On finding an orthogonal convex skull of a digital object

A combinatorial algorithm to compute an orthogonal convex skull of a digital object imposed on the background grid is presented in this paper. The proposed algorithm has the time complexity of O(n log n), which improves the earlier method of O(n2) time complexity for finding the convex skull of a simple orthogonal polygon. A set of rules is formulated first and then an orthogonal convex skull is derived by applying these rules while traversing along the boundary of the inner orthogonal polygon that tightly inscribes the given digital object. The algorithm uses only comparison and addition in the integer domain, which makes it amenable to fast real‐world applications. Experimental results on different shapes have also been presented to demonstrate the efficacy and elegance of the proposed technique. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 14–27, 2011.

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