Imaging Techniques Through Unfavorable Media

Abstract

This is a review style paper on the work done at UNSW Canberra on various imaging techniques to overcome transmission media limitation. First, we describe the problem of imaging through a medium, then look at possible ways of removing adverse effects. In this endeavor, temporal and spatial redundancies and diversities are key to achieving the retrieval of a latent image. Be it an astronomical observation or a reconstructed internal organ, the end goal is to reconstruct a likeness of the original object with as much fidelity as available from the often-incomplete imaging data. In the case of temporal redundancies and diversities, the reconstruction method relies on the acquisition of successive images of the same object subject to the variations in the transmission medium, whilst assuming that the object remains static and that the only variations are caused by the medium. The reconstruction is then a matter of modelling the statistics of the variations and factoring them out. An alternative to this approach is to exploit the spatial redundancies and diversities offered by a light field imaging system, where the image of the object can be simultaneously acquired from slightly different directions and different focus. Light field imaging is in fact a type of Shack-Hartmann wavefront sensor with more pixels. This lends itself to imaging through atmospheric turbulence and imaging through wavy water surfaces.