Chapter 11 – Representation

Publisher Summary Segmentation decomposes a picture into subsets or regions. The geometrical properties of these subsets—connectedness, size, shape—are often important in picture description. There are many methods of measuring such properties; the preferred method usually depends on how the subsets are represented. This chapter discusses various representation schemes and their application to geometric property measurement. Each row of a picture consists of a sequence of maximal runs of points such that the points in each run all have the same value. Thus, the row is completely determined by specifying the lengths and values of these runs. The run length coding is sometimes used for picture compression. The set of centers and radii (and values) of the maximal blocks is called the medial axis (or symmetric axis) transformation. It also explains that the maximal connected regions of constant value are analogous to runs; however, they are not good primitive elements for representation purposes as they themselves cannot be specified compactly; a block, on the other hand, is defined by specifying its center and radius.