1. A display arrangement comprising: an image display device having two or more sets of images for display; a camera directed towards positions adopted by users viewing said display; a face detector for detecting human faces in images captured by said camera, said face detector being arranged to detect faces in at least two face categories; and a selector, responsive to a frequency of detection of categories of faces by said face detector in respect of one or more different periods, for selecting a set of images to be displayed on said image display device at that period.