RETRIEVAL DEVICE AND PROGRAM FOR RETRIEVING HIGH DIMENSIONAL FEATURE VECTOR WITH HIGH ACCURACY

PROBLEM TO BE SOLVED: To provide a retrieval device etc. that mitigates the unfairness in determination of similarity between IDs taking into account the density of high dimensional feature vectors for each quantized ID when retrieving such feature vectors.SOLUTION: A retrieval device includes: reference information storage means that stores a plurality of combinations of content IDs and feature vectors for each reference hash ID; hashing means that derives a hash ID for each feature vector; distance calculation means that calculates the distance between each reference feature vector corresponding to a query hash ID and a query feature vector; distance sort means that sorts reference content IDs in the ascending order of shorter distances; reference content ID extracting means that extracts only the reference content IDs included in the higher threshold value percentages (%); and similarity retrieving means that retrieves the most similar reference content among the plurality of reference contents corresponding to the reference content IDs.