Method, apparatus and program for restoring and correcting surface reflectance with color image processing

摘要

Spectral power distribution of an illumination is restored using color information in a region of the specific object in an input image and a pre-specified representative surface reflectance of the specific object. The surface reflectance in the region of the specific object is restored from the color information and the spectral power distribution of the illumination. The surface reflectance is corrected using three or more pre-specified reference surface reflectances of the specific object. The color in the region of the specific object is calculated from the spectral power distribution of the illumination and the corrected surface reflectance.

主权项

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.