Movie pirates who steal films by taping them while they are being screened in cinemas could be thwarted by new technology.

US company Cinea is working on a system that will manipulate the light levels of digitally screened movies.

The shifting light levels will go unnoticed by the audience, but will foil attempts to tape the film using digital cameras.

The company has won a $2m grant to develop a prototype from the US National Institute of Standards and Technology.

Sight unseen

Many pirate versions of popular films are created by people smuggling digital video cameras into movie theatres to record a screening of the film.

Often these pirate versions go on sale on video tape at the same time as the movie is showing in cinemas.

But the move from film to digital screenings of movies could mean that this method of piracy soon dies out.

Toy Story II was one of the first films to be digitally screened

One of the first films to be screened in this way was Toy Story 2, which was played from a computer hard disk rather than projected using 35mm film.

Virginia-based Cinea believes that this gives film studios an opportunity to stamp out camcorder piracy.

Cinea is working on a way to shift the light levels used to project the digital film that foils attempts to capture it on video.

Although the human eye would be unable to spot the shifting light levels, digital video cameras, which refresh what they see much more quickly than humans, would struggle to record a watchable image.

Cinea has won a grant to develop its system further and hopes to have a prototype ready within two years.

Currently there are few cinemas that are showing digital versions of films, and the numbers that can do so are not expected to rise significantly by 2004.

However, Cinea claims that eventually it will be able to cut film piracy by 50%.