Use of Quadtrees for Edge Enhancement

A quadtree approximation of a 2 to the nth power by 2 to the nth power gray level image tends to enhance edges that are strong in the original image and suppress those that are weak. An edge detector applied to such an approximation produces edges that are in general stronger than those obtainable from the original, though slightly displaced. Methods of combining the edge maps obtained from the original image and its quadtree approximation are examined. It is shown that the choice of a suitable combination rule results in an edge map which is superior to that obtainable by conventional means.