Iterated Function Systems and Two-Dimensional Shape Representation

A fundamental requirement of any vision system designed to perform recognition tasks is a library of representations of objects it is likely to encounter. The classic approach to constructing such representations is to decompose the shape into simple primitive elements. However, for complex shapes it is usually necessary to use a large number of such primitives to achieve an accurate decomposition. The alternative is to define more complex, context-specific primitives, which would be of practical use for only a small set of shapes. The advantage of using an Iterated Function System (IFS) instead is that it enables us to construct a recursive definition of shape. This is achieved by using contractive affine transformations of the original shape as the primitives in its decomposition, and thus removing the need for shape primitives to be defined prior to encoding.