Abstract
Images taken under water usually suffer from the problems of quality degradation, such as low contrast, blurring details, color deviations, non-uniform illumination, etc. As an important problem in image processing and computer vision, the restoration and enhancement of underwater image are necessary for numerous practical applications. Over the last few decades, underwater image restoration and enhancement have been attracting an increasing amount of research effort. However, a comprehensive and in-depth survey of related achievements and improvements is still missing, especially the survey of underwater image dataset which is a key issue in underwater image processing and intelligent application. In this exposition, we first summarize more than 120 studies about the latest progress in underwater image restoration and enhancement, including the techniques, datasets, available codes, and evaluation metrics. We analyze the contributions and limitations of existing methods to facilitate the comprehensive understanding of underwater image restoration and enhancement. Furthermore, we provide detailed objective evaluations and analysis of the representative methods on five types of underwater scenarios, which verifies the applicability of these methods in different underwater conditions. Finally, we discuss the potential challenges and open issues of underwater image restoration and enhancement and suggest possible research directions in the future.
Highlights
Underwater optical imaging systems mainly include an optical camera, or adopt techniques such as polarization, stereo/panoramic, and spectral imaging [1]–[4]
When light propagates through the water, the absorption and scattering determined by the internal optical property (IOP) of the water affect the process of underwater imaging [5]
The contributions of this paper are listed as follows: (i) we refer to more than 120 related studies and summarize existing techniques, datasets, and evaluation metrics, which aims to help researchers to understand the development of this research area; (ii) we conduct detailed objective evaluations and comprehensive performance analysis for the representative methods under classical five types of underwater scenes, which can guide the selection of the most appropriate method for practical cases; (iii) we summarize the datasets widely used in the representative researches, which is the most concerned issue in underwater image artificial intelligent exploitation; and (iv) we look into several open issues of underwater image restoration and enhancement, which sheds light on potential research directions in future
Summary
Underwater optical imaging systems mainly include an optical camera, or adopt techniques such as polarization, stereo/panoramic, and spectral imaging [1]–[4]. An in-depth exploration of underwater restoration and enhancement methods, image quality evaluation techniques and related datasets is still missed. The contributions of this paper are listed as follows: (i) we refer to more than 120 related studies and summarize existing techniques, datasets, and evaluation metrics, which aims to help researchers to understand the development of this research area; (ii) we conduct detailed objective evaluations and comprehensive performance analysis for the representative methods under classical five types of underwater scenes, which can guide the selection of the most appropriate method for practical cases; (iii) we summarize the datasets widely used in the representative researches, which is the most concerned issue in underwater image artificial intelligent exploitation; and (iv) we look into several open issues of underwater image restoration and enhancement, which sheds light on potential research directions in future.
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