Reducing aliasing in images: a PDE-based diffusion revisited

In this paper, we introduce a new diffusion algorithm that can be used for reducing aliasing on both step edges and lines. It derives from the diffusion model of Perona and Malik, and works as an adaptive level-curve method in which diffusion is carried out in the normal direction of the gradient for step edges, while the eigenvalues of the Hessian matrix are used for lines. To get sharp images, we use high-pass filters to preserve as much as possible the high frequency content while diffusing. Experimental tests using grayscale and colour images show that our algorithm efficiently reduces aliasing.

► Reducing aliasing by an enhancement of the diffusion equation of Perona and Malik. ► Use of an inverse diffusivity for reducing aliasing on step edges in an image. ► Use of a high-pass filter in diffusion for preserving the high-frequency content. ► Use of the eigenvalues of the Hessian matrix for reducing aliasing on lines. ► Use of our diffusion model for reducing zipper effects in demosaicing algorithms.