D. Chithra Prasad

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We show that the region lit by a point light source inside a simple n-gon after at most k reeections oo the boundary has combinatorial complexity O(n 2k), for any k 1. A lower bound of ((n=k ? (1)) 2k) is also established which matches the upper bound for any xed k. A simple near-optimal algorithm for computing the illuminated region is presented, which(More)
We extend the concept of the polygon visible from a source point S in a simple polygon by considering visibility with two types of reflection, specular and dzffuse. In specular reflection a light ray reflects from an edge of the polygon according to Snell's law: the angle of incidence equals the angle of reflection. In diffuse reflection a light ray(More)
In this paper,we focus K-mean clustering based fragile watermarking scheme for image authentication and tamper detection.Tamper detection and localization accuracy are two important aspects of the authentication watermarking scheme. Clustering values of the watermarked image used as the secret key in our scheme. Itcan detect any modification is made to(More)
In recent years, a series of algorithms have been proposed to detect community from social networks. Most of the algorithms are based on traditional spectral clustering algorithms such as k-means. One of the major limitations of such algorithms is that entire eigenvalues of the similarity matrix of the network need to be calculated in advance. In the case(More)
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