Rumours about new iPhones normally centre on the screen, processing chips or whether there will be a headphone jack. But a new report from 9 to 5 Mac highlights something that could be a little controversial for Apple's next smartphone: a camera that can map your face.

Apple may be considering a camera designed for authentication and augmented reality for its next high-end iPhone, according to a research note from Apple analyst Ming Chi Kuo of KGI Securities. With a better sense of depth, this type of camera can tell how far away something is from the lens. It could even generate something like a 3D selfie, 9 to 5 Mac reported.

Apple declined to comment on the rumours.

Adding such a camera seems to be a natural next step for Apple. It already organises iPhone photos based on the subjects it recognises in the images. And its competitors, such as Microsoft and Samsung, have used facial recognition for years to unlock phones.

You may have heard in passing, however, that facial recognition technology has had some problems. Companies including Hewlett-Packard and Nikon have faced criticism when their cameras had trouble recognising non-white faces and features. Some experts say that problem could arise when the algorithms aren't exposed to a variety of faces while in development.

Security experts have also raised questions about facial recognition as a form of authentication because it doesn't always work that well. Wearing a baseball cap or even makeup can keep some sensors from recognising your face, experts said. People have also found ways to trick some types of facial recognition scans, such as holding a video of a phone owner's face up to less sophisticated recognition sensors.

But experts say that Apple's reported plan to use a depth-sensing camera for the feature addresses those issues.

"You can get much more accurate readings," said Chester Wisniewski of the security firm Sophos. "There are things that can mess with visual sensors. This sees through makeup, to tissue." Plus, he said, this type of camera isn't easily fooled; even a 3D-printed model of a face shouldn't trick it.

According to Consumer Reports, these sorts of cameras have also been shown to have fewer problems recognising dark skin tones. Microsoft's version of depth-sensing cameras — made by Intel — can tell identical twins apart, according to tests.

One concern

But there's one concern about facial recognition technology that may not be resolved by a depth-sensing camera: privacy. The technology would likely give these companies a pretty comprehensive map of your face, which may give some people the creeps and raise fears about how the identification data could be used. Of course, we won't know how Apple will handle this data until an official announcement. And we won't know until then whether the feature can be disabled by the user.

Apple has made several public commitments to protecting user privacy and information. When it introduced the photo features last June, the company took great pains to explain that it stores information only on a person's device, just as it does with your fingerprints.

The company also has said that it practices what's called "differential privacy," a type of data collection that aims to prevent the ability to identify someone by their phone data.

While some privacy experts lauded Apple for taking those steps, however, they also called on the company to give customers more information about how the data is collected, used and shared.

Researchers from the Electronic Frontier Foundation, a nonprofit devoted to digital rights, said last year that Apple's approach to privacy should be applauded but that Apple should be more open about its methods and research to enable "technologists, researchers, and companies to learn from it" and advance privacy standards in the industry overall.

Apple has focused heavily on developing facial recognition technology in recent years. In addition to acquiring PrimeSense, the company that developed the original Kinect, Apple has bought a handful of facial recognition companies — including one firm that will animate your facial expressions in real time. Just last week, Israeli media reported that Apple picked up a start-up called RealFace, which uses facial recognition for security purposes.