U. ILLINOIS (US)—Most moviegoers catch the previews but miss the invisible “feature” playing on screen—an anti-piracy digital fingerprint that stamps the individual theater showing the motion picture.
Digital fingerprinting “actually is used a lot in movie theaters,” says Pierre Moulin, professor of electrical and computer engineering at the Beckman Institute and the Information Trust Institute at the University of Illinois. “You can’t see it, you just see the movie and you don’t even know it has a fingerprint.”
Moulin describes a digital fingerprint as “an invisible pattern superimposed onto the image, in the case of image fingerprinting, or an inaudible pattern, in the case of audio.”
Recent estimates suggest film piracy costs the industry more than $6 billion a year, with more than 80 percent of the piracy taking place overseas. Moulin says modern movie piracy often involves recording with a high-quality camcorder in a movie theater that has been pre-arranged to include only the one doing the filming and the projectionist.
He says that once a pirated DVD is obtained, then the question becomes how to extract the digital fingerprint from it. That’s where Moulin’s work comes in. He has developed applications for extracting digital fingerprints currently in use worldwide.
“These techniques are being used right now and in fact they catch people this way,” he explains.
“My research in the field started with developing a mathematical theory for those problems. It’s a pretty big field so it took a number of years,” he says.
“Based on the mathematical theory, then one can construct algorithms or methods which can be shown to be nearly optimal, where it’s almost impossible to improve them. There is only so much you can hide, with the requirements that it should be invisible and also detectable.”
Hiding information such as digital fingerprints in a movie and extracting that information when the need arises is the key focus of work in information forensics.
“It is a field that is quite multidisciplinary because it addresses issues that pertain to content of images and video and how you present them efficiently, and also to coding techniques and information theory,” Moulin says. “There are several fields that are essential to doing this kind of work.”
University of Illinois/Information Trust Institute news: www.iti.illinois.edu/