Image smoothing and sharpening based on nonlinear diffusion equation

For the sake of the smoothing image and sharpening the edge features of the image, a nonlinear diffusion model for image smoothing and sharpening is proposed in this paper. The model consists of two terms. One is smoothing and preserving edge term, the other is sharpening term. The role of the smoothing and preserving edge term is to smooth the flat regions of the image, not smooth or less smooth the edge of image. The sharpening term can enhance the edge of the image. Smoothing diffusion coefficient and sharpening diffusion coefficient control the degree of smoothing and sharpening. The diffusion coefficients are functions of gradient magnitude and dynamic threshold of image, where the dynamic threshold function is driven by a Poisson equation. The experimental results show that the smoothing and sharpening model has better properties than the smoothing and preserving edge model or the sharpening model, and is more suitable for extracting the features of the image.