Would this simple anti piracy idea for cinemas actually work?

May 11, 2012 4:30 AM

1 – I think most camcorders/smartphones have sensors that pick up infrared light and that light then becomes visible to us when displayed on a regular screen. 2 – So could cinemas simply project a message or irritating swirling patterns on the screen with an infra red laser, ruining “cam” copies but not inconveniencing moviegoers?
posted by guy72277 to Technology (20 answers total)

The sensors are usually sensitive to near-IR, but don't pretty much all consumer cameras already employ filters to cut those wavelengths before the light hits the sensor?
posted by solotoro at 4:44 AM on May 11, 2012

I dunno, I used a cell phone camera and digital camera to verify that IR LEDs were illuminated in a few class projects in college and it worked like a charm.

Interesting idea.
posted by olinerd at 4:50 AM on May 11, 2012

Definitely an interesting idea. I just used my camera to diagnose a wonky Wii sensor bar, so seems like something worth investigating.
posted by mikepop at 5:21 AM on May 11, 2012

An iPhone camera can pick up a IR LED directly. It shows up as a dull purple light. The question is whether you can make an IR LED laser pointer, and whether the resulting light is actually visible relative to the very bright projected light. And I'd also not be surprised if a very bright IR source shows up in the visible spectrum, so it wouldn't be invisible to live people.
posted by smackfu at 5:23 AM on May 11, 2012

This seems possible, isn't it how they close-caption films in the theater already? If you look backwards while sitting in the theatre, there is a "bar" that you can see mirror-imaged captions, presumably projecting the captions onto the screen, but they are invisible without special glasses.
posted by InsanePenguin at 5:24 AM on May 11, 2012

Nevermind, I just looked it up. The captions aren't that fancy. Apparently you get some kind of mirror that is attached to your seat and lets you see the captions reflected from the back of the theater. Well, that's less cool.
posted by InsanePenguin at 5:26 AM on May 11, 2012

Is camcorder copying of movies really a problem we need to solve anymore? I like the technical aspect of the idea, just wondering if it is a solution in search of a problem. I thought most pirated current features were direct copies of the source, not a camcorder copy. I know the MPAA thinks it is a problem, but they are idiots.
posted by COD at 5:30 AM on May 11, 2012 [2 favorites]

Unfortunately this would be very easy to defeat - a simple IR filter is cheap and easy to apply and as suggested above most cameras already have one in place...
posted by NoDef at 5:41 AM on May 11, 2012 [2 favorites]

Most films use *visible* light in a choice frames of the movie to watermark where the movie is being played.

(I'm not sure what problem your suggestion is trying to solve.)
posted by devnull at 5:46 AM on May 11, 2012

Copying is more sophisticated now, a common source is a cam shot taken by the projectionist, with audio directly from the sound board (not miced). But he still needs a camera. But anyone serious can probably make or buy and IR filter.
posted by RustyBrooks at 5:48 AM on May 11, 2012

Most films use *visible* light in a choice frames of the movie to watermark where the movie is being played.

OP isn't suggesting a watermark, he's suggesting something that would make the cam capture unwatchable because it would be super annoying.
posted by RustyBrooks at 5:49 AM on May 11, 2012

IR lasers in a room full of eyes seems like a dangerous idea as by definition they will be invisible and do not elicit the reflex to look away or wink if they were to accidentally hit a person who walks in front of the screen.

Also, IR filters are way cheaper than this system, so they would only be inconveniencing themselves. And people who watch CAMs have low standards, they may not be annoyed.
posted by Akeem at 6:37 AM on May 11, 2012

If it's a specific wavelength of light, then it's a simple matter of putting a filter on your lens to get rid of it. And, yes, camera sensors are sensitive to IR and thus already have filters built into them - you can convert a digital camera to a digital IR camera by removing this filter (usually a thin pane of glass over the sensor array).
posted by Jimbob at 6:37 AM on May 11, 2012

There are in fact license plate frames exploiting the fact that cameras are sensitive to near-infrared light to obscure your plate number from speed cameras. They contain infrared LEDs that are invisible to the human eye but which overwhelm the sensor of the speed camera and prevent your license plate from being exposed properly.

This would work quite easily in a movie theater and would not even need to be particularly sophisticated; simply place a strong source of IR light behind the movie screen (they are not opaque) or in front of it washing over it.
posted by kindall at 7:03 AM on May 11, 2012 [2 favorites]

By the way, it is very difficult to filter out near-IR light without filtering out some visible light, which is why most cameras are sensitive to near-IR light to begin with. They all have IR filters in them, it's just that they can't filter too close to the visible range.
posted by kindall at 7:04 AM on May 11, 2012 [2 favorites]

The movie companies have proposed exactly this idea several times. But of course it wouldn't work, since a lot of cameras do have IR filters, and they're really cheap if you don't.

Watermarking technology is really, really good at this point. I imagine that very soon, movie companies will be able to track down the location, time, and date of a recording based on invisible, non-removable information in the movie itself (or maybe the audio track).
posted by miyabo at 7:55 AM on May 11, 2012

There are in fact license plate frames exploiting the fact that cameras are sensitive to near-infrared light to obscure your plate number from speed cameras. They contain infrared LEDs that are invisible to the human eye but which overwhelm the sensor of the speed camera and prevent your license plate from being exposed properly.

There are hats based on the same idea, as well. On the other end of the spectrum (so to speak) removing the IR filter present on most cameras is a technique used to make them suitable for astrophotography.
posted by TedW at 8:07 AM on May 11, 2012 [2 favorites]

And people who watch CAMs have low standards, they may not be annoyed.

So if you could get at a good point in the near-IR spectrum to get around the filtering, just project text that contains spoilers to the movie.
posted by mikepop at 8:52 AM on May 11, 2012 [1 favorite]

Watermarking technology is really, really good at this point. I imagine that very soon, movie companies will be able to track down the location, time, and date of a recording based on invisible, non-removable information in the movie itself (or maybe the audio track).

This is already being done via audio fingerprinting. Busts have been made if the cam person keeps using the same theater.
posted by bitdamaged at 11:01 AM on May 11, 2012

Besides, you're not the first to think if it (apologies for the Gawker link).
posted by Pinback at 4:47 PM on May 11, 2012