Paradigm shifts in super-resolution techniques for remote sensing applications

Abstract

Super-resolution (SR) algorithms have now become a bottleneck for several remote sensing applications. SR is a technique that enhances minute details of the image by increasing spatial resolution of imaging systems. SR overcomes the problems of conventional resolution enhancement techniques such as introduction of noise, spectral distortion, and lack of clarity in the details of the image. In this paper, a survey has been conducted since the inception of SR algorithm till the latest state-of-the-art SR techniques to elucidate the importance of the SR algorithms that lead to paradigm shifts in the last two decades revolutionizing toward visually pleasing high-resolution image. Inspired from the natural images, the algorithms addressing the SR problems such as ill-posed, prior and regularization problem, inverse problem, multi-frame problem and illumination and shadow problem in remote sensing applications are analyzed. For an intuitive understanding of the paradigm shifts, publicly available images are tested with representative paradigm shift SR algorithms. The result of this paradigm shift analysis is done both qualitatively and quantitatively in terms of blurs in the image, pattern clarity, edge strength, and super-resolving capability. The convergence of the natural image to the remote sensed image is critically analyzed. The challenges with possible solutions for super-resolving the remote sensed image are recommended. On experimentation, it is found that deep learning-based SR algorithms produces visually pleasing images retaining sharp edges, enhanced spatial data, and clarity in feature representation while zooming at a certain level beyond interest.