A retinex-based enhancing approach for single underwater image

TLDR

Underwater imaging suffers from color distortion, under‑exposure, and fuzz due to light absorption and scattering. The study proposes a retinex‑based method to enhance single underwater images. The method applies color correction, a variational retinex decomposition optimized via alternating direction, and separate enhancement of reflectance and illumination before recombining them. Results show improved color, brighter dark areas, preserved naturalness, sharper edges, and the approach generalizes to other degraded images such as sandstorm scenes.

Abstract

Since the light is absorbed and scattered while traveling in water, color distortion, under-exposure and fuzz are three major problems of underwater imaging. In this paper, a novel retinex-based enhancing approach is proposed to enhance single underwater image. The proposed approach has mainly three steps to solve the problems mentioned above. First, a simple but effective color correction strategy is adopted to address the color distortion. Second, a variational framework for retinex is proposed to decompose the reflectance and the illumination, which represent the detail and brightness respectively, from single underwater image. An effective alternating direction optimization strategy is adopted to solve the proposed model. Third, the reflectance and the illumination are enhanced by different strategies to address the under-exposure and fuzz problem. The final enhanced image is obtained by combining use the enhanced reflectance and illumination. The enhanced result is improved by color correction, lightens dark regions, naturalness preservation, and well enhanced edges and details. Moreover, the proposed approach is a general method that can enhance other kinds of degraded image, such as sandstorm image.