IMAGE PROCESSING APPARATUS

An image processing apparatus, including an image taking device which takes an image of an object, an image-data memory in which image data representing the taken image of the object is stored, a negative-search-line producing device which produces one or more negative search lines which are expected not to intersect an edge of the image of the object represented by the image data, an optical characteristic of the image significantly changing at the edge, and a judging device which judges whether one or more negative search lines intersect the edge of the image of the object.