By letting consumers know the watermarks are there, even if they can't see them, Thomson hopes to discourage piracy without putting up obstacles to activities widely considered fair use, such as copying video for use on another device in the home or while traveling to work.

"The idea is to slow down piracy without limiting the use of the consumer. They should not be upset about this unless they are widely redistributing content," said Pascal Marie, responsible for strategic marketing at the company's content security division.

Thomson developed the technology, NexGuard, to identify individual copies of the films distributed digitally to cinemas or on DVD as preview copies for reviewers and awards juries. In the past, pirated copies of films available over the Internet or in street markets have been traced back to such sources.

Now, the availability of high-definition video-on-demand services is multiplying the points at which high-quality video can be pirated.