An image processing apparatus includes an imaging unit, a determination unit, and a discrimination unit. The imaging unit images a target object using signals in a predetermined wavelength band in which a spectral transmittance of a specific substance of a plurality of substances on a surface of the target object is different from a spectral transmittance of the other substances of the plurality of substances. The determination unit determines a distribution state of the specific substance on the surface of the target object based on an image captured by the imaging unit. The discrimination unit discriminates a class to which the target object belongs based on the distribution state of the specific substance.