In this work we describe one experiment investigating the combination of a photometric stereo and a multispectral technique to recover spectral information with an RGB digital camera. A 4-source based-photometric device is used to recover the scene normals and the albedo at each image pixel. We use a multispectral technique based on a linear pseudoinverse method, which directly relates spectral reflectances and RGB camera values. The suggested method uses the recovered albedo for each channel as RGB components to recover the spectral reflectance pixel by pixel. It is possible then to avoid finding different reflectances in different points of the surface due to shadows, as the albedo recovered by photometric stereo techniques is not affected by shadows. We expect that analyzing the difficulties and problems encountered will be useful in applications such us color image reproduction, three-dimensional surface analysis and spectral characterization of materials and micro-facets.
Clara Plata, Juan L. Nieves, Javier Romero, "Combining spectral and photometric stereo techniques for reflectance estimation using an RGB digital camera" in Proc. IS&T CGIV 2008/MCS'08 4th European Conf. on Colour in Graphics, Imaging, and Vision 10th Int'l Symp. on Multispectral Colour Science, 2008, pp 516 - 518, https://doi.org/10.2352/CGIV.2008.4.1.art00111