Abstract: A portable data processing apparatus is provided. It has at least one data processing function which depends on detected motion of the apparatus. The apparatus comprises a video camera operable to capture successive images of a part of the real environment around the apparatus; a video motion detector operable to detect motion of the apparatus by analysis of image motion between pairs of captured images; a hardware motion detector operable to detect motion of the apparatus, whereby the data processing function depends on motion detected by the hardware motion detector; and a controller operable to adjust the operation of the hardware motion detector if the motion detected by the video motion detector and the motion detected by the hardware motion detector differ by at least a threshold difference.

Abstract: A portable data processing apparatus is provided. It has at least one data processing function which depends on detected motion of the apparatus. The apparatus comprises a video camera operable to capture successive images of a part of the real environment around the apparatus; a video motion detector operable to detect motion of the apparatus by analysis of image motion between pairs of captured images; a hardware motion detector operable to detect motion of the apparatus, whereby the data processing function depends on motion detected by the hardware motion detector; and a controller operable to adjust the operation of the hardware motion detector if the motion detected by the video motion detector and the motion detected by the hardware motion detector differ by at least a threshold difference.

Abstract: A portable electronic device comprises a display on a first, front side of the device, a touch sensitive surface on a second, rear side of the device substantially opposite the first side having a similar shape and orientation to the display, and a touch input mapping means arranged to map a position of a detected touch on the touch sensitive surface to a position on the display and, a tapping detection means. The tapping detection means is arranged in operation to detect a tap as when there has been a loss and reacquisition of touch from a user on the touch sensitive surface. And the tapping detection means is arranged in operation to detect the position of the detected tap on the touch sensitive surface as being the position at which touch was lost.