Blippar wants your face in its app Rory Cellan-Jones

Technology correspondent

@BBCRoryCJon Twitter Published duration 6 December 2016

media caption WATCH: App recognises Rory

Ever seen someone across a crowded room and struggled to remember who they are? Well now there's an app which would allow you to fit the face to a name.

Blippar, the augmented reality business, is adding facial recognition to its app. Some will find that cool, others will see it as a creepy invasion of privacy.

At the moment the Blippar app gives you information about all kinds of objects when you point your smartphone's camera at them - it will identify famous paintings for example, or provide advertising content when you point it at a product.

Now the app will also recognise people - in real life or in photos and videos.

Blippar's co-founder Omar Tayeb gave me a demonstration, pointing the app at magazine pictures of Michael Fassbender and Hillary Clinton, then at a TV interview with Boris Johnson. In each case, the app recognised the faces and provided information about them - their social media profiles and Wikipedia entries.

image copyright Blippar image caption Blippar hopes members of the public will add their own faces to its database

He explained that Blippar had made more than 70,000 "public figures" recognisable by the app. I was rather surprised when he pointed the phone at me to find I was among them.

Users will soon be able to upload their own faces.

Here is where some people will feel uneasy. Do you like the idea that a stranger could come up to you in the street and scan your face to find out more about you? Google decided to ban facial recognition apps from its ill-fated Google Glass device amid concerns about privacy.

In Russia an app that combined a neural network with facial recognition software scanned social media profiles to link names and photos. This was then used to identify women who had appeared in pornographic movies

But Mr Tayeb says privacy is "baked into" the Blippar app.

"It's a totally opt-in service, the user has full control over what's shown and they're able to deactivate it at any time," he explains.

image copyright Blippar image caption Blippar is currently best known as an augmented reality app that tells users more about everyday objects and brands it is shown

Anyone who does not want their face stored on Blippar's servers, including those 70,000 public figures, can ask to have it removed.

But what happens if a mischievous friend decides to take a photo of you and put it into the database?

Mr Tayeb says the process of creating a face profile involves you taking moving pictures of your own face and claims the system is sophisticated enough to recognise if someone is trying to register someone else.

Blippar believes it is creating a new form of communication involving the most expressive single feature we possess - our faces.

"It's a social tool, something people can have fun with," says Mr Tayeb.

image copyright Blippar image caption Blippar will have to overcome privacy concerns

I'm not entirely clear why people will find facial recognition compelling - though as I get older and more forgetful I can imagine that contact lenses that could tell me exactly who I was talking to would be useful.