Here’s a small tutorial for everyone.
You can log in to the PS4™ system with face data added using a PlayStation®Camera. When logging in, the camera recognizes your face. Set a checkmark in [Login Settings] > [Enable Face Recognition].
- To add face data, select [Login Settings] > [Face Data Management].
- When adding face data or logging in to the system by using face data, follow these guidelines.
- Brighten your room.
- Reduce backlighting (the brightness behind you).
- If the light from the windows is too strong, close the curtains and use interior lighting.
- Move about 2 m (6 ft) away from the PlayStation®Camera.
- Arrange your hair so that it does not come in contact with your eyebrows.
- Peel off the protective film from the lenses.
- If the lenses are dirty or have fingerprints on them, clean them with a soft cloth.
- If the camera cannot correctly recognize your face, select [Login Settings] > [Face Data Management] > [Add Face Data], and then add your face data again.
Source: http://manuals.playstation.net/document/en/ps4/settings/facerecognition.html