1. A method comprising: receiving, by a computing device from a user, a first indication that the user wishes to authenticate himself or herself with the computing device via face verification; in response to the first indication, capturing, by the computing device using a camera, a first series of images of the user's face; authenticating, by the computing device, the user by evaluating each of the first series of images against a face template for the user, wherein the user is authenticated based on an N-th image in the first series; selecting, by the computing device, one or more images from the first series prior to the N-th image; adding, by the computing device, the one or more images to the face template for the user; at a later point in time, receiving, by the computing device from the user, a second indication that the user wishes to authenticate himself or herself with the computing device via face verification; in response to the second indication, capturing, by the computing device using the camera, a second series of images of the user's face; and authenticating, by the computing device, the user by evaluating each of the second series of images against the face template for the user, wherein the user is authenticated based on an M-th image in the second series, and wherein M is less than N.