National Institute of Informatics, Japan in co-operation with Sharp, has developed a technique to render any recording unwatchable by flashing pulses of infra-red (IR) light from behind the cinema screen. The pulses pass through tiny holes in the screen originally designed to allow through sound, and cause interference to any video cameras held by members of the audience. The IR light, while invisible to human eyes, is also impossible to filter out without rendering the recording too blurry to watch. The team says best results are achieved at a speed of 10 pulses per second.

Films screened at cinemas are already digitally watermarked to prevent them from being copied digitally, but there has been no way of reliably stopping pirates from recording films using video cameras. The damage caused by bootleg film recordings is estimated at around 3 billion dollars a year, according to the American Film Institute.