Apple buys artificial intelligence 'emotion measurement' firm Emotient

Apple has bought a company behind artificial intelligence (AI) technology that can recognise facial expressions.

The tech giant confirmed to the Wall Street Journal that it had bought Emotient, but did not provided details of the deal or elaborate on its plans for the firm.

Emotient, which bills itself as "a leader in emotion measurement", has sold technology to advertisers who use it to work out what viewers make of their ads.

"Wherever there are cameras there can be video analysis of expressions, and an opportunity to learn about the customer’s state of mind as they emotionally respond to marketing, product and service experiences," Emotient says on its website.

Doctors have also called on Emotient to help them interpret signs of pain among patients and one retailer monitored shoppers' facial expressions with its tools, the WSJ said.

Apple is not the only tech firm interested in image recognition. Rivals including Facebook and Alphabet parent Google are investing in AI techniques.

In a video on its website, Facebook describes how it is developing AI that can read the contents of images to the visually impaired. Other software automatically recognises faces for photo tagging.

Emotient was founded in 2012 and is based in San Diego.

In 2014 it raised $6 million to apply its technology to the wearables market, according to a TechCrunch.

It created an app for Google Glass, which Google stopped selling last year.