An apparatus includes a processor that extracts a plurality of feature points from a biological image, calculates a feature value of each of the plurality of extracted feature points, normalizes the calculated feature values to values of N levels (N is any natural number) based on a distribution of the feature values, and translates each normalized feature value to binary data by setting a number of bits corresponding to the normalized feature value to one of two digits in accordance with to a given order to make the normalized feature value and the number of bits with the one digit proportional to each other.