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Detecting Faked Photographs Gets Easier 258
nusratt writes "Some years ago, an issue of 'Whole Earth' had a convincing cover-photo of a flying saucer cruising low over downtown San Francisco in broad daylight. The accompanying feature article proclaimed that photographs can no longer be trusted as evidence of anything, because of the ease of doctoring images digitally and undetectably. Now, Dartmouth Professor Hany Farid and graduate student Alin Popescu 'have developed a mathematical technique to tell the difference between a "real" image and one that's been fiddled with.' Farid says, 'as more authentication tools are developed it will become increasingly more difficult to create convincing digital forgeries'." There's also an NYT story.
Seamless Math Next? (Score:5, Interesting)
1. Forgers get smart and use older cameras to take a picture of a digital forgery to pass as an original, using blurring techniques offered by physical means and lens... etc (easy)
2. Forgers quit being forgers (unlikely)
3. Alteration technologists create armor against image forgery detection algorithms (possible)
For me, I think any time spent trying to beat the detection of forgeries would be a good thing in terms of art and creativity -- not to mention the possibility of better digital growth algorithms to join layers mathematically seamlessly (which could be used in games and simulation engines for better realism). However, law enforcement agencies might try to combat the circumvention of forgery detection by charging people with crimes for only trying to make their images more realistic and improve technology. It's a messy issue, that will sort itself out over time.
In Doom 3 Bloopers, a mod I've started on, I am looking at ways of integrating realworld imagery into the mod, and this detection stuff could actually help me to better integrate my own art and images if I can find a way around it. Let's face it, if the math says it's an original, the human eye will be fooled, which is the goal of most video game design. If anyone wants to help along those lines, they should contact me [zenbuzz.org]!
Re:Seamless Math Next? (Score:4, Insightful)
You, sir, have balls!
Re:Seamless Math Next? (Score:5, Interesting)
Why wouldn't someone simply build a filter into a program that changed bits in an image until it passed a check by their algorithm - on failing, it would simply go back and change more appropriate bits?
Seems as though it would be a computationally intensive but a logically easy task.
Re:Seamless Math Next? (Score:5, Insightful)
My first thought on the article was the same. The mathematical tests to determine fake photos will have value only until the fake photo industry builds the tests into their software. For that matter, I suspect that the main use of the Hany Falid method will be to make your fake photos even more realistic.
The most interesting line in the article was:
One could read into these lines that the ability to fake photographs was great until anyone could do it. Now that we know how easy it is to fake photographs, we no longer implicitly trust messages...but we will trust mathematically authenticated fake photographs because math is infallable.
Re:Seamless Math Next? (Score:4, Insightful)
Or you could read into them that when it was rare and difficult to fake photographys, most of the photographs you saw were genuine, so you could place a decent amount of trust in what you were seeing. Now that faking photos is easy and commonplace, you can no longer place much trust in photos. With mathematically verified photos, you can place more (though not complete) trust back in the photo. It isn't foolproof but the level of assurance is significantly higher.
Re:Seamless Math Next? (Score:5, Interesting)
Or you could realize there's inherent error in any statistical method, and that with a little bitof foresight, this error could be expoited to provide false results. The best detector of falsified photography is still a well-trained human eye. The key to knowing whether or not to trust images is to train your eye.
Re:Seamless Math Next? (Score:4, Insightful)
Most of the early photos you come across were staged. Taking a photograph was a big deal. People dressed up in their best outfits and the photographer would construct the scene. Often the photographer colored or otherwise enhanced the image. Photography has always been an art form. As an art form, people choose the message to convey.
Using photographs as evidence has always been problematic. The struggle is for lawyers to keep enough faith in photos to be able to use them in court. Personally, I think having a method to declare a photography mathematically correct immediately creates a problem where people with sufficient resources to fake mathematically correct fake photos will have the ability to manipulate the courts.
There never was that much faith in photographic evidence. I think we are better of having doubts about photographic evidence than we will be if we sanctify any photos as mathematically correct. The methods will have some value in quickly identifying tampered evidence, but will not have value in verifying it.
Re:Seamless Math Next? (Score:4, Insightful)
You're also quite correct that photos are routinely manipulated in the dark room. However, manipulating the color and otherwise enhancing the image is not at all what most people mean by a "fake photograph." There's a fundamental difference in those types of manipulations and putting Sarah Michelle Gellar's head on a porn star's body or putting John Kerry and Jane Fonda on the same podium [snopes.com] together. This type of thing was possible before, but it was much, much more difficult and much less common.
Re:Seamless Math Next? (Score:4, Interesting)
One example photo from the beginning of the last century or before, depicted two figures by a lamppost on a foggy Parisian street. I took it for an unaltered print, but it turned out to be a composite of seven [!] separate images. It was laboriously done in the darkroom. It was incredible. (Unfortunately, I can't find the specific photo on their otherwise excellent site.)
Now, we've all seen great darkroom manipulation like the work of Jerry Uelsman (www.uelsman.net), but this particular picture was a hundred years older than his work. It was absolutely convincing.
I guess my point is, photographs have in fact been "faked" as long as there have been photographs.
Re:Seamless Math Next? (Score:5, Insightful)
Probably. Consider this, though: Fingerprints are common knowledge. We ALL know that if we commit a crime, fingerprints will be lifted to try to catch us. There are well known ways to defeat this, but remarkably, LOTS of people are still leaving fingerprints as clues at a crime.
I hope you can forgive me for reading a little more into your post than you actually said. I don't know for sure if you were going the "this could easily be defeated, thus it is ineffective" route. But I thought this would be as good of time as any to mention this.
Re:Seamless Math Next? (Score:2)
Perhaps some of the forgers(maybe just the ones who used to forge paintings *tongue in cheek humor*) already do pay such attention, after all, attentio
Re:Seamless Math Next? (Score:4, Interesting)
Don't be so sure about that!
I don't know what these researchers are doing, but I can venture a guess. You can think of an image as being composed of a large set of superimposed sine waves---they look like this [ouhk.edu.hk]. To figure out what sine waves make up an image, you do a Fourier Transform, which is well documented on Google.
Natural images contain a characteristic power spectrum: some frequencies--lower ones--tend to occur quite often, while others--higher frequencies--are less common. The spectrum is actually pretty regular across an image set. I'm betting, though, that fake images don't respect this power spectrum and lead to detectable anomalies.
But beware! You can have completely bogus images that also respect the power spectrum. Some researchers at MIT (Torralba et al.) use power spectra to successfully detect different image environments, e.g. indoors, outside in a city, out in the country, etc., but in the papers they show some images that have been reconstructed from their spectral models.
You would not be fooled. They look like finger paint pictures.
--Tom
Actually... (Score:5, Interesting)
The unfortunate thing (Score:5, Insightful)
Now that I have written that, looking around, it appears I am actually wrong. If you look at Mr. Farid's personal page, it appears he will be publically presenting [dartmouth.edu] a paper covering the fakeness-detection algorithm. I hope the full algorithm will be presented to the academic community.
and from the obvious paranoid side... (Score:2, Interesting)
Self Defeating (Score:5, Insightful)
Re:Self Defeating (Score:2)
Re:Self Defeating (Score:2)
Two things:
Re:Self Defeating (Score:2)
Unless it's shadow encryption. In that encryption it's 1 way.
Encryption is reversible, by definition. You're talking about hashing. Secure hashes are useful, but they're not encryption (at least not by themselves, you can combine a secure hash with some other techniques to make a reversible encryption algorithm that's likely to be reasonably good).
thats why breaking a UNIX pass by anything other than brute force is impossible.
Only as long as the hash truly is one-way. The only way to be complete
Re:Self Defeating (Score:4, Informative)
As for "almost unbreakable" - well, that simply means that it *is* breakable after all; brute force does work, even though it's usually inefficient (which is why I added that an attacker would need a sufficient amount of time, energy and/or computing power).
Furthermore, from what I know, it is neither proven that your average hash functions (MD5, SHA1, RIPEMD-160 etc.) are collision-free nor that the underlying mathematical problems of your average asymmetric ciphers (RSA, DS, El Gamal etc.) indeed cannot be solved with less effort than brute force. (I may be wrong here, so feel free to correct me)
And lastly... you missed my point completely.
Re:Self Defeating (Score:3, Funny)
Re:Self Defeating (Score:2)
Re:Self Defeating (Score:4, Interesting)
So much for my faked photo of Rumsfeld & Sadda (Score:5, Funny)
Rumsfeld was really shaking hands with an alien, and Saddam was shaking hands with Elvis, but the resulting merger of the two photos was much more provocative.
Re:So much for my faked photo of Nixon and Elvis (Score:2)
If you want to see the original of the Nixon Elvis photo, do a google image search on "Nixon meeting Elvis". And the original I got our faces from (gawd, this brings back memories) is here. [dimspace.com]
OT but sorta related (Score:2)
Just a thought... (Score:5, Insightful)
I wonder if they've considered the potential applications in image compression?
I had developed a foolproof algorithm... (Score:3, Funny)
don't believe the parent post since... (Score:3, Funny)
What kind of digitized photos does this work on? (Score:5, Insightful)
While this might not be a problem for gross manipulations (the faked John Kerry/Jane Fonda photo [sfgate.com] being a recent example) I can imagine a class of images where subtle manipulations caused great effects and were not readily distinguishable from compression artifacts.
Re:What kind of digitized photos does this work on (Score:2)
good way to get some pr for some uni though, people like magic like in some bad scifi where they can detect which areas are fake
Re:What kind of digitized photos does this work on (Score:2, Interesting)
Smudging a part of an image would remove these artifacts, and would be near impossible to reproduce - like the paper grain on a canvass oil painting.
Re:What kind of digitized photos does this work on (Score:5, Informative)
So good point. That does seem to be a problem. The NY Times article has more details than the other; it is worth reading.
Re:What kind of digitized photos does this work on (Score:3, Interesting)
One wonders whether this will lead to a legal distinction between lossily compressed images and others. While audiophiles have long been ape for lossless compression, not as much a need has been felt for graphics. Where do lossless graphic compression efforts stand? Is this an area where a proprietary standard might lead to big $$$?
Re:What kind of digitized photos does this work on (Score:3, Funny)
Re:What kind of digitized photos does this work on (Score:3, Insightful)
Re:What kind of digitized photos does this work on (Score:2)
Just a wild idea off the top of my head... while JPEG image compression is a lossy process, it's still a mathematically reproducible process. It might therefore be possible to exhaustively generate the set of originals that could be compressed to the image in question*. If you then apply the detection algorithm to the originals, none of them may pass and you'll still have a valid conclusion.
*
Random set of pixels? (Score:2, Interesting)
Re:Random set of pixels? (Score:2)
Another is film grain, not as prevalent in digital cameras, however, with film cameras, grain is varied based on film speed, manufacturer, light level, and other situation. When you comp together images from a variety of sources, one of
Okay, but here's my question. (Score:4, Interesting)
That makes sense. However, it seems like these statistics would be based on very minor details. What happens if you run their analyzer on an image that has been altered by using lossy image compression, such as JPEG compression? [conjoineddreams.net] Lossy image compression is designed to obliterate details humans wouldn't notice; some of these details might be significant to their statistical model. Would JPEG-compressing an image make it impossible to determine its veracity? Would their software just tag all JPEG images with compression below a certain threshold as being "unnatural" (since they have been, after all, digitally altered-- just not digitally altered in a content-relevant way...)
And don't some digital cameras use lossy formats such as JPEG as their native storage format?
Re:Okay, but here's my question. (Score:3, Interesting)
Re:Okay, but here's my question. (Score:3, Informative)
Re:Okay, but here's my question. (Score:2)
Re:Okay, but here's my question. (Score:2)
In a modern court, the defense doesn't have to prove that you've doctored the picture. If they can prove that you've run the image through three different encoders (rather than coming straight from the digital camera), they will likely establish reasonable doubt that the image is genuine.
Re:Okay, but here's my question. (Score:2)
Old Problem (Score:2)
Description / demo (Score:2)
Re:Description / demo (Score:2)
http://science.slashdot.org/comments.pl?sid=11559
It will improve the fakes (Score:3, Insightful)
But hey, I'm pretty sure this one pic of the Olsen twins I got from Kazaa is real anyway.
Re:It will improve the fakes (Score:2)
Re:It will improve the fakes (Score:2)
If we increase our understanding of image manipulating it will work both ways. If you know how to do something 'backwards' you'll also be in a better position to do it the other way around.
Why not *make* it real? (Score:3, Insightful)
Re:Why not *make* it real? (Score:3, Interesting)
The short answer is dot structure. All printers, (excepting Dye Sub) use some form of sparying of ink, or layering of screened images(halftone dots) Fancier does not necessarily mean smaller dots, it usually means more calibrateable and more consistent color. What you need is a film recorder, which will transfer your image to a negative or a slide, and currently, there are no digital cameras that will record an image at a high enough resolution for this to be flawless (ab
A more in-depth article (Score:5, Informative)
If I wanted to create photos/vids of a UFO (Score:2)
Re:If I wanted to create photos/vids of a UFO (Score:2)
I apologize for being so thick, but I'm not following you. Exactly what would be accomplished by doing this?
Re:If I wanted to create photos/vids of a UFO (Score:2)
it would be too simple to make a balloon that is too obviously trying to attract attention.
and since the ufo believers think they're so good at figuring out hidden stuff, i'd be playing right into their psyche.
MICHAEL, thanks for adding the . . . (Score:3, Informative)
Re:MICHAEL, thanks for adding the . . . (Score:4, Interesting)
If A doesn't conform to the statistical distribution of B, then A isn't B (with a high degree of confidence). But if does, that doesn't mean it is B -- you might just be looking at the wrong set of identifying features. I.e. not everything with two feet and a bill is an aquatic bird; it might be the waiter.
Re:MICHAEL, thanks for adding the . . . (Score:2)
I apologize for having phrased it poorly. My point is the following scenario . .
-- Mr.X is arrested for having child porn.
-- His defense (recently legitimized by the U.S. Supreme Court) is to say, "The images are digital artifice, no actual children were involved."
-- The prosecutor says, "We ran the images through Farid's process, and there's no evidence of alteration. The artifice which you claim is involved, wo
Re:MICHAEL, thanks for adding the . . . (Score:2)
Law enforcement applications (Score:2)
That's a good point. Hmm. Perhaps a free plugin for Photoshop/GIMP could be released and widely distributed that modifies an image to be in conformance with the model? That'd retain plausible deniability.
My first thou
light popularistic article (Score:2)
"With today's technology, it's not easy to look at an image these days and decide if it's real or not," says Farid. "We look, however, at the underlying code of the image for clues of tampering."
- Hany Farid
Farid's algorithm looks for the evidence inevitably left behind after image tinkering. Statistical clues lurk in all digital images, and the ones that have been tampered with contain altered statistics.
*****
doesn't really say anything beyond "hey we just look at the matrix code you'll see irregul
Re:light popularistic article (Score:2)
but it's still problematic because in the cases where you would need to be able to prove it to be a fo
practical use (Score:5, Funny)
Admissibility of Digital photographs as evidence? (Score:5, Interesting)
for those who want more information (Score:3, Informative)
NY Times Article Text (Score:2, Informative)
For Doctored Photos, a New Flavor of Digital Truth Serum By NOAH SHACHTMAN
Published: July 22, 2004
From the material found on his hard drive, Bryan Sparks of Springfield Township, Ohio, seemed guilty when he was arrested in 2002. The sexually explicit pictures of minors appeared to put him on the wrong side of child pornography laws. But at his trial this spring, Mr. Sparks was acquitted because no one could tell for sure whether the images were authentic or just clever
Over at the Whitehouse... (Score:2)
GWB: Lets just creatify some photographs of those Iraqi WMD
DR: Great plan Mr President
GWB : Dang! It won't work, they'll provify its a fake
DR: Not till after the election George... not till after the election.
More About Investigating Digital Images (Score:3, Informative)
good background and intro, little details (Score:3, Insightful)
That's pretty much all the detail on the method to detect image altering. Seems reasonable, but:
1) How many real photos deviate how far from the statistical "norm" (i.e., how likely are false positives when checking for alteration?)
2) How long before there are tools that can inject the proper (expected) statistical characteristics into a faked image?
These are not addressed in the article. Anyone have more info?
They detect resampling (Score:2)
I've looked at their scientific paper [dartmouth.edu] and their technique albeit not perfect seems to be very good in detecting any kind of resampling in the image (up- and down scaling, rotating, etc.). When you make the transformation on a grid, the interpolation creates some almost invisible artifacts and regular patters which they are able to find by their analysis. It's difficult to create forgieries without these kinds of ma
reverse-engineering? (Score:2, Interesting)
Using the fake picture scanner backwards gives.... (Score:2)
Time for a Genetic Algorithm? (Score:3)
re: "Embed a private key" -- ooh, GOOD question! (Score:2)
Actually, I don't think that'd work, but it raises a very interesting point:
when an UN-faked image is published with any kind of intentional alteration for legitimate purposes -- e.g., digital watermarking to protect the creator's copyright -- could that alteration have the unintended side-effect of making it impossible to prove that the ima
Details (Score:2)
("RTFP? I can't be bothered to RTFA!")
Only works if you don't know how to use Photoshop (Score:2)
Or, as artists say, "work big".
What this is not (or what it may not be) (Score:2)
This may not be the case. There are certainly some features that we are very good at recognizing when there is something wrong: like proportions and white balance changes. I mean we are very good at this so creating an algorhythm to do better than us would be very hard. However there are some feature
To all the people who think it's defeatable (Score:2)
1. I'd never say, "Gee, he's a professor, so let's all just trust him, because he must know what he's doing, right?" But people in his position do tend to be somewhat conservative about pre-publicity, to avoid later looking foolish and damaging their rep. In any case, that's why there's a peer-review process -- which is why I'd put a lot more faith in statements from him, than I would if they came directly from DHS.
2. In the
doesn't work with jpegs! (Score:2)
doesn't this make the technique almost useless?
Why not just run the process in reverse? (Score:2)
If you can identify why something looks fake, that information should imply a solution for non-fakeness.
Making Undetectable Faked Photographs Gets Easier (Score:2)
To preface, I don't belive this at all. Consider a photograph that has undergone a hue transformation, and is titled George W. Bush has blue face, see photo. It will have all the other properties of a real photo, but will be fake. Another example, consider a photograph of models.
But assuming this is possible, then I can make a fake photograph that is so convincing that they will belive it is true. First construct the photograph, and possibly include markings as to what are the edges of adjusted areas, etc
In one word... (Score:2)
Just like the "face recognition systems" used to spot terrorists [cio.com], or the "child protection" software that's supposed to recognise porn [dansdata.com].
Not only is the success rate well below 90%, but, more importantly, it spits out thousands of false positives.
And this is without even considering their admission that their technique does not work on JPEG images, even at "90% quality". In other words, they admit it won't work at all in 99% of digital pictures.
These are all tasks that need so much
Pop quiz (Score:2)
Bonus points if you answer the question without using the technique described in the article.
P.S I'm not claiming credit for it; it used to be on his website but isn't anymore.
Re:Pop quiz (Score:2)
Re:Pop quiz (Score:2)
Embed a GPS! (Score:2)
There are security details, but if it is possible to tag an image with WHERE it was taken in a secure fashion, it would eliminate all but the most enterprising forgers.
Not happening... (Score:2)
Our hope, however, is that as more authentication tools are developed it will become increasingly more difficult to create convincing digital forgeries
Whos to say if a certain method is the right method to use? Just like there are numerous viruses, anti-viruses, and anti-anti-viruses; I think its safe to say there will photo manipulation software, counter-photo manipulation software, and counter-counter-photo manipulation software. Course this leads to programs being compromised
from the author (Score:3, Informative)
sp04.html [dartmouth.edu]
ih04.html [dartmouth.edu]
sacv03.html [dartmouth.edu]
And, we have two new papers currently in review (abstracts are currently on-line, and preprints will be available soon):
sp05a.html [dartmouth.edu]
sp05b.html [dartmouth.edu]
Some of these techniques work, as some have pointed out, only on high-quality jpeg or uncompressed images, while others work on lower-quality images. We are only in the early stages of development, and are currently working to extend some of these ideas to low-quality jpeg and gif images (though this will likely be a harder problem given that the compression artifacts will overwhelm any statistical perturbation resulting from tampering). One outcome of this may be that a legal standard is set that enforces images brought into a court of law to be of a certain resolution and compression quality.
I will be the first to admit that each of the techniques that we have developed can be reverse-engineered, though doing so is more difficult for some techniques than others. It is our hope, however, that as we and others continue to develop more techniques it will become increasingly more difficult (though never impossible) to simultaneously foil each of the detection tools.
Doesn't work on .jpg's (Score:3, Informative)
And, "Professor Farid said that for now the technique does not work as well with files created in JPEG, the compressed picture format most commonly used online. As the size of a JPEG file shrinks, the correlations between pixels become much less obvious. 'At 90 percent quality, it falls apart very quickly," Professor Farid noted.'"
Re:huh? (Score:2)
Re:huh? (Score:2)
The Pixels are not stretched, they remain squares, the color is inteigently manipulated by Photo Shop or whatever, but the pixels are not moved.
The picture on a digital medium would be a perfect replica (or almost perfect for lossy compression) of what you were working on.
The 'pixel constructin' is refering to the way that the colors are aranged on the image, particularly on the edges of objects. These colors, and their locations will transfer to paper, jpeg, gif, etc. So long as the replica is of suit
Re:huh? (Score:2)
Re:Utterly Devoid of Content (Score:2)
Re:"omg alien pics pls" (Score:2)
If you're referring to the saucer-over-SF image, why don't you inquire at info@WholeEarthMag.com ?
Re:Embed a private key in the camera? (Score:2)
The real drawba
Re:Embed a private key in the camera? (Score:2)
If a camera manufacturer were to do this in a *secure* manner, it would be quite expensive. The 'signing' silicon would have to be on the same silicon as the CCD element otherwise it would be vulnerable to a simple attack where someone feeds the already doctored image in by (for example) creating a FPGA which looks like the CCD element and interfaces to some data source.
But I was thinking... What would prevent against a 'old-fashioned' fakery? Imagine getting a good high-resolution image of Bin Laden and B
Re:So... (Score:2)
Unfortunately (?), the process doesn't work on JPEGs, according to the NYT article.
Re:Legal issue (Score:2)
- raytracing/3D rendering software will become illegal . .
Well, you're HALF-right, when you say "current"; but whether your prediction comes to pass, depends greatly on what happens in the coming November election. If we can get rid of Inspector Javert -- err, excuse me, Attorney General John Ashcroft -- then there's hope for improvement.
But the problem isn't only in the USA. From