If you've ever been to Tokyo or any other large Japanese city, you'll have noticed the huge variety of billboards plastering the urban landscape, often featuring the month's most popular idol. Now researchers at Keio University are working on a system that will allow passers-by to interact with said posters via an ultrasound sensor setup. The sensor will detect the motion of people in front of it, and display appropriate pictures in response — "appropriate" may not be the right word for everyone, though, as the main use case demonstrated by the researchers so far is the ability to "kiss" the idol on screen. After you've expressed your affection for the poster and moved your head away, the girl blushes with embarrassment, for example.

The team plans to implement its recognition technology in an iPad app first of all, and is upbeat about the prospect of attracting attention:

"We think we could get pop idols to actually pose for this, and sell it as an application, or it could be used in digital signage. I think people would be really attracted by a face that gives a kiss as they walk past."