Relative gradients for image lighting correction

A fundamental problem in computer vision is to enhance images under various lighting conditions. This paper proposes an approach to lighting correction through reconstructing the image based on relative gradients. Compared with the absolute gradients as exemplified in the originally acquired image, the relative gradients are more stable under the variation of lighting. Extensive experiments have been carried out over images under a wide range of lighting variations. Comparisons with popular lighting correction methods are presented.