Face ID

Face ID is a facial recognition system designed and developed by Apple Inc. for the iPhone (X, XS, XS Max, XR, 11, 11 Pro, 11 Pro Max) and iPad Pro (third and fourth generation). A successor to Touch ID, the system allows biometric authentication for unlocking a device, making payments, and accessing sensitive data, as well as providing detailed facial expression tracking for Animoji and other features. Initially released in November 2017 with the iPhone X, it has since been updated and introduced to most new iPhone models, and all iPad Pro models.

Face ID is based on a facial recognition sensor that consists of two parts: a dot projector module that projects more than 30,000 infrared dots onto the user's face, and an infrared camera module that reads the pattern. The pattern is encrypted and sent to a local "Secure Enclave" in the device's CPU to confirm a match with the registered face. The stored facial data is a mathematical representation of key details of the face, and it is inaccessible to Apple or other parties. To avoid involuntary authentication, the system requires the user to open their eyes and look at the device to attempt a match, although this can be disabled through an accessibility setting. Face ID is temporarily disabled and the user's passcode is required after 5 unsuccessful scans, 48 hours of inactivity, restarting the device, or if two of the device's side buttons are held briefly.

Apple claimed the probability of someone else unlocking a phone with Face ID is 1 in 1,000,000 as opposed to Touch ID at 1 in 50,000. During initial setup, the user's face is scanned twice from a number of angles to create a complete reference map. As the system is used, it learns about typical variations in a user's appearance, and will adjust its registered face data to match aging, facial hair growth, and other changes using the Neural Engine. The system will recognize a face wearing hats, scarves, glasses, most sunglasses, facial hair or makeup. It also works in the dark by invisibly illuminating the whole face with a dedicated infrared flash module.

Authentication with Face ID is used to enable a number of iOS features, including unlocking the phone automatically on wake, making payments with Apple Pay, and viewing saved passwords. Apps by Apple or third party developers can protect sensitive data with a system framework; the device will verify the user's identity and return success or failure without sharing face data with the app. Additionally, Face ID can be used without authentication to track over 50 aspects of a user's facial expression and positioning, which can be used to create live effects such as Animoji or camera filters.

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