1. A color image processing method comprising: (a) restoring a surface reflectance of a region corresponding to an object which is a subset of the input image from color information of the object and from restored information on spectral power distribution of an illumination under which the input image was photographed; and (b) correcting the surface reflectance of the region so that the surface reflectance of the region approaches that of a pre-specified reference surface reflectance of the object in order to perform color correction to the region, but not the entire input image, and to generate a corrected output image as a function thereof, the correcting comprising: (i) determining matrix elements for a correction matrix that converts a set of characteristic parameters representing the surface reflectance in the region into a set of characteristic parameters representing the pre-specified reference surface reflectance of the region by solving simultaneous equations including the correction matrix for at least three colors; (ii) correcting the surface reflectance of the region of the object using the correction matrix composed of the determined matrix elements; and (c) outputting the corrected output image to an image device.