Reversible watermarking for digital images

Jul 06, 2010

Every picture tells a story, but how do you know that a digital photo has not been manipulated to change the tale being told? A new approach to adding an encrypted watermark to digital images allows the an image to be validated against a pass key, according to research published in the International Journal of Signal and Imaging Systems Engineering.

Visible watermarks are routinely added to as a form of copy protection, but their presence essentially destroys the picture, obliterating information within altered pixels in a way that cannot be reversed. Now, Dakshinamurthi Sivakumar and Govindarajan Yamuna of Annamalai University, in Tamil Nadu, India, have developed a new, reversible watermarking scheme. The system could be used initially for the authentication of military images.

Inexpensive image editing software is now available that can be used to make essentially undetectable "photo realistic" changes to almost any photograph, the team explains. In a military setting it is important to prevent unauthorized manipulation of digital images and to be able to demonstrate credibility and provenance.

"Traditionally, source authentication and integrity verification of digital data have been carried out with and encrypted watermarks," the team says, "Unfortunately, watermarking techniques modify original data as a modulation of the watermark information and unavoidably cause permanent distortion to the original data." Reversible, or lossless, watermarking is therefore required for many highly sensitive applications.

The team has now developed a reversible watermarking system based on calculating the parameters of every pixel in the image but nevertheless at low computer power. This information is converted into a code, a Hash Message Authentication Code (HMAC), of the image where distinct pixel values are selected for embedding watermark bits and the preferred pixel values are stored as a key. The key thus generated is used for both the watermark extraction and restoration of the original image. The extracted HMAC and the HMAC of the restored image can be compared to verify that the received image is authentic and has not been altered.

Explore further: Scientists track Internet usage as it pulses across the globe daily (w/ Video)

More information: "Novel reversible watermarking scheme for authentication of military images," Int. J. Signal and Imaging Systems Eng, Vol. 2, 134-140

add to favorites email to friend print save as pdf

Related Stories

Scuppering pirates improves internet audio

Aug 09, 2007

A new digital watermarking system not only protects music and media files from online pirates but also ensures that the quality for legitimate users is as good as it gets.

Researchers detect secret files lurking within digital images

May 24, 2006

Keeping computer files private requires only the use of a simple encryption program. For criminals or terrorists wanting to conceal their activities, however, attaching an encrypted file to an e-mail message is sure to raise ...

Investigating Digital Images; What's real and what's phony?

Jul 01, 2004

''Seeing is no longer believing. Actually, what you see is largely irrelevant,'' says Dartmouth Professor Hany Farid. He is referring to the digital images that appear everywhere: in newspapers, on Web sites, in advertising, ...

Robust watermarking offers hope against digital piracy

Dec 05, 2008

(PhysOrg.com) -- Watermarks have been used for centuries to prove the authenticity of bank notes, postage stamps and documents. Now European researchers are considering them as a new tool in the fight against digital piracy ...

Encryption, data hiding and watermarking

Dec 06, 2004

Terrorists might use it to mask their messages: it's called data hiding - the subject of a new book by Ali Akansu, PhD, professor of electrical and computer engineering at New Jersey Institute of Technology (NJIT). Akansu's boo ...

Recommended for you

Samsung phones cleared for US government use

38 minutes ago

Samsung Electronics Co. said Tuesday some of its Galaxy mobile devices were approved by the National Security Agency for use with classified U.S. government networks and data, a boost to the company's efforts to expand in ...

Amazon, Simon & Schuster sign book retail deal

1 hour ago

Amazon has reached a deal with American book publisher Simon & Schuster, the companies said, though the e-commerce giant remains at loggerheads with France's Hachette over e-book pricing.

Review: Apple Pay in action

2 hours ago

If there ever comes a day I can ditch my wallet and use my phone to pay for everything, I'll look back to my first purchase through Apple Pay: a Big Mac and medium fries for $5.44. That wallet-free day won't ...

User comments : 0