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Journal of ZheJiang University (Engineering Science)  2026, Vol. 60 Issue (4): 800-811    DOI: 10.3785/j.issn.1008-973X.2026.04.012
    
Underwater image enhancement algorithm based on feature refinement and attention-augmented reconstruction
Gang WAN1,2(),Xiaobo WANG3,Gang SHI3,Dezhen YE1,2,Sisi ZHU1,2,Fan SI3,*()
1. Hubei Technology Innovation Center for Smart Hydropower, Wuhan 430000, China
2. China Yangtze Power Co. Ltd, Yichang 443000, China
3. Changjiang Survey, Planning, Design and Research Co. Ltd, Wuhan 430010, China
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Abstract  

Aiming at the degradation of underwater images due to light propagation attenuation, scattering, and dissolved suspended matter, a novel underwater image enhancement network integrating a spatial-wise refined feature Transformer (SRFT) module and a channel-wise feature attention enhanced reconstructed Transformer (CFART) module was proposed. Serialization processing and positional encoding on underwater image sequences were performed by the SRFT module and four-layered spatial self-attention mechanisms were applied to capture global degradation differences while establishing long-range feature dependencies. In the CFART module, features were projected via heterogeneous convolutional kernels and then fed into a multi-head self-attention module through channel fusion. And feature information was reconstructed using multilayer perceptron layers with residual connections. Experimental results showed that the proposed algorithm effectively improved issues such as color shift, blurriness, and low contrast issues in underwater images. In terms of objective evaluation metrics, the proposed algorithm outperformed similar methods with MSE of 253.558, PSNR of 25.421, Entropy of 7.488, and UIQM of 4.461. It also demonstrated significant advantages in SSIM and UCIQE tests with SSIM of 0.893 and UCIQE of 0.592. Subjective visual assessments further confirmed that the proposed algorithm provided excellent color correction and detail restoration capabilities for degraded underwater images. By optimizing the quality of underwater images, the proposed algorithm helps to enhance the precision and efficiency of seabed investigations and assessments.



Key wordsunderwater image enhancement      image quality degradation      self-attention mechanism      spatial-wise refined feature      enhanced reconstructed Transformer model     
Received: 10 May 2025      Published: 19 March 2026
CLC:  TP 391  
Fund:  湖北省智慧水电技术创新中心2023年开放研究基金资助项目(SDCXZX-JJ-2023-09);湖北省教育厅科学研究计划重点项目(D20231304);西藏自治区科技计划重大专项(XZ202402ZD0001);深地国家科技重大专项(2024ZD1001003);国家重点研发计划资助项目(2022YFB4703400).
Corresponding Authors: Fan SI     E-mail: wan_gang@ctg.com.cn;2024710585@yangtzeu.edu.cn
Cite this article:

Gang WAN,Xiaobo WANG,Gang SHI,Dezhen YE,Sisi ZHU,Fan SI. Underwater image enhancement algorithm based on feature refinement and attention-augmented reconstruction. Journal of ZheJiang University (Engineering Science), 2026, 60(4): 800-811.

URL:

https://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2026.04.012     OR     https://www.zjujournals.com/eng/Y2026/V60/I4/800


基于特征细化与注意力增强重构的水下图像增强算法

针对水下图像因光传播衰减、散射和水中溶解悬浮物等因素导致的图像质量退化问题,提出基于空间细化特征自注意力(SRFT)与通道特征注意力增强重构Transformer (CFART)模块的水下图像增强网络模型. SRFT模块对水下图像进行序列化处理和位置编码,采用4层空间自注意力提取全局退化差异,建立长程特征依赖关系. CFART模块采用异构卷积核投影特征,随后经通道融合输入至多头自注意力模块,并利用多层感知机与残差结构重构特征信息. 实验结果表明,本研究算法能有效改善水下图像中存在的颜色偏移、模糊以及低对比问题. 在客观评价指标方面,本算法的MSE (253.558)、PSNR (25.421)、Entropy (7.488)和UIQM (4.461)均优于同类方法;在SSIM(0.893)和UCIQE (0.592)上也表现出明显优势;主观视觉评价进一步证实本研究算法对退化的水下图像具有良好的色彩校正与细节恢复能力. 本研究算法可以优化水下图像质量,有助于提升海底调查与评估工作的精度与效率.


关键词: 水下图像增强,  图像质量退化,  自注意力机制,  空间细化特征,  增强重构Transformer模型 
Fig.1 Overall structure of underwater image enhancement network
Fig.2 Spatial-wise refined feature self-attention module
Fig.3 Channel-wise feature attention enhanced reconstructed module
Fig.4 Overall architecture of underwater image enhancement network based on feature refinement and attention-augmented reconstruction
Fig.5 Subjective visual comparison results of various algorithms for complex underwater image enhancement
Fig.6 Subjective visual comparison results of various algorithms for simple underwater image enhancement
Fig.7 Comparison results of magnification for different types of underwater images
Fig.8 Testing results of various algorithms on UIEB dataset
算法MSE↓PSNR↑SSIM↑EntropyUIQM↑UCIQE↑
原始图像1609.68217.4910.8646.8874.1170.542
HE[7]2558.82814.9310.7517.1414.3080.604
CLAHE[8]1502.20117.0080.8437.2084.3370.565
DEFOG[6]2511.26715.6080.8696.9254.3250.553
Ucolor[25]352.19322.9110.8987.2344.3890.562
URST[26]394.47622.7050.9057.3214.1770.585
U-Shape[18]334.99224.2930.8817.2844.4180.571
WFFP[27]968.71318.2710.7356.7924.2010.601
Spectroformer[28]774.80619.3880.6406.3143.95960.552
本研究算法253.55825.4210.8937.4884.4610.592
Tab.1 Objective evaluation metrics of image quality for various algorithms on LSUI
算法MSE↓PSNR↑SSIM↑EntropyUIQM↑UCIQE↑
原始图像1751.35817.2530.7546.8943.9670.539
HE[7]1868.49116.6210.7377.1674.2940.664
CLAHE[8]1216.22618.1940.7137.3194.4240.567
DEFOG[6]2730.89615.2430.7096.8414.2310.553
Ucolor[25]868.58520.1510.7487.3684.2110.608
URST[26]864.72520.1780.7697.4154.3590.584
U-Shape[18]734.62620.8810.7097.2624.3970.578
WFFP[27]828.48518.9490.7917.7494.2130.609
Spectroformer[28]1546.45516.2350.6846.5523.7230.521
本研究算法438.48021.7110.7927.3014.4430.579
Tab.2 Objective evaluation metrics of image quality for various algorithms on UIEB
Fig.9 Subjective visual comparison of ablation experiment across different scenarios
算法MSE↓PSNR↑SSIM↑Entropy↑UIQM↑UCIQE↑
基准334.99224.2930.8817.2844.4180.571
基准+特征
细化模块
290.06424.7590.7797.2494.4610.569
基准+重构
增强模块
310.60424.4030.7657.2154.4050.564
本研究算法253.55825.4210.8937.4884.4710.592
Tab.3 Objective evaluation metrics of image quality for ablation experiment
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