Robust albedo estimation from face image under unknown illumination

Abstract

Uncontrolled illumination poses severe problems for face recognition in practical application scenarios. Many techniques to deal with this problem rely on illumination modeling and face relighting. In this paper we propose a robust approach to face albedo estimation in the framework of illumination modeling with Spherical Harmonics. This technique requires only a single face image under arbitrary illumination and assumes the face shape is known. The recovered face albedo facilitates face rendering under new illumination conditions which is useful for both illumination invariant face recognition and computer animation. In the proposed approach, the consequences of the violation of the assumption of validity of the spherical harmonics model are mitigated by minimising a cost function involving robust forms of the error in both the spherical harmonics model and the smoothness constraint. The robust estimation provides significantly better results than the traditional Least Squares Estimation in the experiments on a 3D face database.