Construction of sandwich cover of digital objects

Abstract

An algorithm to construct a minimum vertex cover of a digital object from its inner and outer isothetic covers such that it lies within the annular region bounded by its outer and inner isothetic covers is presented here which has (Formula presented.) time complexity, where n being the number of pixels on the contour of the digital object and g is the grid size. After constructing inner and outer covers [2,3], a combinatorial technique is used to construct a sandwich cover. Sandwich cover reduces the storage complexity of the given digital object as it contains less number of vertices compared to inner or outer isothetic cover while preserving the shape of the object. Sandwich cover can be used as shape descriptor by generating several metrics on it.