1. A method comprising particular steps of: determining a first intensity value for a first region of an image; determining a second intensity value for a second region of the image; generating a first feature value for a first feature at least in part by dividing the first intensity value by the second intensity value; determining whether the first feature value falls within a specified range that is associated with the first feature; and in response to determining that the first feature value falls within the specified range that is associated with the first feature, storing data that indicates that the image contains a face; wherein the steps are performed by an automated device.