IMAGE PROCESSING APPARATUS, IMAGE PROCESSING METHOD AND PROGRAM

An image processing apparatus reduces two input images to be compared by the predetermined number of times to generate two image groups, extracts a plurality of feature points and a local feature amount of each feature point from these image groups, and determines a combination of feature points in which local feature amounts are similar to each other, between the image groups. Then, the image processing apparatus determines a relation of a reasonable combination, assigns high weights to the reasonable combination, and calculates a similarity degree between the two input images.