US Patent 8984622 User authentication through video analysis

A user of a computing device can be authenticated using image information captured by at least one camera of the computing device. In addition to analyzing the image information using a facial recognition algorithm, for example, variations in color of a portion of the captured image information corresponding to a user's face can be monitored over a period of time. The variations can be analyzed to determine whether the captured image information likely corresponds to an actual human user instead of a representation (e.g., photo) of a human user, such as where the chroma variations in at least a red channel occur with an oscillation frequency and amplitude consistent with changes due to a pulse or heartbeat.