Interpol Unscrambles Doctored Photo In Manhunt

jackpot777 writes in with an AP story out of Paris reporting that Interpol has distributed photos of a man suspected of sexually exploiting children. The images were recovered from pictures taken off the Internet in which the man's face had been blurred using something like Photoshop's Filter > Distort > Twirl tool. German police were able to recover recognizable images of the man, whose identity and nationality are not known. Interpol would not discuss the techniques used to recover the images. jackpot777 writes: "It does show one interesting facet of internet privacy that has also been noted with topics ranging from reading blurred check numbers in images to Google's plan to blur out license plate and face data for Street View. And that is: blurring is not the same as completely obscuring. As computers become more adept at extrapolating data of different types, your identity isn't safe unless you completely cover all those identifying features."

Comments

Pictures

[avij]

The pictures can be seen on Interpol's site.

Re:Pictures

[petermgreen]

almost certainly

the way I would approach this is to get hold of all major photo editing packages and then do a twirl in a known location on test images. working from those twirled test images it shouldn't be too hard to work out what is being moved to where. If the packages are scriptable this is a lot easier. If not then its a lot of grunt work.

once you can reverse a twirl in a known location it then just becomes a matter of moving your twirl reversal tool arround until you get a sane looking image.

Re:Pictures

[fractoid]

Well, I'd guess the twirl is a convolution filter followed by a twist. If you can separate it out then you can reverse the twist, and then deconvolve the resulting blurred image, you get the original image. I'd guess. But it's been a while since I did computer vision, and it's probably more complex. :P

Re:Pictures

[allcar]

When I read the headline, I was intrigued. It makes the whole process sound like something from 24. The sort of thing that normally gets me shouting "That's bloody impossible!" at the TV and annoying my wife. However when you look at the actual photo, you realise that the guy, as well as being evil, is a complete fuckwit. At first glance, you know that this is a reversible transformation. This guy should be given a Darwin Award for utter stupidity.

Re:Pictures

[mikael]

A convolution filter would allow you to sharpen or blur the image, or maybe even pick out high frequency detail.

The spiral distort effect is simply a mathematical function to map one point in a rectangular mesh to another. You basically convert integer pixel coordinates into a floating-point coordinate system with the origin at the centre, apply a rotation based on the distance from the origin, convert back into integer pixel coordinates and transfer the pixel data.

Consequently, since every pixel is remapped to a new position, the transformation can be reversed.

Re:Pictures

[ehrichweiss]

At least in this case, it's dealing with filters applied by software, so the algorithm can be examined, and it's perhaps reversible, whilst in 24 they often apply it to things like poor quality or low resolution cameras, and magically enhance the details.

I've got a friend that was charged for burglary one time and the company that charged him submitted their surveillance video footage to some supposed forensics team so they could see if they could derive his face from the blurry video. What was brought to light was that the idiots also submitted my friend's work ID, and an old one that didn't really look like him any more, with the video. The team then returned a video that showed how they "matched" my friend to the person seen in the video...they morphed several stills grabbed from the video with....you guessed it...my friend's ID and THEN they showed their derived picture right next to the old ID. I took one look at it and told him they had absolutely zero case against him if that's all the evidence they had. I didn't even have to show up as an expert witness since the judge was wise enough to realize what was going on.

Re:Pictures

[badasscat]

At least in this case, it's dealing with filters applied by software, so the algorithm can be examined, and it's perhaps reversible, whilst in 24 they often apply it to things like poor quality or low resolution cameras, and magically enhance the details.

And the article summary here definitely confuses the two, talking at the end about blurring license plates as if it's the same thing as what this guy did.

I have yet to see any evidence that a properly blurred image can ever be recovered. People keep talking about it, but they're talking about getting blood from a stone. Blurring is by definition a loss of detail. You cannot restore lost detail; you can only try to approximate what that detail was. (The article posted here a while back, and linked through the summary above, is talking specifically about extracting numbers from a mosaic'd image, not a blurred one. In any case the author says specifically that it only works when you're trying to choose from one possibility out of ten choices, ie. a number.)

Let's say you have an image that you blur to the point where it's nothing but a sheet of grey color. There is nothing in the world that could ever revert that image back.

The only question is how far you have to blur something to get to that point. Some people may not go far enough, and their images can be extracted. But there is a point of no return.

What this guy did, though, was use a filter that preserves nearly all detail but simply distorts it. And any distortion can be un-distorted. That's a different thing entirely than extracting detail where there is none to extract.

Some types of image manipulation destroy data; others don't. "Blur" destroys data. "Twirl" just moves it around. That's the difference.

Re:Pictures

[slimak]

This is pretty standard stuff in almost any junior/senior level signal or image processing course. Whether the operation can be undone depends heavily on the type of blurring. For example, if the blurring operation is linear then it can be represented by a matrix operation. This means we can write the blurred image (y) in terms of the blurring kernel matrix (H) and the original image (x) as: y=Hx (assume x and y are column vectors of all image samples). This operation can be inverted perfectly as long as H is a non-singular matrix as: x_hat = inv(H)*y = inv(H)*H*x = x.

When H is singular or non-rectangular the typical approach would be to make x_hat = inv(H^T*H)*H^T*y, which is the least-squares approximation of x from the blurred observation y (^T denotes matrix transpose).

When the operation is non-linear it generally get MUCH harder. Here, the most common approach would be to use some statistically optimal method or incorporate a priori image information.

Re:Pictures

[Beardo the Bearded]

Thoughts on why they want to keep the technique secret:

"Woah, we caught a break, sir. That pedophile just used a twirl filter."

"No kidding? Did you get his face out of th..."

"Already done. Hopefully more of those assholes will use that twirl filter."

"Yeah, good point. Keep it quiet. I'll make up some story about secret techniques and taking six months."

"Oh, sir, one more thing. We really should get a legitimate copy of Photoshop."

Amazing technology

[alx5000]

Amazing, indeed

Re:Amazing technology

[DaveCar]

It doesn't work that well. They guy on the left looks all wonky and strange.

Interpol not the ones to descramble

[packeteer]

From the interpol web page it says:

These pictures have been produced by specialists from Germany's federal police force, the Bundeskriminalamt, working from originals found on the Internet, which had been digitally altered to disguise the man's face.

Re:Interpol not the ones to descramble

[Hognoxious]

Ummm, about your sig. In this context? You're not him, are you?

Re:Interpol not the ones to descramble

[ubrgeek]

Chiefbutz, you are a madman.When you stole that cow, and your friends tried to make it with the cow. I want to party with you, cowboy.

(Yeah, yeah, OT *grin*)

The actual AP article

[avij]

.. can be read here.

Super-sekr1t unblurring techniques

[acb]

Surely Interpol's top-secret image-unblurring technology is just a matter of applying the Twirl effect in the opposite direction at the same location, and perhaps applying some image-enhancement plug-ins to the resulting area? I doubt it's anything one couldn't do with off-the-shelf software.

Re:Super-sekr1t unblurring techniques

[Anonymous Coward]

The AP article did mention that AP were able to produce an almost recognizable image using commercially available photo editing software but not a good as the one Interpol had produced.

Wild ass guess ahead...

Interpol geeks probably ran some tests to determine approximately how much twirl was applied to the original image and then created a 24bit image slightly larger than the twirled area assigning a unique 24 bit value to each pixel and then applied the same amount of twirl.

They could then look at the twirled test image and come up with a mapping of twirled pixels to untwirled pixels. This information could be used to "untwirl" the original image by grabbing the pixels at the twirled coordinates and moving them back to where the mapping says they probably originated.

Of course there would be some pixels lost and extra pixels created during the original twirling but chances are the original image could be approximated fairly well by interpolating between the recovered pixels. You'd not get a picture perfect result but something somewhat blurry as can be seen in the recovered pixels.

Of course they might have done something more mathematical but if I was going to try this myself I'd probably just give the method I described above a shot first and see if I came up with something looking like a face.

Re:Super-sekr1t unblurring techniques

[somersault]

Yep, I don't see what other way there is to do it rather than just reverse the process :P It's funny seeing some people say it's 'amazing', and also it's a dumbass way to try to disguise something. I don't think the summary is accurate in thinking that blurring can be undone to the same extent as to get a license plate back or whatever.. it would be possible to get a bit of detail back if there wasn't too much blurring being done, but say you applied a very heavy gaussian blur to a section of a picture, everything would basically get mashed into one colour..

Re:Super-sekr1t unblurring techniques

[drspliff]

I've just tried this using Photoshop's twirl plugin, and with a little tinkering arout I could get a fairly good descrambled picture in only 10 minutes.

With more time and higher quality images, I'm sure it wouldn't be any trouble at all, it just needed the initial insight to use the "swirl in opposite direction" idea.

Re:Super-sekr1t unblurring techniques

[Lord Crc]

Surely Interpol's top-secret image-unblurring technology is just a matter of applying the Twirl effect in the opposite direction at the same location

I'm fairly certain they used deconvolution.

Re:Super-sekr1t unblurring techniques

[Anonymous Coward]

Amazing! I tried it too. Did the twirl thing as far as it would go then used "undo" to reverse it and you really could not spot any difference AT ALL!

Re:Super-sekr1t unblurring techniques

[Anonymous Coward]

In an unbounded picture with infinite intensity resolution, the point spread function of a good old fashioned blur does not destroy information. Then you can recover the image through a process called deconvolution. In the real world, information is lost at the image boundaries and due to requantization, plus you don't know the PSF. If the blur does not cover the whole image and there's only a small number of likely PSFs (as would be the case if the blur was produced in one of the popular image editing programs), two of these deconvolution limitations are already gone and you're only dealing with quantization noise, which isn't so bad if you're only looking for high contrast information like number plate letters. It gets easier if you have multiple pictures or even video.

Re:Super-sekr1t unblurring techniques

[WillAdams]

That's why when I need to obscure a face (when working on images for a medical journal) I use the mosaic filter after running a heavy gausian blur --- leaves something recognizable as a face, but w/ too little information to reconstruct even a postage stamp (~10 x 16 pixels).

William

Re:Super-sekr1t unblurring techniques

[Stradivarius]

Actually you can do the same sort of operation to unblur a license plate. In fact that was a lab exercise in one of my college signal processing courses :-) The main concern I'd see with the license plate problem would be ensuring your camera sampled the data fast enough to meet the Nyquist criterion. But if you did, you'd have all the information content in the image you'd need.

The degree of blurring isn't really the issue, unless you start to lose information due to quantization losses. Short of that, it's a matter of A) being able to guess or approximate the original blur operation, and B) the fact that "blur" operations are generally reversible (they're simple linear shift-invariant filters, and you're not losing information in that process). So you just apply the inverse filter to the image (or subset of the image). If you don't know the exact original blur, you can attack the problem by brute force and just try inverses of many different blurs until one looks fairly good.

If you really want to obscure something in a non-reversible way, remove the data from the image (overwrite it with a black box or something). That's far more reliable than applying even the heaviest of blurring filters.

Re:Super-sekr1t unblurring techniques

[richlv]

If you really want to obscure something in a non-reversible way, remove the data from the image (overwrite it with a black box or something).

if you are from a government, remove the data from an image with the alpha channel and don't uncheck "save color values from transparent pixels" (in gimp).

Re:Super-sekr1t unblurring techniques

[FuzzyDaddy]

(they're simple linear shift-invariant filters, and you're not losing information in that process)

Which points to the difference between the computational and physical worlds. If I blur an image by, say, projecting it through a lens on a piece of film, I reduce the amplitude of the high spatial frequency components. As you say, this isn't a lossy process. The difference in the physical world, there's noise added at every step, and the physical blurring reduces the signal to noise in the higher spatial frequency components, causing some true loss of information.

Doing a blur in photoshop reduces the amplitude of the high spatial frequency components as well, but there is no added noise - so the process is reversible.

Re:Super-sekr1t unblurring techniques

[RatCommander]

I'm fairly certain they used deconvolution.
No, I'm fairly sure they didn't. Deconvolution is only applicable to linear systems - this "twirl" filter is non-linear. A better bet would be something like the reverse mapping approach mentioned elsewhere in this thread.

Re:Super-sekr1t unblurring techniques

[jamesshuang]

Why not just use the simplest one - a black box? Information can't be extrapolated from something that doesn't exist. Also, I doubt you'd have problems with recognition - if anyone sees a body, neck, and a black box, I doubt they'll think you have decapitated people running around...

Re:Super-sekr1t unblurring techniques

[Mr Z]

Another fun technique is to just paste something plausible there—like another face, or pieces of other faces—before blurring. I often do the same thing when blurring out numbers. You might be able to get away with a plasma fractal with appropriate skin tones.

I figure it gives the hacks something to get excited about until they realize it really is gibberish. :-)

--Joe

Re:Super-sekr1t unblurring techniques

[AmiMoJo]

Your method is not entirely foolproof. The problem is that someone can repeat the steps you took and compare the results. They could photograph a person in the same pose, apply the same or very similar filters and if the results match, there is a good chance the source images were also quite similar.

A similar technique was used to guess blurred out numbers on cheques, passports, car number plates etc. Simply run through all possible combinations of letters and numbers, applying a mosaic each time until the mosaics match.

Re:Super-sekr1t unblurring techniques

[Random832]

It's easier to just draw black boxes over it then save as XCF (since if you try to save in another format it warns you about "flattening" the image, whatever that means)

Re:Super-sekr1t unblurring techniques

[mattOzan]

Show us pictures of your wife!

P.S. Wow, this comment is on-topic for once!

Re:Super-sekr1t unblurring techniques

[butterwise]

they did imply they wanted to keep the methods secret

Why bother? I sure won't be using that method to mask my identity ever again...

Blurring different from twirling...

[Max Romantschuk]

A twirl is essentially shifting pixels around an image, and is designed to keep as much information as possible.

A blur on the other hand, especially a gaussian blur, will mix pixels together in such a way that any recovered image will be one of many possible outcomes.

Then again, removing information, by pixellating for example, would be best.

Re:Blurring different from twirling...

[ultrasound]

Surely the most effective filter would be a GIMP mask?

Re:Blurring different from twirling...

[KlaymenDK]

Pixellation is only effective if done really, really coarsely ... so you might as well just opt for the classic black bar to begin with.

The link about cheques in the summary tells more (if it's that old article I think it is).

Re:Blurring different from twirling...

[baldass_newbie]

Then again, removing information, by pixellating for example, would be best.

Even better would be to not rape little kids in the first place.

Re:Blurring different from twirling...

[hcdejong]

Or do it in hardware instead: Black bar glasses.

Re:Blurring different from twirling...

[apparently]

Who are the alleged victims?

"Alleged" implies that a picture of an adult molesting a child, constitutes only an "alleged" crime.
"There were no rape report from anyone" implies that a picture of the act being conducted isn't enough. That the 4 year old Cambodian sex slave needs to file a proper report.

In a discussion regarding the photographically documented molestation of small children, you want to expand the discussion to include statutory rape allegations between teenagers. How about we also talk about taxidermy and monster trucks? Because if you think there's any similarity between the teenage sex issue and child molestation, then any "discussion" with you might as well go down those tangents as well.

Re:Blurring different from twirling...

[R2.0]

Sorry, you are on the wrong end of this argument on a couple of accounts:

1) Ad hominem attack, invoking the OP's "set aside their emotions and have a rational discussion on this topic", as well as the first response (possibly not you, but definitely sympathetic) invoking a religious bias that was not in evidence - no invocation to God was made, and "evil's advocate" has been a thoroughly secular phrase for hundreds of years.

2) You are attempting to invoke the spectre of censorship of discussion when teh discussion has no bearing on the topic. "the fascination discussion around the actual origins of consent and rape laws" really has no bearing on the topic at hand. There are pictures of an obviously adult make (pushing middle age) engaging in sexual acts with individuals who are obviously pre-pubescent. Such young individuals CANNOT, under any modern (or even archaic, to my knowledge) legal theory, give consent to a sexual act. Those photos are prima facie evidence that a rape has occurred, unless we want to wander off into NAMBLA land. Now, if they find this guy, and he can show that the pictures were faked, he had a gun to his head, they were actually 40 year old midgets, then he could argue his case. But to a reasonable person, those pictures show a rape occurring.

3) You are picking the wrong example to argue your case. If indeed the subject had been having sex with pubescent or older youths, one might argue that consent was given, etc. There are indeed gray area in law and morality. This is not one of them. You are proposing a classic slippery slope arguement: because some young people might be able to consent to sexual activity, ALL young people might be able to consent http://www.don-lindsay-archive.org/skeptic/arguments.html#slippery I could just as easily take the convers: because the very young cannot give consent, than no one under the age of 21 can give consent. You reject that argument, butit is just as specious as the one you are making.

In short, you've picked a loser. You intend your arguments to make you appear reasoned and rational; instead you come off as hair splitting and equivocating.

Come back with a better subject next time. Good day to you.

Hardly Rocket Science

[clickclickdrone]

>Interpol would not discuss the techniques
I showed this to my PS using friend and he shurgged, said 'Just do a radial blur in the opposite direction' and 30 seconds later had a picture about 80-90% as good as the one they're waving about as being the result of some super secret methodology.
It does strike me as a bit stupid explaining it all - now crims will just use better techniques for blurring themselves out. The media, law enforcement agencies are doing this more and more and it's insane - "we just had an idea for a terrorist attack that might happen and here it is in full", "This is foresnic evidence that allowed us to catch the crim" and so on.

Re:Hardly Rocket Science

[suv4x4]

I showed this to my PS using friend and he shurgged, said 'Just do a radial blur in the opposite direction' and 30 seconds later had a picture about 80-90% as good as the one they're waving about as being the result of some super secret methodology.
It does strike me as a bit stupid explaining it all - now crims will just use better techniques for blurring themselves out. The media, law enforcement agencies are doing this more and more and it's insane - "we just had an idea for a terrorist attack that might happen and here it is in full", "This is foresnic evidence that allowed us to catch the crim" and so on.

Yup, they spun it (pun intended) into cheap PR. The problem is, it's not that they are super smart, it's that the criminal was super stupid.

And it'll make anyone with basic image processing skills question their overall expertise if they'd brag about untwirl.

That said, the average folk will definitely be impressed. I knew a guy who inverted his photo in attempt to protect his identity (no, he didn't molest children). Imagine his shock when I took the inverted photo, inverted it again arriving at the original.

To him I'm probably some sorta super genius who used sophisticated data restoration hack. To a guy with basic knowledge, it's nothing worth noting.

To see how blur can restore detail not visible to the naked eye, check out Focus Magic. Not as easy as untwirl, but gives you an idea. This is because the blur distribution (usually gaussian if digital, or linear with cameras) gives away the possible origin position of the pixels.

If you pixelize however, with big enough square, you lose real resolution and that's much harder to restore anything interesting out of (it's not like in movies, with the unlimited extrapolation techniques, as we all know).

Other gotchas: covering with black rectangle but leaving it only 1-2% transparent. Looks solid, but data can be recovered.

And a very common other method: people keep leaving their name and camera model in the meta info of the image. Easy to check out via right-click>Properties in Windows.

PS: it was "twirl", not "radial blur" btw.

Re:Hardly Rocket Science

[suv4x4]

I also wonder if you could recover an image of someone's face from pixelated video. If the camera or the person is moving but only slightly then you may be able to determine the x,y movement of the whole image from the non-pixelated parts of the image. From this you can then consider each of the large pixelated pixels as a sample point on the person's face, and as they move you aquire additional sample points. Over enough time, say a 5 minute interview, you might be able to reconstruct a recognisable face.

Ah, good point indeed. If it's a video, yes, you can restore extra detail.

There are lots of cameras out there which use a simple version of this trick to shoot higher res photos than their matrix is (by shooting several photos with sliightly offset matrix and assembling those).

And there's already software in wide use which can take existing video footage of, say, recording a page of a book for a while with low resolution, and using the minor motion/shifts in the frame to automatically arrive at a much higher (and accurate!) resolution image. It's amazing the amount of detail it can restore.

Since pixelization is in fact reducing the resolution, the same applies there.

I guess the only sure method is not to leave anything that can be analyzed. Don't wanna be recognized.. ? Don't allow to be recorded/shot.

a better solution

[User 956]

As computers become more adept at extrapolating data of different types, your identity isn't safe unless you completely cover all those identifying features.

Yes, or you could just stop molesting children and photographing it.

Re:a better solution

[IndustrialComplex]

Sadly they will CONTINUE molesting children and STOP photographing it. It pushes against my freedom of information beliefs...

Oh dear. I don't think I need to mention how that could be unintentionally misread.

blurring != obscuring; true, but...

[Animaether]

true, blurring isn't the same as obscuring. That said, a twirl/swirl filter isn't a blur filter either. A twirl/swirl filter relocates pixels from position A to position B. The original pixels are still largely there, you just have to move them back from B to A. That's what Interpol did here - kudos to them for figuring that out. But a blur filter doesn't just relocate pixels - it blends a bunch together. Now don't get me wrong - there's certainly deconvolution methods to reduce blur - especially motion blur - ( one example software: http://www.focusmagic.com/ ) but you're not going to be able to just take any heavily non-motion blurred image and get a supersharp result back. Other techniques, such as pixelization, are even worse to restore - you may as well not try.

-That- having been said.. yes, obscuring does tend to be better.. as long as it's a proper obscuring and not some half-hearted attempt by a news station where an interviewer / whatever has said to want to be inrecognizable, and then you just get a dark silhouette of the person where you can 1. still make out the silhouette, 2. their voice goes unaltered, 3. bump up the brightness enough and you can even make out a face or, in the case of yea olde license plate, a black bar that is supposed to 'track' the license plate properly, but the person applying the bar is a lazy-ass tracker and it 'swims' over the plate, revealing tiny bits of the bottom/top on certain frames - not too much guesswork involved to figure out the proper license plate, as even with multiple possibilities, only one is likely to match the type/color of the car when looked up on the interwebs.

Now then... Let the "what if somebody photoshopped somebody else's head on there first, then applied the filter, now some poor innocent sap is framed!" replies begin.

Re:blurring != obscuring; true, but...

[Aokubidaikon]

you're not going to be able to just take any heavily non-motion blurred image and get a supersharp result back.

Clearly you need to watch more episodes of CSI ^_^

Re:blurring != obscuring; true, but...

[ockegheim]

Yes, with focus blur, you have the same number of pixels as you would otherwise have, just mixed in a way that isn't immediately obvious. Though I suppose if the Hubble Space Telescope required corrective lenses, it mustn't be all that easy.

Re:How to remove numbers/faces from a picture

[chuckymonkey]

Honestly though, how many people think like that? Most people are not going to be aware of an organization's ability to de-obfuscate an image and will not take the appropriate steps to hide their identity. The only thing I worry about in this post is the lack of peer review in source code, I believe that if the government is going to use software that may have a negative impact on a person's life (not saying this guy is innocent, just in general) then the source needs to be freely available for peer review so that the margin for error can be out in the open and the quality of the code verified.

Once the data's gone, it's gone...

[Gordonjcp]

As computers become more adept at extrapolating data of different types, your identity isn't safe unless you completely cover all those identifying features.

Uhm, no. As other posters have pointed out, all they did was reverse the distortion applied to the image - which in this case didn't really lose much information, just nudge it about. If you blur out someone's face, the detail can never be recovered. No, not even by the NSA. The information is lost. You *can* sharpen up edges and improve contrast, but if the information just plain isn't there any more there's not a lot you can do.

Think about it this way. A digital image is just a string of numbers. If I take a string of numbers and apply a "filter" to it then I get (0.4, 3.0, 6.2, 3.4, 5.4, 5.8, 2.6). From that, can you work out what the original values were? Possibly, because my filter is very simple. However, you don't know how much precision has been lost, or what the initial values were, so it would be nigh-on impossible to work out the original values.

Incidentally if anyone does work out the original sequence, I'd love to hear about it.

Re:Once the data's gone, it's gone...

[cnettel]

Also, for check numbers, as well as facial features, we expect a quite specific structure. This means that the set of possible original images is not uniform, so it's quite possible to detect a remarkable level of detail (like the specific check number, if the font is well-defined), even when a lot of information has been lost.

Re:Once the data's gone, it's gone...

[IndustrialComplex]

Not when you phrase it like that. Of course you can't get the 'exact' data back, but you can get an approximation. And think about what a digital picture is in the first place. It is an approximation of an image in a pixelated form.

Exact doesn't matter in terms of identifying a person via a photograph. While 'how' exact is left to a jury, you cannot claim that ANY picture is an exact reproduction of the original image. There is ALWAYS loss.

The photograph or in this case, unblurred image only needs to be close enough. And 'enough' is defined by the person who will use the image. The user could be a jury, an investigator, a judge... each would have their own definition of how important the unblurred image is.

Re:Once the data's gone, it's gone...

[26199]

It's interesting to note that given enough precision a blur is fully reversable.

In the frequency domain, a guassian blur reduces the amplitude of high frequencies; it doesn't drop them to zero. Simply multiply up again to get the original image.

Now, in practice this doesn't work particularly well because the high frequencies end up with such low amplitude that quantization destroys them.

The reason there is still a potential problem is that the 0-255 precision used on computers holds more information than the human eye can fully perceive. So it may be possible to unblur things when, to a person, the information is gone.

In other news...

[djupedal]

"As computers become more adept at extrapolating data of different types, your identity isn't safe unless you completely cover all those identifying features.""

New laws were passed today, making it a felony to obscure, obfuscate, scramble, cover or otherwise purposely mask your identity by modifying a digital image for the purpose of avoiding identification by law enforcement agencies.

Re:In other news...

[Tim C]

Actually, I could see someone trying to make a case that that's either obstructing the police or attempting to pervert the course of justice, assuming that you were caught for whatever it was that you're accused of.

Don't forget though that a number of things that are legal (eg carrying a crowbar while out and about) become illegal if you are engaged in a related crime (carrying that crowbar while breaking into a house becomes "going equipped").

Re:In other news...

[Punko]

If the image is altered prior to the image being declared evidence, then it is not illegal. wiping your fingerprints from a glass is not illegal, unless the authorities have already tagged the glass as evidence.

The perfect setup

[Anonymous Coward]

How soon before someone Photoshops in the face of someone they don't like into KP, obscures it, then releases it knowing the cops will unobscure it and arrest him?

When he claims "it wasn't me" will he be able to prove it? Sure, the cops are supposed to have the burden of proof but when it comes to bogeyman charges like terrorism and KP juries usually go with the prosecution regardless.

Hmm

[SamP2]

I wonder when I'll be able to buy the software that automatically unscrambles all the pixelated regions on my rather specific-content Japanese DVDs.

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The best solution

[Dan East]

How about if they stop molesting children. Period. I doubt it makes much difference to a 4 year old whether or not photography is involved while they are being sexually assaulted.

Dan East

Re:You realize why they are saying all this?

[suv4x4]

The average person out there really does not understand computers. As such, the criminals look smart, and now the police look even smarter. It is hoped that by making the cops appear to be intelligent that other criminals will stop as well as perhaps the cops will get more money for this.

Fear of the unknown is a better weapon, than giving forensic analysis tutorials to the entire world.

And what they achieve is they look dumb now, since anyone having a clue knows the transform is basic. It may push some smarter people doing a crime since they believe if the police is so proud with their untwirl, they must be on a pretty low level overall.

I'm not saying this will make smart people molest children and shoot photos of themselves, but still, your reason is weak..

Dalton?

[The Yuckinator]

Am I the only one who thinks this guy looks a bit like Dalton McGuinty? Given that we heard about his other habits right before the last Ontario election.....

The Doctor?

[FlopEJoe]

See, I'm not a fan of the story arcs, "the Doctor is mistaken for a bad guy." For one, they never seem to go very far. Like that guy harassing Martha's mother in the middle of season three? I thought that was going to go somewhere and...

Oh wait, this isn't about Doctor Who... never mind.

Re:How to remove numbers/faces from a picture

[Asic Eng]

It's the judge's job to handle this, if the guy is found and brought to court. If the picture is a major piece of evidence he may order the source code (or the sequence of actions they executed in photoshop) to be examined. I suspect though that the picture would only be used as a way to track this person. As a starting point to gather more information, not as acutal evidence in court.

Manhunt?

[RandoX]

Am I the only one disappointed to find out that this doesn't have anything to do with the Rockstar game?

Interpol's got nothin on CSI

[Jtheletter]

If this were an episode of CSI They could have simply drag-and-dropped the photo into their "automatically un-distort face in image" program, then zoomed in over the man's shoulder to read the artist's signature of a painting behind him. Then recognizing that these paintings are only sold from one obscure store in New York City, they drag-and-drop the photo into their "compare to every frame of every NYC ATM to this picture" program and found a frame of him standing conveniently in front of his license plate, which they could also zoom in to read the registration sticker text.

Get with the times Interpol. Sheesh, CSI wouldn't even have had to use their "match a partial fingerprint I zoomed in 6000% to get off of a glass of water in a 72dpi jpeg to every known felon in the US in under 10 seconds during witty banter" program to solve this one!

Re:Interpol's got nothin on CSI

[LynnwoodRooster]

Dude, it's freaking Hollywood!

They've got a bigger budget than Interpol...

Rellying on the CSI effect

[DrYak]

Yes, for the average /.er this is absolutely trivial :
the idiot used a filter that just moved the data around in predictable way (in circles), and the police did transpose the data in the opposite direction and got the picture back. The picture was not blurred at all (in the mathematical sense of lowering the resolution).

Interpol bragged about it not because of some obscure technical feat. They bragged about as a PR stunt, in order to take advantage of the " CSI effect ".

Joe 6 pack, has recently started to understand that incredibly big zooms, with some magical "picture enhancement effects" that keeps incredible amount of details - as done by Deckart in Blade Runner, or regularly featured on CSI - can't be actually achieved in real life. Because everyone is criticizing those shows for the lack of realism in their zooming achievement.

But now Interpol pulls this PR stunt, where they show how they managed to recover the identity of the maniac. Now people every where are starting to think "Oh may god ! They actually have the technology ! They can "enhance" pictures and get the faces back !". The goal of Interpol was to instill fear in would-be criminal who would hope to stay anonymous with some photoshop tricks tricks. Maybe this wasn't the only stuff that was openly criticized in CSI but that was secretly doable by the real police. Now cue-in some armchair conspiracy theorists, who could pretend that the whole criticizing of "unrealistic police TV-shows" was a government conspiracy to cover up technology that actually exist (additional points earned if technology is of alien origin), or they could say that government has put a backdoor inside Photoshop that does keep the blurred faces saved in steganography (bonus point for using buzzword).

They are creating a climate of FUD, in the hope to deter would-be criminals.

Comment removed

[account_deleted]

Comment removed based on user account deletion

what i've always found crazy about digital images.

[yodleboy]

what i've always found crazy about digital images... i'm looking at a blank monitor screen (don't get smart, i have 2 monitors). on that screen, every possible image no matter how private, or bizzare is available by just activating the correct pixels. seriously, every scene from history. every fantasy. in photo realistic detail. what if there was a program that would plow through every possible combination. what images might pop up? why waste bluegene on chess? creepy.

Multiple Images helped Interpol

[fast turtle]

Everyone who's talking about blur/twirl/pixelation has forgoten the important thing. Interpol had multiple images. Think of this as having several frames from a film. This gave them enough information to not only un blur/twirl but to compensate for pixelization. So there was a bit more then that used to get the recovered images

Re:Crucial overlooked ideas

[djh101010]

They could then look at the twirled test image and come up with a mapping of twirled pixels to untwirled pixels. This information could be used to "untwirl" the original image by grabbing the pixels at the twirled coordinates and moving them back to where the mapping says they probably originated.

It probably helps a LOT that in several of the images, there's a strong line visible in the background. Measure the twirl of that, you've got your benchmark right there. Center of the twirl is probably easy enough to locate too. So there's your twist, and where to apply it.

It's a good thing so many criminals are dumb. It's the smart ones that you have to worry more about.

More Headlines Like This, Please

[Minwee]

"Interpol Unscrambles Doctored Photo In Manhunt"

"Interpol Unlocks Les Paul in Guitar Hero II"

"Interpol Tracks Down Level -1 in Super Mario Bros."

"Interpol Acquires 'Marathon Man' Achievement in Halo III"

"Interpol Microwaves Weird Ed's Hamster in Maniac Mansion"

Re:Crucial overlooked ideas

[sunderland56]

It's a good thing so many criminals are dumb.

Who says he's dumb? If he carefully photoshopped someone else's face onto his, and then applied the easy-to-remove swirl, he now has the entire planet searching for the wrong guy....

Way easier than that....

[ProfessionalCookie]

Edit >> Undo

Re:Crucial overlooked ideas

[mce]

I won't say that photoshop professionals can't do better, but please note:

1. I did not say I'm a photoshop novice, I only said that I tried that particular thing once and thet the result was no perfect;

2. Mirroring faces does not work, as human faces are not symmetrical.

   Try it: take a picture of a face, and make one in which the left half is a mirror image of the right half and one in which the right half is a mirror image of the left half. Not only will you find that both versions differ, but it is even the case that one of them consistently looks more friendly/pleasant than the other one. This implies that if you just mirror a complete face, the manipulation is easily detected, since the wrong half will now yield the nicer picture.

   Besides, the whole mirroring thing can not even be considered if the picture shows the face at angle.