A dedicated base vector based on a known spectral characteristic of a subject as an identification target having the known spectral characteristic and a spectral characteristic of an imaging system, which includes a spectral characteristic concerning a color imaging system used for image acquisition of subjects including the subject as the identification target and a spectral characteristic concerning illumination light used when image acquisition of the subjects by the color imaging system, are acquired. A weighting factor concerning the dedicated base vector is calculated based on an image signal obtained by image acquisition of the subject by the color imaging system, the dedicated has vector, and the spectral characteristic of the imaging system. An identification result of the subject which is the identification target having the known spectral characteristic is calculated based on the weighting factor concerning the dedicated base vector to output as an output signal.
