融合偏振信息的多孔径水下成像算法

Multiple aperture underwater imaging algorithm based on polarization information fusion

水下光学成像是探索水下奥秘的关键技术,但是环境中介质吸收和背向散射效应会造成图像严重退化.基于差分偏振的复原技术是水下图像复原技术的主要方法之一,通过正交偏振图之间的共模抑制实现背景散射光的抑制,但是相关研究表明该方法对于非均匀光场等情况的恢复效果一般,其原因主要在于非均匀光场条件下偏振度和强度的估计误差.针对上述问题,本文提出融合偏振信息的多孔径水下成像技术,该方法利用相机阵列实现虚拟大孔径成像系统,从而获取广角光场信息,进而融合场景的深度信息实现背景散射和偏振度的精确估计,估计参数值能更好地反映场景的全局特征.对浑浊水下环境中不同偏振度目标进行成像实验,与目前先进的复原算法进行对比,结果表明,本文方法能够有效克服水下非均匀光场带来的问题,得到高质量的复原结果.

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.