Simple and efficient modifications of the original error-diffusion algorithm are proposed to remove the structural artifact and enhance the real structures. The input image is separated into the flatten and detailed areas based on a gradient-based measure. While a randomization is applied to remove the structural artifact in the flatten area, a gradient-based diffusion modulation is applied to enhance the real structures in the detailed area. Furthermore, tone modulations are introduced to achieve sufficient structural-artifact breaking without producing notable noise. These algorithms are simple and maintain the computational efficiency of the original methods. Numerical experiments show that this method is not only outperforming previous simple approaches but also able to achieve comparable visual quality with those obtained by previous sophisticated and computationally expensive approaches.