Though facial recognition software has been in our homes for some time (having been a feature in Picasa and iPhoto since 2009), the prospect of being the unwitting subject of similar technology while out and about is an alien one. That could be about to change thanks to the announcement of OptimEyes, a system designed to be fitted to digital advertising hoardings in Europe to gauge just who is paying attention.

Developed by "audience measurement" specialists Quividi (literal translation from Latin: I saw that) for advertising company Amscreen, OptimEyes won't, Amscreen says, identify individuals, but instead be used to gauge the number and type of people paying attention to particular adverts. This will "provide an even greater understanding into the effectiveness of any given advert across our entire network," the company writes.

Amscreen says that the system, which, unsurprisingly, requires the integration of a camera, will gauge the number of possible viewers and compare it with the actual number of viewers, as well as their age and gender. The system will also log the time and location of each view. And because this data will be reported live, Amscreen suggests it raises the possibility to optimize a marketing campaign mid run.

So will these all-seeing advertisements be easy to spot? "Basically they're a webcam," Amscreen's Marketing Director Mike Hemmings, told Gizmag. "It will not be obvious there's a camera there. There'll be no glaring light." But Hemmings describes the system more as a facial identification system rather than a recognition one, gauging the darker areas of a face to estimate age (with accuracy in the high 80s, percentage wise, he says). Gender, meanwhile, is "guessed" on the basis of attributes such as hair length.

Part of Alan Sugar's empire, Amscreen controls some 6,000 digital advertising screens in Europe. Hemmings told Gizmag that the intention is to install the OptimEyes system across the company's entire installed base in the UK, Germany and Switzerland, with screens to follow in France and Oman.

Amscreen expects to announce advertising partners in the next few months, but as to when these screens will appear in our streets … "We've been testing for a good year now," Hemmings says.

So, if you live in any of the above countries, the next time you gawp at an advertising hoarding, there's a slim possibility that it's gawping back. Qui vidi? Quod eram visus, more like.

Amscreen's promotional video is below.

Source: Amscreen, via Mashable