The image data in most cases consists of two dimensinal data array, because it is the natural form for image input systems. While, some other data structues are expected to be more effective and convenient. The "image pyramid" and "image quadtree" are such structures. The image pyramid is the multi-layered data arrays with multi-resolutions. The image quadtree is an expression of black-and-white pictes using the four-branching tree. Some of the fundamental image processing algorithms have been developed on such data structures.