Intrinsic illumination subspace for lighting insensitive face recognition.

We introduce the intrinsic illumination subspace and its application for lighting insensitive face recognition in this paper. The intrinsic illumination subspace is constructed from illumination images of intrinsic images, which is a midlevel description of appearance images and can be useful for many visual inferences. This subspace forms a convex polyhedral cone and can be efficiently represented by a low-dimensional linear subspace, which enables an analytic generation of illumination images under varying lighting conditions. When only objects of the same class, such as faces, are concerned, a class-based generic intrinsic illumination subspace can be constructed in advance and used for novel objects of the same class. Based on this class-based generic subspace, we propose a lighting normalization method for lighting insensitive face recognition, where only a single input image is required. The generic subspace is used as a bootstrap subspace for illumination images of novel objects. Face recognition experiments are performed to demonstrate the effectiveness of the proposed lighting normalization method and verify empirically that the class-based generic subspace is applicable to novel objects. Our method is simple and fast, which makes it useful for real-time applications, embedded systems, or mobile devices with limited resources.