Tiny details in an image, for instance, may be too similar to have occurred naturally, suggesting a cut-and-paste maneuver. Or the color patterns may be too "normal" — beyond the limitations of sensors on digital cameras.

A growing number of researchers and companies are looking for such signs of tampering in hopes of restoring credibility to photographs at a time when the name of a popular program for manipulating digital images has become a verb, Photoshopping.

Story continues below ↓

Adobe Systems Inc., the developer of Photoshop, said it may incorporate their techniques into future releases.

"There's much more awareness and much more skepticism when (people) are looking at images," said Kevin Connor, a senior director of product management at Adobe. "That's why we think that's something we need to get involved in. It's not healthy to have people be too skeptical about what they saw."

Meanwhile, camera maker Canon Inc. sells a data-verification kit with some models. It can stamp digital photos with an invisible, mathematical summary of the image, such that even one tiny change will produce a mismatch and flag the photo as an alteration.

These techniques are of interest to law-enforcement officials and defense attorneys because photographic evidence can make or break cases. News organizations also have been increasingly exploring ways to spot hoaxes.

Not everyone is on board, however.

Michael Cherry, vice chairman of the Digital Technology Committee at the National Association of Criminal Defense Lawyers, said too little is known about the nuances of digital photography to put much trust in such detection techniques.

For example, Cherry said, using a photo printer rather than a laser printer can make a color image look nicer but lose details, such that a gun appears slightly off. The detection tools would reveal nothing, he said, because the photo itself was never digitally tweaked.

Click for related content

Tracking codes in color laser printers cracked
Can you make too many digital memories?
Digital scan detects hues in Leonardo piece

Meanwhile, enhancements to bring out details, such as sharpening a fuzzy surveillance image, may inadvertently turn a dark spot into something that looks like a gun.

And when there is intent to deceive, people who have enough money, time and skills can cover their tracks and evade any tamper detection, he said.

CONTINUED: "We are trying to make it harder for people ..."

1 | 2 | Next >

Rate this story

Low

High

• View Top Rated stories