Beyond the current noise limit in imaging through turbulent medium

TL;DR

This paper introduces a novel genetic algorithm-based method for accurately determining image shifts in turbulent media, enabling high-resolution imaging even with very faint objects, surpassing current noise limits.

Contribution

We develop a highly efficient shift determination technique using a genetic algorithm that improves image reconstruction in turbulent conditions, even with minimal object brightness.

Findings

Successfully recovered spatial distribution of objects 2% brighter than background

Extended the limits of shift-and-add imaging in turbulent media

Applicable to optical and infrared imaging, and low-light stabilization

Abstract

Shift-and-add is an approach employed to mitigate the phenomenon of resolution degradation in images acquired through a turbulent medium. Using this technique, a large number of consecutive short exposures is registered below the coherence time of the atmosphere or other blurring medium. The acquired images are shifted to the position of the brightest speckle and stacked together to obtain high-resolution and high signal-to-noise frame. In this paper we present a highly efficient method for determination of frames shifts, even if in a single frame the object cannot be distinguished from the background noise. The technique utilizes our custom genetic algorithm, which iteratively evolves a set of image shifts. We used the maximal energy of stacked images as an objective function for shifts estimation and validate the efficiency of the method on simulated and real images of simple and complex sources. Obtained results confirmed, that our proposed method allows for the recovery of spatial distribution of objects even only 2% brighter than their background. The presented approach extends significantly current limits of image reconstruction with the use of shift-and-add method. The applications of our algorithm include both the optical and the infrared imaging. Our method may be also employed as a digital image stabilizer in extremely low light level conditions in professional and consumer applications.