Facial recognition startup Viewdle on Wednesday began letting Android smartphone users see which of the people around them are vampires and which are vampire slayers.

A "Third Eye" augmented reality game released by the San Francisco company online at viewdle.com is the first installment in a trilogy that will culminate in a battle between the undead and defenders of the living.

It was also intended as a fun demonstration of a powerful software platform that lets smartphone cameras recognize what they see and potentially support services such as sight for the blind or memories for the forgetful.

"It is true science fiction on some level," Viewdle chief product officer Jason Mitura told AFP. "The way people use their devices to interact with the world is going to change dramatically."

At the heart of the vampire-themed game is Viewdle's facial recognition technology that debuted in April in the form of a SocialCamera application for Android-powered smartphones.

SocialCamera uses computer algorithms to create "faceprints" that people can tag with names and store in smartphones. The software then matches faceprints to subjects in subsequent photos.

Android smartphones can instantly connect names to those in photos and share the images using social networking service Facebook, photo-sharing website Flickr, or by email or instant message.

"Third Eye" uses facial characteristics to evaluate whether people viewed through smartphone cameras are "blood suckers" or humans who can be recruited as vampire slayers.

The objective of the first part of the game is to amass an army and establish alliances for battles between clans that will play out in installments due for release later this year.

"The gaming mechanism forces play that requires people to interact with the real world," Mitura said. "You hold the smartphone up to an object and it triggers game play; in this case the object is a person."

Viewdle has avoided controversy by putting the facial recognition power in smartphones with users keeping control, instead of putting the information on servers in the Internet "cloud."

Viewdle is working with chip and smartphone makers that are building computer vision into their offerings.

Viewdle bills itself as the leading independent facial recognition company for consumer gadgets. Its technology is developed by the company's research team in the Ukraine.

Viewdle is the result of 15 years of research, rooted in work done at The Cybernetics Institute in Kiev, and got its first infusion of investor money -- 2.5 million dollars -- in June 2008.

High-powered players in September pumped $10 million into the Palo Alto, California, startup devoted to crafting ways to let smartphones "see" things the same way people do.

The influx of cash came from Qualcomm, BlackBerry Partners Fund, US electronics retail chain Best Buy, and Anthem Venture Partners, an investment firm that has backed Viewdle from the outset.

"We are giving smartphones human eyes," Viewdle co-founder and chief executive Laurent Gil told AFP.

"Letting them see the world the way people do... it is artificial intelligence," he said. "It is happening."

Viewdle plans to make a software developers kit available to gadget makers interested in building computer vision into devices.

"It is an exciting future for computer vision," Mitura said.