In this paper, a new type of diffusion process that simultaneously denoises and sharpens image is considered. A coupled shock-diffusion filter is presented, where, according to image features such as edges, textures, and fine parts, it performs a forward smoothing along the tangent direction to the isophote lines (edges), a backward (inverse) sharpening along the normal directions, or only an isotropic diffusion, respectively. To eliminate the conflict between the backward and the forward force, we split them into a coupled scheme. Experimental results demonstrate that our algorithm can substantially enhance image features on denoising image