Shape Description by Region Analysis

Abstract

One approach to shape analysis is to perform certain measurements directly on a region or object. Quantities like width, elongation, ratio of perimeter square over area, etc., have all been used as shape descriptors. In general, these convey only gross information and they are inadequate for subtler distinctions, like separating a printed “f” from a “t”. An alternative approach is to check the occurrence of certain simple configurations on the input picture. The two characters “f” and “t” could be distinguished from others by the occurrence of a short arc and from each other by the location and orientation of that arc. This “mask matching” may be generalized to the evaluation of weighted integrals over the whole picture. A rigorous way of doing this is offered by the method of moments which is described in the next section.