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The software also seeks out areas in photographs where applications like Adobe Photoshop fill in pixels. Every time the photos get mashed together, some modification of one or both of the images is required. Sometimes one person is blown up in size while a second might be rotated slightly. These changes leave empty pixels in the frame.
Photo-retouching applications use probability algorithms to fill in those pixels with colors and imagery and thus make them look realistic. Conversely, Farid's software employs probability to ferret out which of these fringe pixels are fill-ins.
"We're asking, from a mathematical and statistical perspective, can you quantify the manipulation," he said. "There are statistical correlations that don't occur naturally."
The quality of forgeries and touch-up jobs varies widely, but it continually improves. Farid gets consulting requests all the time. Some people call him to see if a photo of an item on eBay has been retouched. Others want advice on the genuineness of photos from online dating services. The Image Science Group has also collaborated with the Metropolitan Museum of Art in New York to determine if certain drawings were actually made by Flemish painter Bruegel or were forgeries.
One of the most recent celebrated cases of fraud--South Korean scientist Hwang Woo-suk's claim that he cloned stem cells--actually didn't need specialized software. Spots and artifacts in the background visible to the naked eye showed that the images of cells that came from the supposedly cloned dog were duplicated, Farid noted.
Farid's interest in fraud detection is somewhat random. As a post-doctoral student at MIT seven years ago, he was meandering through the library looking for something to read. He grabbed the Federal Rules of Evidence, a compendium of laws governing the admission of evidence in trials in federal court.
The rules, at the time, allowed digital images of original photographs to be admitted in court as long as they accurately reflected the original. The footnotes that accompany the rules, however, acknowledged that manipulation was a problem and that government did not yet have a way to deal with it.
When Farid started researching the scientific literature, he found little on fraud detection in digital imagery.
Will you be able to get a copy of the Java-based version of the Image Science Group's applications? Probably not. One of the dilemmas of this type of software is that the more widespread the distribution, the more chance forgers will exploit it to their advantage. Police organizations and news media outlets will likely get access to the application, but he's still unsure of how far he will extend distribution beyond that.
And although Farid charges a fee when asked to serve as a consultant, the software will be made freely available under an open-source license. He doesn't even have plans to form a company around his work. A significant amount of the research, after all, was funded by federal grants.
"Taxpayers," he said, "are paying me to do this research and it needs to go back out."
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evidence in court. A good digital artist could doctor a photo to
make anything look real
evidence in court. A good digital artist could doctor a photo to
make anything look real
- Photos as evidence in court.
- by steelsmith80 March 10, 2008 2:36 PM PDT
- I know that VeriPic makes photo management software that can authenticate photos from the camera level. They are in use mostly in law enforcement for evidence photos. I have worked with the system before and know that the software is in court all the time. I hope that helps. Here is their website: http://www.veripic.com
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