Here’s Why Sunglasses Can Interfere with Facial ID

The facial ID technologies now starting to show up on our smartphones make it possible to unlock the device without having to swipe or enter a numerical code. All you do is pick up your phone and look at it. Facial recognition software determines whether or not you are the person on file and, if you are, the phone is unlocked.

All of this is well and good, but sometimes the technology doesn’t work. Say you are wearing a pair of sunglasses and trying to unlock your phone at the same time. The software may not recognize your face, subsequently leaving you locked out until you remove your sunglasses. What gives?

Smartphones and sunglasses have historically not played well together. Even before there was facial ID software, people discovered that they could not read their phone screens while wearing sunglasses. It turns out that polarization was the problem. Polarized lenses block light waves traveling in a certain direction, making it impossible to read a cell phone screen that is polarized in the same direction. However, the solution is simple: rotate your screen 90° and you are in business.

Facial Recognition Software

The conflict between polarized sunglasses and smartphone screens is old news. Let us move on to the new problem of facial recognition. We can use the latest iteration of the iPhone to illustrate the problem. The iPhone relies on something known as a TrueDepth camera to make it all work.

The camera and software are both designed to recognize faces giving attention to the screen. In other words, they are expecting users to be looking at their screens with eyes fully visible. The software can then map specific points on the eyes with those stored in the software to identify the person trying to unlock the phone.

It should be obvious that mapping a person’s eyes is not possible if sunglasses are in the way. So if you are trying to use Face ID on the iPhone and you are wearing sunglasses, your phone’s camera and software will assume you’re not looking at the screen.

Working on a Solution

Technology makers are working on a solution but, for now, the only workaround is to either remove your sunglasses or change the settings on your phone. Switching to non-polarized lenses isn’t going to work, according to Olympic Eyewear out of Salt Lake City, Utah.

The designer of more than two dozen brands of fashion sunglasses says that polarization is achieved through a separate filter built in to the lenses. It has nothing to do with blocking out visible light, which is the property that prevents a phone camera from identifying human eyes.

If you have an iPhone and you are using Face ID, you can get around the sunglasses issue by going into the phone’s settings and turning off the feature that requires attention for Face ID to work. Turning off attention still allows the software to work by forcing it to rely on other facial points for recognition.

A Less Secure Phone

Note that changing settings to no longer require attention does make your phone less secure. Without requiring recognition of the eyes, someone could unlock your phone while you’re sleeping simply by pointing it at your face. In theory, someone with similar facial features might also be able unlock it while wearing a pair of sunglasses.

Biometric security features like facial recognition will eventually be the norm. But first, manufacturers have to work out all the bugs. That includes the one that could make it impossible for your phone to recognize your face while you’re wearing shades.

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About the Author: Curry Shell