Video data comprising a plurality of sets of frame data is captured by mobile video data capture device. The video data is processed by a method which comprises: (a) finding a face in each frame of the video, and (b) processing a corresponding set of frame data to: (i) maintain the area of the image occupied by the face substantially constant; and (ii) maintain the apparent direction of light incident upon the face substantially constant; and/or (iii) maintain the apparent color of the face substantially constant.