In one embodiment, while a mobile electronic device is in a first operation state, it receives sensor data from one or more sensors of the mobile electronic device. The mobile electronic device in a locked state analyzes the sensor data to estimate whether an unlock operation is imminent, and in response to a positive determination, initializes the camera subsystem so that the camera is ready to capture a face as soon as the user directs the camera lens to his or her face. In particular embodiments, the captured image is utilized by a facial recognition algorithm to determine whether the user is authorized to use the mobile device. In particular embodiments, the captured facial recognition image may be leveraged for use on a social network.