Abstract: A novel forward and backward diffusion based image denoising and enhancement method is proposed.In the proposed method,the direct gradient computation is replaced by a nonlinear structure tensor(NLST) to increase the robustness to noise;The shock filter item along the gradient direction is replaced by a forward or backward diffusion according with the adaptive threshold value of gradient;The corner structure is also enhanced by performing a backward diffusion in corner region.Two experimental results show that the proposed algorithm not only removes noise,but also efficiently enhances image texture details and no artifacts are produced.