Mathematical Approaches to Digital Image Inpainting

Image inpainting process is used to restore the damaged image or missing parts of an image. This technique is used in some applications, such as removal of text in images and photo restoration. There are different types of methods used in image inpainting, such as non-inear partial differential equations(PDEs), wavelet transformation and framelet transformation. We studied the usage of the current image inpainting methods and solved the Poisson equation using a five-point stencil method. We used a modified five-point stencil method to solve the same equation. It gave better results than the standard five-point stencil method. Using modified five-point stencil method results as the initial condition, we solved the iterative linear and non-linear diffusion PDE. We considered different types of diffusion conductivity and compared their results. When compared with PSNR values, the iterative linear diffusion PDE method gave the best results where as constant diffusion conductivity PDE gave the worst result. Furthermore, inverse diffusion conductivity PDE had given better results than that of the constant diffusion PDE. However, it was worse than the Gaussian and Lorentz diffusion conductivity PDE. Gaussian and Lorentz diffusion conductivity iterative linear PDE had given a better result for image inpainting. When we use any inpainting technique, we cannot restore the original image. We studied the relationship between the error of the image inpainting and the inpainted domain. Error is proportional to the value of the Greens function. There are two types of methods to find the Greens function. The first method is solving a Poisson equation for a different shape of domain, such as a circle, ellipse, triangle and rectangle. If the inpainting domain has a different shape, then it is difficult to find the error. We used the conformal mapping method to find the error. We also developed a formula for transformation from any polygon to the unit circle. Moreover, we applied the Schwarz Christoffel transformation to transform from the upper half plane to any polygon

A New Multiscale Representation for Shapes and Its Application to Blood Vessel Recovery

In this paper, we will first introduce a novel multiscale representation (MSR) for shapes. Based on the MSR, we will then design a surface inpainting algorithm to recover 3D geometry of blood vessels. Because of the nature of irregular morphology in vessels and organs, both phantom and real inpainting scenarios were tested using our new algorithm. Successful vessel recoveries are demonstrated with numerical estimation of the degree of arteriosclerosis and vessel occlusion.Comment: 12 pages, 3 figure

Image inpainting based on self-organizing maps by using multi-agent implementation

AbstractThe image inpainting is a well-known task of visual editing. However, the efficiency strongly depends on sizes and textural neighborhood of “missing” area. Various methods of image inpainting exist, among which the Kohonen Self-Organizing Map (SOM) network as a mean of unsupervised learning is widely used. The weaknesses of the Kohonen SOM network such as the necessity for tuning of algorithm parameters and the low computational speed caused the application of multi- agent system with a multi-mapping possibility and a parallel processing by the identical agents. During experiments, it was shown that the preliminary image segmentation and the creation of the SOMs for each type of homogeneous textures provide better results in comparison with the classical SOM application. Also the optimal number of inpainting agents was determined. The quality of inpainting was estimated by several metrics, and good results were obtained in complex images

A Unified Surface Geometric Framework for Feature-Aware Denoising, Hole Filling and Context-Aware Completion

Technologies for 3D data acquisition and 3D printing have enormously developed in the past few years, and, consequently, the demand for 3D virtual twins of the original scanned objects has increased. In this context, feature-aware denoising, hole filling and context-aware completion are three essential (but far from trivial) tasks. In this work, they are integrated within a geometric framework and realized through a unified variational model aiming at recovering triangulated surfaces from scanned, damaged and possibly incomplete noisy observations. The underlying non-convex optimization problem incorporates two regularisation terms: a discrete approximation of the Willmore energy forcing local sphericity and suited for the recovery of rounded features, and an approximation of the l(0) pseudo-norm penalty favouring sparsity in the normal variation. The proposed numerical method solving the model is parameterization-free, avoids expensive implicit volumebased computations and based on the efficient use of the Alternating Direction Method of Multipliers. Experiments show how the proposed framework can provide a robust and elegant solution suited for accurate restorations even in the presence of severe random noise and large damaged areas

Trends in Mathematical Imaging and Surface Processing

Motivated both by industrial applications and the challenge of new problems, one observes an increasing interest in the field of image and surface processing over the last years. It has become clear that even though the applications areas differ significantly the methodological overlap is enormous. Even if contributions to the field come from almost any discipline in mathematics, a major role is played by partial differential equations and in particular by geometric and variational modeling and by their numerical counterparts. The aim of the workshop was to gather a group of leading experts coming from mathematics, engineering and computer graphics to cover the main developments