MATCHING APPARATUS, IMAGE SEARCH SYSTEM, AND HISTOGRAM APPROXIMATE RESTORING UNIT, AND MATCHING METHOD, IMAGE SEARCH METHOD, AND HISTOGRAM APPROXIMATE RESTORING METHOD

A matching apparatus and method compares a set of feature points of two objects projected to an N-dimensional space and determines the similarity between the objects and includes mapping the set to a one-dimensional space, creating a set of pairs of a feature point of first object that is the most approximate to a feature point of second object, partly extracting the pairs in small order of the pair distance from the set of the pairs of the feature points and creating a partial set of the pairs of the feature points, calculating a rating-scale of the pair belonging to the partial set of the pair of the feature points, and determining the similarity between the first object and the second object on the basis of an average value of the distance.