PROGRAM AND METHOD FOR EXTRACTION OF FEATURE VECTOR SUITABLE FOR IMAGE RETRIEVAL, AND IMAGE RETRIEVAL DEVICE

PROBLEM TO BE SOLVED: To extract a feature vector of a feature point that enables execution of image retrieval with a high degree of retrieval accuracy and with few calculation resources even if images to be compared differ in rotation and scale.SOLUTION: A method includes: a step (S3) of, with respect to m feature point sets, selecting a kst nearest feature point q from an attention feature point pto be an extraction target of a feature vector; a step (S4) of deriving distance r of a straight line p-q; a step (S5) of deriving one or more feature point sets B included in the neighborhood of a predetermined length from a circumference with pset as a center and a distance r set as a radius; and a step (S6) of rotating pand each feature point b of B so as to make an angle constant, and calculating a feature vector f of pusing all of m feature points.