An image processing apparatus includes an acquiring unit, a specifying unit, a search unit and a difference extracting unit. The invention provides a Ge-doped n-type Group III nitride semiconductor layer with low resistance and excellent flatness, in order to obtain a Group III nitride semiconductor light emitting device exhibiting low forward voltage and excellent light emitting efficiency. An extension portion which is configured to have a pair of feet which are coupled to the posterior surface of the resected femur is rotatably coupled to the base portion.