In this paper we introduce a new simple strategy into edge-searching of a graph, which is useful to the various subgraph listing problems. Applying the strategy, we obtain the following four algorithms. The first one lists all the triangles in a graph G in O(a(G)m) time, where m is the number of edges of G and a(G) the arboricity of G. The second finds all the quadrangles in O(a(G)m) time. Since a(G) is at most three for a planar graph G, both run in linear time for a planar graph. The third lists all the complete subgraphs K of order in O(la(G)t-2m) time. The fourth lists all the cliques in O(a(G)m) time per clique. All the algorithms require linear space. We also establish an upper bound on a(G) for a graph G: a(G) <-[(2m+ n)1/2/2], where n is the number of vertices in G.
We propose a fast, high quality tone mapping technique to display high contrast images on devices with limited dynamicrange of luminance values. The method is based on logarithmic compression of luminance values, imitatingthe human response to light. A bias power function is introduced to adaptively vary logarithmic bases, resultingin good preservation of details and contrast. To improve contrast in dark areas, changes to the gamma correctionprocedure are proposed. Our adaptive logarithmic mapping technique is capable of producing perceptually tunedimages with high dynamic content and works at interactive speed. We demonstrate a successful application of ourtone mapping technique with a high dynamic range video player enabling to adjust optimal viewing conditions forany kind of display while taking into account user preference concerning brightness, contrast compression, anddetail reproduction.
Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Image Processing and Computer Vision]: Image Representation
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