Interpol Unscrambles Doctored Photo In Manhunt 370
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."
Pictures (Score:5, Informative)
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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 (Score:4, Interesting)
Re:Pictures (Score:5, Informative)
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.
Way easier than that.... (Score:5, Funny)
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Re:Pictures (Score:4, Funny)
"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."
Re:Crucial overlooked ideas (Score:5, Insightful)
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.
Re:Crucial overlooked ideas (Score:5, Funny)
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....
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I won't say that photoshop professionals can't do better, but please note:
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;
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
Re:Pictures (Score:4, Interesting)
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.
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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 talkin
Amazing technology (Score:5, Funny)
Re:Amazing technology (Score:5, Funny)
Interpol not the ones to descramble (Score:5, Informative)
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 (Score:5, Funny)
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(Yeah, yeah, OT *grin*)
The actual AP article (Score:5, Informative)
Super-sekr1t unblurring techniques (Score:5, Insightful)
Re:Super-sekr1t unblurring techniques (Score:5, Interesting)
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 (Score:4, Interesting)
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Re:Super-sekr1t unblurring techniques (Score:5, Interesting)
William
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Re:Super-sekr1t unblurring techniques (Score:4, Insightful)
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. :-)
--JoeRe:Super-sekr1t unblurring techniques (Score:4, Informative)
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.
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The degree of blurring isn't really the issue, unless you start to lose information due to quantization losses. Short of that,
Re:Super-sekr1t unblurring techniques (Score:4, Funny)
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 (Score:4, Funny)
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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
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unforuntately that probablly won't work because there is almost certainly interpolation going on.
so you need to run lots of test images to try and calculate how much influence each pixel in the untwirled image has on each pixel in the twirl
Re:Super-sekr1t unblurring techniques (Score:5, Interesting)
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.
Comment removed (Score:5, Informative)
Re:Super-sekr1t unblurring techniques (Score:5, Funny)
P.S. Wow, this comment is on-topic for once!
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Re:Super-sekr1t unblurring techniques (Score:5, Funny)
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I'm fairly certain they used deconvolution [wikipedia.org].
Rellying on the CSI effect (Score:4, Insightful)
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 [wikipedia.org] ".
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.
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It wasn't Interpol who did the descrambling, it was the German police. However, they did imply they wanted to keep the methods secret:
Blurring different from twirling... (Score:5, Informative)
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... (Score:5, Funny)
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Re:Blurring different from twirling... (Score:5, Insightful)
The link about cheques in the summary tells more (if it's that old article I think it is).
Blurring is better than obscuring (Score:2)
Black bars are so passe. Bluring/pixelating is better. Just don't blur your own face. Take your sheriff's photo and blur it all you like...
Re:Blurring different from twirling... (Score:5, Funny)
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Even better would be to not rape little kids in the first place.
Re:Blurring different from twirling... (Score:4, Insightful)
"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.
Blurring not that different from twirling... (Score:2)
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I doubt it is. I recall an article some time ago that showed you could guess words that had been pixellated by statistically analysing what the result looked like. While the same may not be strictly true of a human face, I would not be surprised if they could work out your general features, hair colour, eye colour, and facial features. Enough to produce an artists impression.
It seems if you really want to hide what you look like
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Hardly Rocket Science (Score:5, Insightful)
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 (Score:5, Insightful)
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 [focusmagic.com]. 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 (Score:4, Interesting)
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.
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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 smar
a better solution (Score:4, Funny)
Yes, or you could just stop molesting children and photographing it.
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The idiots will keep doing it regardless.
Status quo.
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Oh dear. I don't think I need to mention how that could be unintentionally misread.
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The best solution (Score:2, Insightful)
Dan East
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Yes, or you could just stop molesting children and photographing it.
And before you know, you've become part of the "think of the children / if you've done nothing wrong, you've got nothing to hide" crowd.
But of course, if we try to protect our identity, we must molest children.
blurring != obscuring; true, but... (Score:4, Informative)
-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.
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Clearly you need to watch more episodes of CSI ^_^
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How to remove numbers/faces from a picture (Score:2)
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Once the data's gone, it's gone... (Score:4, Interesting)
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.
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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.
If the result after blurring is in some way dependent upon the original image, then:
1) If you have a list of suspects, you could apply the same algorithm to each of them and see which one best matches the picture.
2) If you have a blurred-out video sequence, you have a lot of time data to work with. As the camera pans, or the person moves about, different pixels will get blurred in different ways and this will happen in a way that depends on the data of the original picture. Capture enough of these frames,
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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 t
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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 b
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on the other hand a randomly applied blur tool or a block averaging tool is going to be much much harder.
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Re:Once the data's gone, it's gone... (Score:4, Insightful)
In other news... (Score:5, Funny)
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.
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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").
The perfect setup (Score:2, Informative)
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 (Score:5, Funny)
Dalton? (Score:2, Interesting)
The Doctor? (Score:3, Funny)
Oh wait, this isn't about Doctor Who... never mind.
Looks pretty easy.... (Score:2)
Blurring is different, it removes inromation. In some cases blurring might just not remove enough information. For example (as one of the lonks in the story shows), blurring keeps the sum of black and white constant in an area. If you then have to distinguish between a sign with little black in it and one with a lot, that is still possible with blurrs.
Fine, I will discuss the technique. (Score:2)
It is patently ridiculous to imply there is some secret or sophisticated method to undoing the twirl effect as available in Photoshop. All one needs to do is find the bounds of the distortion (which, admitted, is a painful process of trial and error), then perform the distortion with an opposite value to the original. This particular effect is not intended to destroy any pixels, only relocate them, so restoration is intuitive. You can all try this at home: simply load an image, twirl it, then perform the
Manhunt? (Score:4, Funny)
Interpol's got nothin on CSI (Score:4, Funny)
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!
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They've got a bigger budget than Interpol...
More Headlines Like This, Please (Score:5, Funny)
"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"
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Look at how police are compensated. They get rewarded for closing cases. The focus is on arresting a suspect and getting a conviction. Whether or not it's the right person is not part of their pay package.
Actually it is - it comes bundled with the "getting a conviction" part. If you were to demand any stricter proof than that - well, you'll need a psychic. Preferrably one that actually works. It is unclear to me how this could be the basis of any sort of sensible compensation system.
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Reload the link or copy it to the browers' location bar.