SHAPE PROCESSING AND ANALYSIS USING THE CALYPTER

After presenting some elementary criteria that should be respected by any automatic shape analysis technique, this paper focuses on the impo rtance of the binary image encoding method. Most image analysers simpl y use a raster image to represent a binary object. If, occasionally, a vectorial description is available, it is merely chosen for its perfo rmances in data compression. Data compression and shape analysis have different goals and usual methods cannot satisfy both. The calypter is a new descriptor vectorizing the shape as a set of maximal inscribed discs. It is the most efficient means of accomplishing Euclidean mathe matical morphology transformations and allows for further developments in binary shape processing. A simple adaptive contour filtering techn ique is presented. The calypter offers local and global perception of shape characteristics. It permits complete automation of the morphomet ric roundness charts used in many laboratories and also generates new shape parameters. A case study of three sand populations is presented to show the pertinence of a new 'equivalent roundness' parameter.