Image Retrieval Using the Centroid Based Shape Descriptor

Abstract

Shape analysis is used in many application field including security applications, medical field ,agricultural field,cyber crime and many more. A shape descriptor is the simplified representation of the images. These shape descriptor contain the information of that image which will help to store the image information and make easy comparison between the images or easy for matching the different shapes .The proposed method is centroid based shape descriptor. The type of shape descriptor used here is boundary based shape descriptor. Distance from center of bounding box encompassing the edge image to farthest point on the edge is calculated. A circle is drawn using the distance mentioned above as radius (the farthest distance between centroid and edge pixel). A line using Bresenham algorithm drawn between two opposite pixels on circle forms the bases of computation. Distances between all the edge pixels falling on the above mention line are computing , these distance matrix is nothing but the features extraction for image. The descriptor is divided into segments so as to avoid global distribution. A rotational matching scheme ensures invariance to rotation. As the computation of feature set is compact, implementation of this method results in quick retrieval of images invariant to scaling, translation and rotation.