Multispectral Photometric Stereo Using Intrinsic Image Decomposition

Abstract

One of the main problems faced by the photometric stereo method is that several measurements are required, as this method needs illumination from light sources from different directions. A solution to this problem is the color photometric stereo method, which conducts one-shot measurements by simultaneously illuminating lights of different wavelengths. However, the classic color photometric stereo method only allows measurements of white objects, while a surface-normal estimation of a multicolored object using this method is theoretically impossible. Therefore, it is necessary to convert a multi-colored object to a single-colored object before applying the photometric stereo. In this study, we employ the intrinsic image decomposition for conversion. Intrinsic image decomposition can produce the intrinsic image which is not affected by the reflectance. Since the intrinsic image is the image with white object, we can obtain the surface normal by applying the conventional photometric stereo algorithm to the intrinsic image. To demonstrate the effectiveness of this study, a measurement device that can realize the multispectral photometric stereo method with seven colors is employed instead of the classic color photometric stereo method with three colors.