A New Active Convex Hull Model for Image Database’s Search Space Partitioning

Abstract

Abstract: This paper presents a new active convex hull model to be used for search space partitioning to decrease the time needed for image retrieval from large image database. The model is based on the geometric heat differential equation and has the following advantages: capable of automatic image segmentation to shells; large capture range; invariant with respect to scaling, rotations and translations; can handle regions without edges. Using the model a tool is developed capable of detecting the convex hull (CH) of each region within the image database and the query image. Employing the illumination theorem the set of database CHs is partitioned to 344 sub-bases. Thus, for each query region a search is performed in this sub-base, whose CH most closely matches the CH of the query region. It provides a factor of hundred reductions in the number of image database regions necessary to be traversed and compared with the query regions. The latter is an important advantage, because matching query shapes against every region conflicts with the goal of high retrieval speed. Key Words: geometric heat differential equation, vector field, segmentation, fast image retrieval