Color image enhancement using retinex with robust envelope

In this paper, we propose a color image enhancement method that uses retinex with a robust envelope to improve the visual appearance of an image. The word ¿retinex¿ is hybird ¿retina¿ and ¿cortex¿, suggesting that human visual perception is involved in this color image enhancement. To avoid the gray-world violation, a color-shifting problem, an input RGB color image is transformed into an HVS color image, but only the V component is enhanced. Furthermore, to prevent hallow artifacts, we construct a robust envelope with a gradient-dependent weighting to limit disturbances around intensity gaps such as edges and corners. Our experiment results show that the proposed method yields a better (almost hallow-free) performance than traditional image enhancement methods.