backup, a simple way to detect them could be to turn all breakers off and on, and listen for their motors rotating on startup. Or make the room dark and listen for the click of the IR cut filter switching to night mode or back.

Next thing, hotels will use "microlens wallpaper", so the device becomes practically useless.

that would be bad for their reputation

If this worked with IR, and so non visible, it might be even more useful.

Great idea though.

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.

Can’t phone cameras pick up IR?

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.

I’d think so. My iPhone can see my remote’s IR.

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.

Try the selfie (aka front-facing) camera; often they are not equipped with an IR filter.

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.

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.

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.

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.

Most phones have no problem detecting IR up to the wavelength of the cheap leds used in 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.

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.

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.

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

LG V series is a few years old but I know some had them

The HP 48G series graphing RPN calculator had such a powerful, software-controllable IR LED with a learning remote program someone wrote that could control TVs roughly 70' / 20 m away as long as the TV had a sensitive enough IR receiver circuit. Some hijinks might've happened in the physics lecture hall but no exams or lectures were harmed.

Walk around your neighborhood and see who has security cameras.

Security camera through PVS14 https://youtu.be/gEWniEhtE2k

Are hidden cameras in hotel rooms such a concern that normal citizens need to be concerned with it?

I would assume most Airbnbs have hidden cameras, but that's just a feeling

That's a real concern in Korea.

I wonder if it works with smart glasses.

You don't need this to detect smart glasses, they're very obvious.

Proctologists agree on this one thing that smart glasses can never conceal.

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.

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.

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.

Examples ?

Definitely trying this next time I check into an Airbnb. The old flashlight trick is tedious.

Using the phone's existing LED for this is clever. Wonder if the 'AI' is genuinely learning or just a sophisticated reflection analysis.

Finally, a practical use for those notification LEDs. Definitely adding this to my travel toolkit if it proves reliable.

This is great. Hopefully this device becomes so ubiquitous that it deters anyone from putting up hidden cameras.

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

Ideally yes but in practice thermal cameras measure radiance not temperature and different materials are more or less radiant; putting a camera behind a wall blocks the signal or at least diffuses it; the resolution+SnR are not great at consumer price point; and background objects can be surprisingly warm. For example a tree at night can be about the same temperature as a wireless camera attached to that tree. So in the best case it can work to see power-inefficient devices out in the open, but isn't useful under many real world conditions

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

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.

Put on some music is the cheap and easy option. Combine with a ultrasonic jammer for a robust solution.

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