Portable data processing appartatus

A method of operation of a portable data processing apparatus having at least one data processing function which depends on detected motion of the apparatus, the method comprising:

• capturing successive images of a part of a real environment around said apparatus;
• detecting motion of said apparatus corresponding to inter-image motion in at least a majority of an image, as detected between pairs of captured video images;
• detecting motion of said apparatus with a hardware motion detector, whereby said data processing function depends on motion detected by said hardware motion detector;
• and
• adjusting the operation of the hardware motion detector if the motion detected by image analysis and the motion detected by said hardware motion detector differ by at least a threshold difference.

A tangible computer-readable storage medium on which computer readable instructions of computer software are stored, the instructions, when executed by a computer, cause the computer to perform a method of operation of a portable data processing apparatus having at least one data processing function which depends on detected motion of the apparatus, the method comprising:

• capturing successive images of a part of a real environment around said apparatus;
• detecting motion of said apparatus corresponding to inter-image motion in at least a majority of an image, as detected between pairs of captured video images;
• detecting motion of said apparatus with a hardware motion detector, whereby said data processing function depends on motion detected by said hardware motion detector;
• and
• adjusting the operation of the hardware motion detector if the motion detected by image analysis and the motion detected by said hardware motion detector differ by at least a threshold difference.