Method of compiling image database, image database compilation program, image retrieval method

Abstract

A method for creating an image database comprising an extraction step of extracting reference feature vectors from a reference image which should be compared with a retrieval query image for object recognition, the reference feature vectors corresponding to local features at different positions of the reference image and representing the position and characteristics of each of the local features as a vector position, vector length, and a vector direction, a clustering step of creating a plurality of clusters consisting of different reference feature vectors in such a manner that each reference vector belongs to any of the plurality of clusters, a selection step of selecting the representative vector of the clusters from among the reference feature vectors of each of the clusters, and a step of associating the representative vector with the reference image and registering the representative vector associated therewith in the image database for the object recognition, wherein, in the clustering step, each of the clusters is created in such a manner that reference feature vectors at a near vector position belong to the same cluster, and in the selection step, reference feature vectors with long vector length are given priority to select the representative vector, and wherein the retrieval query image and the reference image are compared with each other by generating at least one query feature vector from the retrieval query image, and applying local search between the query feature vector and the representative vector, each of the steps being executed by computers.