UIF: An Objective Quality Assessment for Underwater Image Enhancement

TL;DR

This paper introduces UIF, an objective quality assessment metric for underwater image enhancement that combines statistical features related to naturalness, sharpness, and structure, validated on a new large-scale database.

Contribution

The paper proposes a novel UIF metric that effectively evaluates underwater image enhancement quality using statistical features and support vector regression, filling a gap in existing methods.

Findings

UIF outperforms existing quality metrics in experiments

A large-scale UIE database (UIED) is established for benchmarking

The method effectively assesses visual improvements in underwater images

Abstract

Due to complex and volatile lighting environment, underwater imaging can be readily impaired by light scattering, warping, and noises. To improve the visual quality, Underwater Image Enhancement (UIE) techniques have been widely studied. Recent efforts have also been contributed to evaluate and compare the UIE performances with subjective and objective methods. However, the subjective evaluation is time-consuming and uneconomic for all images, while existing objective methods have limited capabilities for the newly-developed UIE approaches based on deep learning. To fill this gap, we propose an Underwater Image Fidelity (UIF) metric for objective evaluation of enhanced underwater images. By exploiting the statistical features of these images, we present to extract naturalness-related, sharpness-related, and structure-related features. Among them, the naturalness-related and sharpness-related features evaluate visual improvement of enhanced images; the structure-related feature indicates structural similarity between images before and after UIE. Then, we employ support vector regression to fuse the above three features into a final UIF metric. In addition, we have also established a large-scale UIE database with subjective scores, namely Underwater Image Enhancement Database (UIED), which is utilized as a benchmark to compare all objective metrics. Experimental results confirm that the proposed UIF outperforms a variety of underwater and general-purpose image quality metrics.