A "privacy visor" that uses infra-red light to interfere with facial recognition technology has been developed in Japan for people worried about being spotted by computers.

The goggles are useful for anyone who wants to avoid their identity being detected by hidden cameras, the inventors say.

"Measures for preventing the invasion of privacy caused by photographs taken in secret... are now required," said Isao Echizen of Tokyo's National Institute of Informatics.

The goggles, which are made of clear plastic, have lines of lights that emit near infra-red rays. Echizen says this is enough to throw software off the scent, rendering a face invisible to a computer.

However, the large plastic structures, complete with glowing lights and a sizeable power pack, may make the wearer somewhat conspicuous to the naked eye.

But, says Echizen, he believes they are an improvement on previous attempts at privacy shields -- or the less innovative sunglasses and baseball hat approach -- that created a barrier between people by obscuring their faces.

Last year, the European Union ordered Facebook to remove a facial recognition service after complaints from users about data protection.