Shadows and light: Researchers develop new software to detect forged photos

Aug 05, 2013

Dartmouth and UC Berkeley researchers have developed new software to detect faked photos, using a geometric algorithm to locate inconsistent shadows that are not obvious to the naked eye.

The new method is a significant step in the field of digital forensics, which national security agencies, the media, and others use to differentiate between authentic images and computerized .

The study, titled "Exposing Photo Manipulation with Inconsistent Shadows," was presented last week at the Association for Computing Machinery's SIGGRAPH conference and is to be published in the journal ACM Transactions on Graphics in September.

The new forensic method analyzes a variety of shadows in an image to determine if they are physically consistent with a single illuminating light source. This allows a forensic analyst to determine if a photo is physically plausible or the result of image fakery. This method has, for example, debunked the claims that the lighting and shadows in the famous 1969 photo are fake.

"Our method shifts the dialogue from 'does the lighting/shadow look correct?,' which is well known to be highly unreliable, to a discussion of whether an analyst has correctly selected the location of cast and attached shadows in an image, a far more objective task," says senior author Hany Farid, a professor of computer science and head of the Image Science Group at Dartmouth. "In this regard, our method lets humans do what computers are poor at—understanding scene content—and lets the computer do what humans are poor at—assessing the validity of geometric constraints."

Explore further: Disney researchers reconstruct detailed 3D scenes from hundreds of high-resolution 2D images

More information: www.cs.dartmouth.edu/farid/downloads/publications/tog13/tog13.pdf

Related Stories

Scientist finds telltale noise in altered photos

Jun 26, 2012

(Phys.org) -- University at Albany Computer Scientist Siwei Lyu and colleagues, working in partnership with the New York State Center for Information Forensics and Assurance (CIFA), have identified a ...

Space Image: Beside a giant

Feb 29, 2012

(PhysOrg.com) -- Saturn's largest moon, Titan, looks small here, pictured to the right of the gas giant in this Cassini spacecraft view.

Curiosity Mars Rover Gleams in View from Orbiter

Jul 25, 2013

An image from NASA's Mars Reconnaissance Orbiter released today shows NASA's Curiosity Mars rover and the wheel tracks from its landing site to the "Glenelg" area where the rover worked for the first half ...

Recommended for you

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

indio007
1 / 5 (2) Aug 06, 2013
All hype.
"This method is intended for use where there is only a single dominant light source. While this limitation does preclude analysis of scenes lit by multiple point lights or diffuse area lighting, it includes the common situation of outdoor scenes lit by the sun or indoor scenes photographed with a flash."

More news stories

Under some LED bulbs whites aren't 'whiter than white'

For years, companies have been adding whiteners to laundry detergent, paints, plastics, paper and fabrics to make whites look "whiter than white," but now, with a switch away from incandescent and fluorescent lighting, different ...

Researchers uncover likely creator of Bitcoin

The primary author of the celebrated Bitcoin paper, and therefore probable creator of Bitcoin, is most likely Nick Szabo, a blogger and former George Washington University law professor, according to students ...

The importance of plumes

The Hubble Space Telescope is famous for finding black holes. It can pick out thousands of galaxies in a patch of sky the size of a thumbprint. The most powerful space telescope ever built, the Hubble provided ...