Samsung Galaxy S III User Manual page 371

Using Face Unlock
This feature used facial recognition to unlock your phone. This
feature is less secure than PIN, Pattern, and Password locks and can
be bypassed by someone else who looks similar to you.
1. From the main Settings page, tap Lock screen.
2. Tap Screen lock
3. Read the on-screen notification and tap Set it up.
4. Follow the on-screen instructions.
Using Face and Voice Unlock
This feature used facial recognition to unlock your phone. This
feature is less secure than PIN, Pattern, and Password locks and can
be bypassed by someone else who looks similar to you.
1. From the main Settings page, tap Lock screen.
2. Tap Screen lock
3. Read the on-screen notification and tap Set it up.
4. Follow the on-screen instructions.
5. Once prompted to speak and unlock command, tap
and repeat the phrase four times.
6. Once complete, tap Done.
Face unlock.
Face and voice.
Changing Your Settings 363