• Acta Physica Sinica
  • Vol. 69, Issue 18, 20200471 (2020)
Liu Bin, Zhao Peng-Xiang, Zhao Xia*, Luo Yue, and Zhang Li-Chao
Author Affiliations
  • School of Information and Communication Engineering, North University of China, Taiyuan 030051, China
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    Abstract

    Underwater optical imaging is the key technology to explore the underwater mystery. However, due to the absorption and backscattering effects of the media in the underwater environment, the image acquired by the detector will be severely degraded. In order to obtain the effective underwater scene information, it is necessary to restore the acquired underwater image. The restoration technology based on differential polarization is one of the main methods of restoring the underwater images, which can suppress the background scattered light by the common-mode suppression between orthogonal polarization graphs, thus realizing the restoration of underwater image. However, the relevant research shows that the restoration effect of this method is general for the underwater non-uniform light field. The main reason is that the estimation errors of polarization degree and background scattering intensity under the condition of the non-uniform underwater light field are large. Out of the above problem, in this paper we present the multiple aperture underwater imaging technology of fused polarization information. The method uses the camera array to realize the large virtual aperture imaging system, thus obtaining the wide-angle light field information, and then to fuse the depth information of the scene to realize the accurate estimation of background scattering light intensity and polarization degree under the condition of underwater non-uniform light field. The estimated parameter value can better reflect the global characteristics of the scene. Through the imaging experiments on the targets with different polarization degrees in the turbid underwater environment, comparing with the current advanced restoration algorithm, the results show that the proposed method can effectively solve the problems of background scattering and polarization degree significant estimation error caused by non-uniform underwater light field, and obtain high-quality restoration results. Through the contrast imaging experiment of the target in the underwater environment with different turbidity concentrations, the results show that with the increase of turbidity concentration of the water, the image recovery effect of the method in this paper is gradually weakened. However, it still has a good restoration effect at a large concentration. At the same time, imaging experiments are conducted on targets in underwater environments with different sediment concentrations. The results show that the method proposed in this paper can also obtain a better restoration image in the turbid water environment containing sediment.

    1 引 言

    水下环境中悬浮颗粒对光的散射和吸收导致光学成像系统的探测距离和成像质量等指标显著下降, 严重影响了后续水下目标的识别和分析[1,2], 因此水下图像的复原技术是光学成像领域的热点研究问题. 具体来说, 水下图像复原方法主要有数字图像处理复原、光学系统优化复原、多维度光学信息融合复原等[3-6]. 数字图像复原技术以水下成像的物理退化模型为基础, 依靠先验和假设等估计退化因子并反演退化过程以达到提升图像质量的效果, 其中典型的代表为暗通道先验技术、多通道融合技术[7,8]. 区别于数字图像处理复原方法, 另一类方法则侧重从光学系统优化设计和光学信息多维度融合方面出发达到水下图像复原的目标, 其中典型代表为多光谱融合复原、多视角信息融合复原、偏振光学成像复原等[9-12]. 基于偏振成像的复原方法利用散射光的偏振特性, 分离目标和背景光, 估计散射光强和透射系数, 达到抑制散射光提升图像质量的目的. 该方法散射介质类型实用性广, 细节保真度高, 特别是在高浓度散射介质中尤具优势, 因此在各领域中得到广泛应用.

    Copy Citation Text
    Bin Liu, Peng-Xiang Zhao, Xia Zhao, Yue Luo, Li-Chao Zhang. Multiple aperture underwater imaging algorithm based on polarization information fusion[J]. Acta Physica Sinica, 2020, 69(18): 184202-1
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    Received: Mar. 31, 2020
    Accepted: --
    Published Online: Jan. 5, 2021
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