Abstract: A camera unit that comprises an image sensor and a motion sensor performs an image capture operation in which still images are captured intermittently without triggering by a user. The brightness of illumination during the capture of images is determined. Exposure time is controlled in dependence on both the brightness of illumination and the detected motion.

Abstract: A camera unit that captures still images determines whether the camera unit is outdoors or indoors, and in dependence on that an exposure mask of weights in respect of areas of an image to be an outdoor or indoor exposure mask is selected. The outdoor exposure mask has weights in respect of areas of the image corresponding to a lower region of a scene being imaged and weights in respect of areas of the image corresponding to an upper region of a scene being imaged in a ratio that is greater than the corresponding ratio in the indoor exposure mask. A brightness measure of the overall brightness of captured images is derived from the brightness of areas of the images weighted by the selected exposure mask. The exposure of captured images is controlled in dependence on the brightness measures of previously captured images.