Kernel Based Telegraph-Diffusion Equation for Image Noise Removal

The second-order partial differential equations have good performances on noise smoothing and edge preservation. However, for low signal-to-noise ratio (SNR) images, the discrimination between edges and noise is a challenging problem. In this paper, the authors propose a kernel based telegraph-diffusion equation (KTDE) for noise removal. In this method, a kernelized gradient operator is introduced in the second-order telegraph-diffusion equation (TDE), which leads to more effective noise removal capability. Experiment results show that this method outperforms several anisotropic diffusion methods and the TDE method for noise removal and edge preservation

Looking through the ground glass

We mitiate, and to an extent, motivate our discussion wave propagation through a rendom medium by asking whether we can view or image an object through a light scattering medium. We answer in the affirmative by arguing that the image-bearing ballistic component of light can be time-resolved with respect to the image-blurring diffusive component that has to traverse relatively much longer distance. This leads us to the question of diffusion of light or its absence (localization) in disordered media. We discuss some essential differences between photon localization vis-a-vis electron localization. One of these that makes photon localization much harder to realize experimentally is that the photon energy multilics the dielectric disorder in the Maxwell equation, as a result of which localization is missed in the limit of both the long wavelength (Rayleigh scattering) and the short wavelength (geometrical optics). The narrow 'window of localization' requires drastic enhancement of effective scattering which is possible by the coincidence of the Mie-resonant scattering and the Bragg-reflection (umklapp) conditions. Photon localization at microwave frequencies (as also the complete photon band gap) has alresdy been achieved by several workers. Localization at visible wavelengths is awaited. We also discuss some fundamental QED effects of photon localization, such as the suppression of spontaneous emission from an excited atom embedded in a random dielectric. We end possibility of a 'mobility-edge' laser