Finding largest rectangle inside a digital object

Abstract

We present a combinatorial algorithm which runs in O(n log n) time to find largest rectangle (LR) inside a given digital object without holes, n being the number of pixels on the contour of digital object. The object is imposed on background isothetic grid and inner isothetic cover is obtained for a particular grid size, g, which tightly inscribes the digital object. Certain combinatorial rules are applied on the isothetic cover to obtain the largest rectangle. The largest rectangle is useful for shape analysis of digital objects by varying grid size, by rotating the object, etc. Experimental results on different digital objects are also presented.