1. A computer implemented method, comprising: under control of one or more computer systems configured with executable instructions, capturing a first image using a camera, the first image including first image data corresponding to at least one portion of a human face taken at a first angle relative to the camera; analyzing the first image data to identify the at least one portion of the human face; capturing a second image using the camera, the second image including second image data corresponding to the at least one portion of the human face taken at a second angle relative to the camera; analyzing the first image data and the second image data to detect changes in one or more characteristics corresponding to the at least one portion of the human face; determining, based at least in part on the changes in the one or more characteristics, that an artificial representation of the at least one portion of the human face is presented in the first image and the second image; and preventing access to at least one function of a computing device.