Color Balance and Fusion for Underwater Image Enhancement

TLDR

The paper proposes a technique to enhance underwater images degraded by scattering and absorption. The method is a single‑image approach that blends a color‑compensated and a white‑balanced version of the degraded image, using weight maps to transfer edges and color contrast and a multiscale fusion strategy to suppress low‑frequency artifacts. Extensive evaluation shows that the enhanced images exhibit better exposedness of dark regions, improved global contrast and edge sharpness, and yield higher accuracy in downstream tasks such as segmentation and keypoint matching, largely independent of camera settings.

Abstract

We introduce an effective technique to enhance the images captured underwater and degraded due to the medium scattering and absorption. Our method is a single image approach that does not require specialized hardware or knowledge about the underwater conditions or scene structure. It builds on the blending of two images that are directly derived from a color-compensated and white-balanced version of the original degraded image. The two images to fusion, as well as their associated weight maps, are defined to promote the transfer of edges and color contrast to the output image. To avoid that the sharp weight map transitions create artifacts in the low frequency components of the reconstructed image, we also adapt a multiscale fusion strategy. Our extensive qualitative and quantitative evaluation reveals that our enhanced images and videos are characterized by better exposedness of the dark regions, improved global contrast, and edges sharpness. Our validation also proves that our algorithm is reasonably independent of the camera settings, and improves the accuracy of several image processing applications, such as image segmentation and keypoint matching.