Fast visual search using focused color matching - active search

Abstract

There exist methods of searching for an object whose position and size are not known in an image. To obtain an accurate result by such methods, the focused region of an input image has to be compared many times with its reference image by varying its position and size. This makes fast searching difficult. This paper describes a method of fast active search for an object and its position in an image by using the color histogram, which is stable to variations of shape of the object. When the input image of an object is compared with its reference image, the upper limit of the similarity in the image region is calculated from the input image in a certain position using the algebraic characteristics of the color histogram. If the upper limit is smaller than the search value, no search in this region is necessary, so that the number of matching operations can be greatly reduced. This method involves no approximations and has a computation speed about 10 to 1000 times faster than conventional exhaustive search methods. Applications of the proposed method, such as tracking, retrieval, and counting, are also describe.