Separating Specular, Diffuse, and Subsurface Scattering Reflectances from Photometric Images

While subsurface scattering is common in many real objects, almost all separation algorithms focus on extracting specular and diffuse components from real images. In this paper, we propose an appearance-based approach to separate non-directional subsurface scattering reflectance from photometric images, in addition to the separation of the off-specular and non-Lambertian diffuse components. Our mathematical model sufficiently accounts for the photometric response due to non-directional subsurface scattering, and allows for a practical image acquisition system to capture its contribution. Relighting the scene is possible by employing the separated reflectances. We argue that it is sometimes necessary to separate subsurface scattering component, which is essential to highlight removal, when the object reflectance cannot be modeled by specular and diffuse components alone.