Apple Explains More on How Face ID Works on iPhone X


Apple this morning has shared a new support document detailing more about Face ID in iPhone X, titled “About Face ID advanced technology”.

Apple says Face ID works best when your iPhone X “is arm’s length or less from your face (25-50 cm away from your face).” When your iPhone X is “intelligently activated” by tapping the screen, raising to wake or when a notification arrives, the TrueDepth camera will capture your face depth data and an infrared image, to then match it against a “stored mathematical representation to authenticate.”

Screenshot 2017 09 27 10 53 07

There are security safeguards in place for Face ID. Apple reiterates the odds of a random person looking at your iPhone X and authenticating is 1 in 1,000,000 versus 1 in 50,000 for Touch ID. Face ID also limits to five failed attempts before a passcode is required to unlock your iPhone.

But here’s where statistical probability changes—when it comes to twins and children under the age of 13:

The statistical probability is different for twins and siblings that look like you and among children under the age of 13, because their distinct facial features may not have fully developed. If you’re concerned about this, we recommend using a passcode to authenticate.

Also, a passcode will be required when Face ID hasn’t unlocked your iPhone X in the last 4 hours. If you lose your iPhone X, Find My iPhone Lost Mode can prevent Face ID from being used.

Again, Face ID data remains stored locally on your iPhone X within the Secure Enclave, with no data ever leaving your device or stored in the cloud.

As for the TrueDepth camera system, Apple says it “is safe to use under normal usage conditions,” and “will not cause any harm to eyes or skin, due to its low output.” If iPhone X detects tampering to the infrared emitters during repair or disassembly, the TrueDepth camera may be disabled “for safety reasons.”

Components for Face ID are the rumoured cause for iPhone X production delays, which many hope will ease before the device’s October 27th pre-order date.

[via The Verge]


  • Joe

    Why do they have to specifically mention that the camera won’t cause harm to the eyes or skin? Are there circumstances where a TrueDepth camera might harm your eyes or skin?
    That sounds strangely ominous…

  • Theo

    Hey Gary, curious as to where that TD Visa image is from. Looks like TD will have no issues with Face ID, maybe even the Apple cash card too?

  • Olley

    is this the same tech as xbox kinect?

  • Matt

    I don’t think it’s the camera but the thousands of dots they are shining at your face and into your eyes. Some people would be concerned that it could damage their vision or harm their skin like UV rays/lasers would, so they are just letting people know the light is harmless.

  • Albin

    Maybe so for one model smartphone – over the longer term it’s hard to believe Apple (and other OEMs) won’t offer the “convenience” of multi-device face recognition data stored in the cloud instead of repeated activations. Interesting about the four hour time limit and potential concern for infrared eye damage.

  • jabohn

    As I was zipping around town yesterday, repeatedly pulling my iPhone from my pocket, eventually I realized another reason why I would never want to lose TouchID for FaceID: I would be constantly having to lift my phone up to my face. The way I use it now I need to be inconspicuous, so I don’t even have to look at my iPhone – I pull it out of my pocket with my finger on the home button and it’s unlocked and ready to go. Apple had better keep a TouchID model around or I’m out.

  • Apple’s website. If you have an iPhone X, any authentication requests for Touch ID will just be replaced by Face ID.

  • Joe

    Okay, fair enough then. Thanks for the reply, Matt!

    I’m still pretty skeptical about Face ID, but I guess time will tell.

  • Our eyes are exposed to infrared light all the time. I’d guess it’s just as common as visible light. You’d need a fairly bright infrared light that’s on for a significant period of time for it to cause eye damage. It’s completely unnecessary (and therefore extremely unlikely) that FaceID would operate that way.

  • sukisszoze

    I wonder if they incorporate both Face and Touch ID in future version. The Touch ID will probably be anywhere on the screen, or one of the side button?

  • Agreed Matt. I think people freak out when they hear about IR light shining on them, as they think it’s some dangerous thing that they’re not normally exposed to. IR light is everywhere, in fact I would guess it’s just as common as visible light. I’m pretty sure there’s nothing to worry about.

  • Aleks Oniszczak

    Then why would they say, “the TrueDepth camera may be disabled ‘for safety reasons.'”

    Also, “Apple says it “is safe to use under _normal_ usage conditions,” which implies that it’s NOT safe under abnormal conditions – such as if you dropped the phone and had a safety filter break

  • Aleks Oniszczak

    [I wrote this above, but will repeat it here]

    Then why would they say, “the TrueDepth camera may be disabled ‘for safety reasons.'”

    Also, “Apple says it “is safe to use under _normal_ usage conditions,” which implies that it’s NOT safe under abnormal conditions – such as if you dropped the phone and had a safety filter break.

  • Hmm… that’s a very good point. I’m not sure, to be honest, perhaps I’m wrong about how powerful the IR light would need to be. I’m wondering if they mean it could potentially be harmful if you were using the TrueDepth camera more than they anticipate (like using animojis 12 hours a day)? After all, safety limits for light/radiation are all tied to the length of time exposed (for example, we all accidentally glance at the sun for a half-second every now and then, but it can do a lot of damage if you stare at it).