An important task in image processing is the process of filling in missing parts of damaged images based on the information obtained from the surrounding areas. It is called inpainting. The goals of inpainting are numerous such as removing scratches in old photographic image, removing text and logos, restoration of damaged paintings. In this paper we present a nonlinear diffusion model for image inpainting based on a nonlinear partial differential equation as first proposed by Perona and Malik in [8]. In our previous work [3] the existence, uniqueness and regularity of the solution for the proposed mathematical model are established in an Hilbert space. The discretization of the partial differential equation of the proposed model is performed using finite elements method and finite differences method. For finite differences method our model is very simple to implement, fast, and produces nearly identical results to more complex, and usually slower, known methods. However for finite elements method we observe that it requires large computational cost, especially for high-resolution images. To avoid this slowing problem, domain decomposition algorithm has been proposed, aiming to split one large problem into many smaller problems. To illustrate the effective performance of our method, we present some experimental results on several images.

Image inpainting is an important research area in image processing. Its main purpose is to supplement missing or damaged domains of images using information from surrounding areas. This step can be performed by using nonlinear diffusive filters requiring a resolution of partial differential evolution equations. In this paper, we propose a filter defined by a partial differential nonlinear evolution equation with spatial fractional derivatives. Due to this, we were able to improve the performance obtained by known inpainting models based on partial differential equations and extend certain existing results in image processing. The discretization of the fractional partial differential equation of the proposed model is carried out using the shifted Grünwald–Letnikov formula, which allows us to build stable numerical schemes. The comparative analysis shows that the proposed model produces an improved image quality better or comparable to that obtained by various other efficient models known from the literature.

Abstract:The generation process of medical images is inevitably accompanied by a certain noise which degrades the quality of the image and assigns the final clinical diagnosis. Therefore, the denoising step plays an important role in the treatment of medical images in order to prepare the steps of diagnosis and therapy. In this paper, we propose a nonlinear diffusion model for denoising of large size images. The numerical approach to this problem is based on an algorithm combining the methods of finite element and of domain decomposition. Numerical simulations show that the proposed algorithm is a useful alternative for the treatment of degraded images large size.

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