New Apple patents explain ‘particle cloud’ pairing method used for Apple Watch

BY Killian Bell

Published 5 May 2015

Apple Watch setup - automatic pairing

If you’ve already got your hands on an Apple Watch, you’ll be familiar with its unique set up process, which simply requires you to point your iPhone’s camera at a pattern on its screen to marry the two together. Now two new Apple patents could explain the magic behind the whole thing.

Published today by the U.S. Patent and Trademark Office, both patents are entitled “Invisible optical label for transmitting information between computing devices,” and they detail a pairing process that looks and sounds a lot like that used with the Apple Watch.

The invention uses data-rich optical labels that cannot be read by end users, but are capable of transferring data from one device to another — much like QR codes. What’s really clever about Apple’s system, however, is how it disguises those labels.

The labels are embedded into images and colored using two alternating frames. In one frame, the label uses two colors, and in the other, another two colors that, when seen together, almost cancel each other out. When alternating at high frequencies of 60 fps to 120 fps and beyond, then, we cannot see them.

“Since the human eye is more sensitive to changes in luminance, or brightness, than chrominance, color changes to the specially encoded optical label will likely go unnoticed,” AppleInsider explains. “For an imaging sensor, however, chrominance changes are easily distinguishable.”

It’s hard to say for certain that this is the pairing employed by Apple Watch, but it’s certainly sounds just like it. When pairing Watch with an iPhone for the first time, users can simply point their iPhone’s camera at an image on the Watch’s display, and the two are almost instantaneously connected.