Skip to comments.
Identifying Manipulated Images: New tools that analyze the lighting in images help spot tampering
Technology Review (MIT) ^
| March 17, 2008
| Erica Naone
Posted on 03/17/2008 11:15:29 AM PDT by Stoat
Identifying Manipulated Images
New tools that analyze the lighting in images help spot tampering. By Erica Naone
|
True or false? The tool used above spots whether an image has been manipulated by modeling the lighting in the image based on an analysis of visible surfaces. To analyze an image, a user indicates the surfaces to consider using contour lines (shown above in white). The system checks for inconsistencies in the way that those surfaces are lit. Credit: Micah Kimo Johnson, Hany Farid |
Photo-editing software gets more sophisticated all the time, allowing users to alter pictures in ways both fun and fraudulent. Last month, for example, a photo of Tibetan antelope roaming alongside a high-speed train was revealed to be a fake, according to the Wall Street Journal, after having been published by China's state-run news agency. Researchers are working on a variety of digital forensics tools, including those that analyze the lighting in an image, in hopes of making it easier to catch such manipulations. Tools that analyze lighting are particularly useful because "lighting is hard to fake" without leaving a trace, says Micah Kimo Johnson, a researcher in the brain- and cognitive-sciences department at MIT, whose work includes designing tools for digital forensics. As a result, even frauds that look good to the naked eye are likely to contain inconsistencies that can be picked up by software. Many fraudulent images are created by combining parts of two or more photographs into a single image. When the parts are combined, the combination can sometimes be spotted by variations in the lighting conditions within the image. An observant person might notice such variations, Johnson says; however, "people are pretty insensitive to lighting." Software tools are useful, he says, because they can help quantify lighting irregularities--they can give solid information during evaluations of images submitted as evidence in court, for example--and because they can analyze more complicated lighting conditions than the human eye can. Johnson notes that in many indoor environments, there are dozens of light sources, including lightbulbs and windows. Each light source contributes to the complexity of the overall lighting in the image. Johnson's tool, which requires an expert user, works by modeling the lighting in the image based on clues garnered from various surfaces within the image. (It works best for images that contain surfaces of a fairly uniform color.) The user indicates the surface he wants to consider, and the program returns a set of coefficients to a complex equation that represents the surrounding lighting environment as a whole. That set of numbers can then be compared with results from other surfaces in the image. If the results fall outside a certain variance, the user can flag the image as possibly manipulated. Hany Farid, a professor of computer science at Dartmouth College, who collaborated with Johnson in designing the tool and is a leader in the field of digital forensics, says that "for tampering, there's no silver button." Different manipulations will be spotted by different tools, he points out. As a result, Farid says, there's a need for a variety of tools that can help experts detect manipulated images and can give a solid rationale for why those images have been flagged. |
|
|
|
Neal Krawetz, who owns a computer consulting firm called Hacker Factor, presented his own image-analysis tools last month at the Black Hat 2008 conference in Washington, DC. Among his tools was one that looks for the light direction in an image. The tool focuses on an individual pixel and finds the lightest of the surrounding pixels. It assumes that light is coming from that direction, and it processes the image according to that assumption, color-coding it based on light sources. While the results are noisy, Krawetz says, they can be used to spot disparities in lighting. He says that his tool, which has not been peer-reviewed, is meant as an aid for average people who want to consider whether an image has been manipulated--for example, people curious about content that they find online. Cynthia Baron, associate director of digital media programs at Northeastern University and author of a book on digital forensics, is familiar with both Krawetz's and Farid's work. She says that digital forensics is a new enough field of research that even the best tools are still some distance away from being helpful to a general user. In the meantime, she says, "it helps to be on the alert." Baron notes that, while sophisticated users could make fraudulent images that would evade detection by the available tools, many manipulations aren't very sophisticated. "It's amazing to me, some of the things that make their way onto the Web and that people believe are real," she says. "Many of the things that software can point out, you can see with the naked eye, but you don't notice it." Johnson says that he sees a need for tools that a news agency, for example, could use to quickly perform a dozen basic checks on an image to look for fraud. While it might not catch all tampering, he says, such a tool would be an important step, and it could work "like an initial spam filter." As part of developing that type of tool, he says, work needs to be done on creating better interfaces for existing tools that would make them accessible to a general audience.
|
|
|
|
TOPICS: Business/Economy; Miscellaneous; News/Current Events; Technical
KEYWORDS: fauxtography; manipulation; photographs; photography; photoshop; photoshopping; tech; techping
Navigation: use the links below to view more comments.
first previous 1-20, 21-40, 41-43 next last
To: SengirV
I hope they take a historical look at all of APs evil Israel/pro-Palestinian photos.Around the time they start doing something like that, the techs who run the photo analysis software will find their homes randomly blowing up......
21
posted on
03/17/2008 11:57:09 AM PDT
by
Stoat
(Rice / Coulter 2012: Smart Ladies for a Strong America)
To: Stoat
22
posted on
03/17/2008 12:03:32 PM PDT
by
Publius6961
(MSM: Israelis are killed by rockets; Lebanese are killed by Israelis.)
To: Stoat
Good! Now we can find out if all those Loch Ness pictures are real or not.
To: Stoat
Dan Rather is scared sh*tless because he's heard there's a version in beta that can do the same for news broadcasters...
24
posted on
03/17/2008 12:31:28 PM PDT
by
Dr.Zoidberg
(Mohammedanism - Bringing you only the best of the 6th century for fourteen hundred years.)
To: Stoat
Fakers will just use this software on their productions to see if it passes the test.
If it fails, they will work a little longer until it passes.
Also, this sort of logic can be incorporated into image-processing software so that it will flag anything that is inconsistent.
Big breakthrough? No.
To: Stoat
Sometimes, it takes an expert...
To: reagan_fanatic
LMAO! Is that a half-eaten bagel flying out of his mouth?
Or a half-eaten bagel being thrown at him?
“snicker”
27
posted on
03/17/2008 1:12:14 PM PDT
by
Stoat
(Rice / Coulter 2012: Smart Ladies for a Strong America)
To: rdb3; Calvinist_Dark_Lord; GodGunsandGuts; CyberCowboy777; Salo; Bobsat; JosephW; ...
28
posted on
03/17/2008 5:33:18 PM PDT
by
ShadowAce
(Linux -- The Ultimate Windows Service Pack)
To: reagan_fanatic; Stoat; mikrofon; Charles Henrickson
Analyze *this*.
29
posted on
03/17/2008 5:37:55 PM PDT
by
martin_fierro
(I'M NOT DEAD YET!)
To: dead
30
posted on
03/17/2008 5:38:35 PM PDT
by
The Spirit Of Allegiance
(Public Employees: Honor Your Oaths! Defend the Constitution from Enemies--Foreign and Domestic!)
To: martin_fierro; dead; Tijeras_Slim; mikrofon; PJ-Comix
I dunno, something strikes me funny about this photo. . . .
To: martin_fierro; mikrofon
This one, too, like somehow it's been . . . oh, manipulated. . . .
To: Charles Henrickson; martin_fierro
"I have never .. tampered .. with any .. photos -- Mr Henrickson..."
33
posted on
03/17/2008 6:50:25 PM PDT
by
mikrofon
(*CERTIFIED* Original)
To: martin_fierro
Analyze *this*.LMAO
It actually doesn't take a whole lot of stretching and manipulation to get ol' Waxman to change from his 'normal' ghoulish self into a full-fledged gargoyle, does it?
hehe
34
posted on
03/17/2008 6:58:10 PM PDT
by
Stoat
(Rice / Coulter 2012: Smart Ladies for a Strong America)
To: ShadowAce
Thank you very much for pinging your list :-)
35
posted on
03/17/2008 6:59:30 PM PDT
by
Stoat
(Rice / Coulter 2012: Smart Ladies for a Strong America)
To: Stoat
Darn, why did JimRob kick Registered out of Free Republic when we needed him the most?
Can you guess what he would do with this subject?
36
posted on
03/17/2008 7:01:48 PM PDT
by
Hunble
To: martin_fierro
Now that’s no way to treat a perfectly good Bat Boy.
37
posted on
03/17/2008 7:04:19 PM PDT
by
JoJo Gunn
(Help control the RINO population. Have them spayed or neutered. ©)
To: Hunble
Darn, why did JimRob kick Registered out of Free Republic when we needed him the most? Well, his last post sums it up and he asked for his account to be closed.
Posts by Registered
Can you guess what he would do with this subject?
Although it's always a shame when talented, artistic people leave for any reason, I think that we have a number of currently active and spectacularly talented Image Wizards who keep us laughing while we're being informed....several have honored us by posting to this thread
38
posted on
03/17/2008 7:15:27 PM PDT
by
Stoat
(Rice / Coulter 2012: Smart Ladies for a Strong America)
To: Stoat
Now lets be a little more honest here....
JimRob and Registered were fighting because he supported Rudy Giuliani. You know it, and I know it.
What a horrible waste of an outstanding talent!
As we look back, that argument sounds so silly now.
39
posted on
03/17/2008 7:28:01 PM PDT
by
Hunble
To: Stoat
Now lets be a little more honest here....
JimRob and Registered were fighting because he supported Rudy Giuliani. You know it, and I know it.
What a horrible waste of an outstanding talent!
As we look back, that argument sounds so silly now.
40
posted on
03/17/2008 7:28:26 PM PDT
by
Hunble
Navigation: use the links below to view more comments.
first previous 1-20, 21-40, 41-43 next last
Disclaimer:
Opinions posted on Free Republic are those of the individual
posters and do not necessarily represent the opinion of Free Republic or its
management. All materials posted herein are protected by copyright law and the
exemption for fair use of copyrighted works.
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson