These approximations have two important properties. Algorithms are given for constructing the approximation sequences as well as decoding them to rebuild the original quadtree. This paper presents a thorough explanation of many pointerless quadtree representations for black and white images. The pointerless approach is chosen because pointers cause an inherently high overhead. Terminal nodes are those blocks which require no further subdivision.
Terminal nodes can be either black or white.
In the pointerless representation, each terminal node is represented by use of a locational code corresponding to a sequence of directions that indicate a path from the root. The root node is at level 0. An approximation is obtained by representing the tree only to the required level, which corresponds to the clarity of the resulting image. The concept of a forest is introduced as a method of approximation. A forest is a collection of black parental nodes and black terminal nodes having no black parent.