Apple has filed a new patent application with the U.S. Patent and Trademark Office. And it means that a future Apple Watch might implement a Wrist ID authentication feature to automatically unlock the device whenever you put it on, bypassing the passcode.

Unlocking Your Watch by Putting It On

The patent application, titled "Wearable Electronic Device Having a Light Field Camera," details a new light field camera sensor built into the back crystal of the watch, tasked with shinning a light on the user's wrist to capture a high-resolution image of the region.

In order to make the whole process reliable and as spoof-proof as possible, the captured image would be passed to machine learning for detailed analysis of the vein patterns in the wrist.

A drawing accompanying Apple's patent application for a Wrist ID authentication system for Apple Watch

The invention is credited to Apple engineers Giovanni Gozzini, Dale Setlak, Manohar B. Srikanth, and Mohammad Yeke Yazdandoost. Keep in mind there are no guarantees that this technology will ever be implemented on the Apple Watch. Apple regularly patents various inventions as a defensive strategy, with many of them never used in real products.

Tattoos Could Prove Tricky for Wrist ID

It isn't clear from Apple's filing with the USPTO whether this so-called Wrist ID system would be as reliable as the company's existing Touch ID fingerprint scanner. There's also the question of tattoos, which are known to impact the performance of the Apple Watch sensors.

Related: How to Unlock Your Mac With Apple Watch

According to Apple, "some tattoos can block light from the sensor, making it difficult for the Blood Oxygen app to get a measurement". Because of that, it's safe to assume that Wrist ID may not work well with tattooed wrists. That's because inked areas covering vein-filled sections of the wrist could easily confuse the electrical heart rate sensor.

A drawing accompanying Apple's patent application for a Wrist ID authentication system for Apple Watch

People who tend to take their watch off once a day, usually before going to sleep, may not be big on Wrist ID. However, getting rid of the passcode is always a good thing. Wrist ID even has the potential to advance Apple's Continuity feature (it's an umbrella term for technologies allowing you to seamlessly move between devices).

Unlocking an iPhone With Your Apple Watch

As an example, Apple customers can already configure their Mac so that it automatically unlocks when they're wearing their Apple Watch. With Wrist ID, it might theoretically be possible to have an iPhone or iPad unlock automatically whenever you're wearing your Apple Watch.

One can even imagine a multi-user system for the watchOS operating system where Wrist ID would actually recognize who's wearing the device, unlocking it accordingly.

Taking this all in, Wrist ID sounds like an excellent feature; one that would definitely bolster biometrics on the Apple Watch whilst allowing Apple to get even more creative with the Continuity features. And it's not like one of those crazy patents that you just know will never see the light of day.

For what it's worth, the Cupertino tech giant was recently granted a patent for under-display biometrics in future devices, and another one outlining a Touch ID button for a future Apple Watch, embedded in the Digital Crown or the side button.