基于斯托克斯参量的水下主动偏振去散射研究

Research on Underwater Active Polarization Descattering Based on Stokes Vectors

摘要:

受浑浊水体自身吸收与微颗粒散射的影响，水下光学成像面临成像距离短、像质差等问题。一种基于斯托克斯参量的主动偏振成像模型被应用到水下成像去散射过程中，有效提升了目标成像探测的清晰度。相比于被动偏振成像模型，引入主动光源可以实现对入射光的偏振调制，由此可以充分挖掘目标反射光与介质光的偏振特征差异进而实现分离选通。改进的主动偏振去散射模型利用了目标反射光的偏振共模抑制效应，借助偏振斯托克斯参量 S₂ 分量实现了介质光偏振角与偏振度全局分布的准确估算。同时引入图像质量评价参数对比度 contrast 作为反馈参量，通过迭代计算实现背景噪声的最大化滤除。不同散射程度、不同类型目标的水下成像实验表明：相比于传统主动偏振成像方法，改进后的成像模型可大幅提升水下目标的图像质量，特别是强散射环境下的图像 contrast 提升超 2 倍以上。该项工作为利用偏振信息进行水下图像去散射与目标重建提供了新思路。

Abstract:

Affected by absorption of turbid water and scattering of micro-particles，underwater optical imaging faces the problems of short imaging distance and poor image quality. In this paper，an improved active polarization imaging method is introduced into the descattering process to achieve higher imaging contrast. Compared with the passive polarization imaging model，the introduction of an active light source can perform polarization modulation on the incident light，which better serves the underwater optical transmission model to separate and solve the target information. For the first time，the S₂ component of Stokes vectors based on the common mode suppression is used to eliminate the interference of the target information. Therefore，the polarization degree of backscattered light is accurately reconstructed. Meanwhile，introducing contrast as feedback optimization is to achieve determination of optimal parameters. The imaging experiments with different types of targets prove the effectiveness of the method under various turbidities water. The imaging contrast is improved by more than 2 times in strong scattering water. This work provides a new idea for introducing the polarization information into the enhancement and restoration of the target information.