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View Full Version : Can infared led's really defeat security cameras?


dstarfire
02-11-2014, 02:27 PM
In one tv show, a thief activates a bunch of infared leds that are built into his hat. This creates the equivalent of a very bright light (that blocks your view of anything beyond it) that's only visible to the security camera.

So, while security guards see a bright blob where a person's head should be, people walking next to the thief don't notice anything out of the ordinary.

Are most security cameras actually sensitive to infrared in this way? Either way makes sense, depending on how you think about it.

CalMeacham
02-11-2014, 03:08 PM
In one tv show, a thief activates a bunch of infared leds that are built into his hat. This creates the equivalent of a very bright light (that blocks your view of anything beyond it) that's only visible to the security camera.

So, while security guards see a bright blob where a person's head should be, people walking next to the thief don't notice anything out of the ordinary.

Are most security cameras actually sensitive to infrared in this way? Either way makes sense, depending on how you think about it.

It depends Cameras can be made insensitive to near IR by using appropriate filters or coatings. But silicon-based imagers, unless so constructed, will be sensitive out to about 1.2 microns, and there are lots of cheap, easily-available LEDs operating between the edge of the visible (say about 700 nm) and 1200 nm.

Most of them won't be bright enough to blind a camera -- they'll just give a bright light on your hat that people will not, in fact, see. But you could rig up a really bright set of LEDs, or use an IR laser pointed at the camera to "dazzle" it. The pointing is the key -- if the LED output or the laser output is direct elsewhere, it won't blind the camera.

Claverhouse
02-11-2014, 03:25 PM
Most of them won't be bright enough to blind a camera -- they'll just give a bright light on your hat that people will not, in fact, see. But you could rig up a really bright set of LEDs, or use an IR laser pointed at the camera to "dazzle" it. The pointing is the key -- if the LED output or the laser output is direct elsewhere, it won't blind the camera.


A kind of Santa Lucia festival for thieves !

Machine Elf
02-11-2014, 03:27 PM
It depends Cameras can be made insensitive to near IR by using appropriate filters or coatings. But silicon-based imagers, unless so constructed, will be sensitive out to about 1.2 microns, and there are lots of cheap, easily-available LEDs operating between the edge of the visible (say about 700 nm) and 1200 nm.

And I think we're only talking about black-and-white cameras here, right? Color cameras would not notice IR wavelengths.

muldoonthief
02-11-2014, 03:45 PM
Color cameras absolutely pick up IR. Take a TV remote and a digital camera or camcorder or camera phone, point the remote at the camera lens and start pushing buttons on the remote. You'll usually be able to see the IR LED flashing in the camera screen. Good way to figure out if the batteries are dead or the remote is just broken too.

Amateur Barbarian
02-11-2014, 03:50 PM
Is anyone claiming this works with non-nightvision cameras? That invisible IR emissions will blur visible-light imaging?

Sounds like a great tactic for night cams, but not full-light ones.

CalMeacham
02-11-2014, 03:54 PM
Is anyone claiming this works with non-nightvision cameras? That invisible IR emissions will blur visible-light imaging?

Sounds like a great tactic for night cams, but not full-light ones.

If your black and white dayvision camera is sensitive to near IR, it will certainly blind it as well (provided your IR source is really bright, and directed at the camera). If your camera has IR blocking filters or coatings, of course, it won't. But a lot of security cameras won't bother with those niceties. Also a lot of inexpensive scientific cameras. You frequently see that, on such a camera, an incandescent light (especially an indicator lamp) seems much brighter than it should (incandescents put out a LOT of IR light). These days, of course, most indicators are LEDs, which won't do that.

TroutMan
02-11-2014, 03:58 PM
It's definitely real, although I've seen it with glasses, not a hat. That way the blur of light masks your eyes.

See here for a video (http://petapixel.com/2013/06/19/these-privacy-glasses-use-infrared-light-to-hide-your-face-from-cameras/) of some in action.

gazpacho
02-11-2014, 04:01 PM
Is anyone claiming this works with non-nightvision cameras? That invisible IR emissions will blur visible-light imaging?

Sounds like a great tactic for night cams, but not full-light ones.Yes they are claiming that IR leds will srew up non nightvision cameras.

Do what muldoonthief suggests. Point you tv remote at your camera and see if the camera shows the IR led lighting up. I just tried this and the remote is really bright and drowns out much of the image.

Ornery Bob
02-11-2014, 05:36 PM
It's from an episode of Castle, and at one point the guy with the IR hat is in his car, driving away and looks to be something like 20-30 yards away from a security cam that's on a high perch. He's also running around killing someone so he's not aiming the LEDs at the camera.

Try the remote control trick with the camera 60 feet away.

Amateur Barbarian
02-11-2014, 05:44 PM
As pointed out, good IR coating on the lenses or an IR filter would easily nuke this trick. Putting it in the class of the guy who walked into a convenience store, walked up to the security camera, pulled out a can of spray paint, and painted the lens solid black.

The tape caught the whole thing. The whole thing.

(So when Mr. James "IR-LED Hat" Bond pulls his trick on a cam that's had an IR filter added...)

beowulff
02-11-2014, 06:18 PM
Yes they are claiming that IR leds will srew up non nightvision cameras.

Do what muldoonthief suggests. Point you tv remote at your camera and see if the camera shows the IR led lighting up. I just tried this and the remote is really bright and drowns out much of the image.

Not good cameras.
The camera in the iPhone is blind to IR LEDs, as is my Nikon D90.

dstarfire
02-12-2014, 12:40 AM
As pointed out, good IR coating on the lenses or an IR filter would easily nuke this trick. Putting it in the class of the guy who walked into a convenience store, walked up to the security camera, pulled out a can of spray paint, and painted the lens solid black.

The tape caught the whole thing. The whole thing.

(So when Mr. James "IR-LED Hat" Bond pulls his trick on a cam that's had an IR filter added...)

Yeah, but it would work as a very effective distraction for a few minutes, especially if you can give the activated hat to an innocent passerby in some area the cameras can't see (in the shadow of a stage, with a bunch of other people walking past in front of you (relative to the camera), etc.)

muldoonthief
02-12-2014, 08:36 AM
Not good cameras.
The camera in the iPhone is blind to IR LEDs, as is my Nikon D90.

So going through every digital camera I could find, all using the same verizon fios remote

motorola droid x2 - bright white light
canon A1000 consumer camera - bright white light
iphone 5 - no light
ipod touch 5th gen. - no light
Samsung galaxy s4 - dim purplish light.
canon prosumer camcorder - no light
old android tablet - very bright white light

So it is very camera dependent.

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