为了实现高偏振度(HDOP)水下目标的清晰成像,分析了传统水下偏振成像模型,从Schechner模型出发,以偏振度定义为基础,提出了一种对后向散射光偏振度进行全局估计的偏振成像复原算法,该算法考虑了目标反射光的偏振度。进行了水槽偏振成像实验,对拍摄的三种目标在不同浓度浑浊水体中的偏振图像进行了复原。复原结果表明,与Schechner原算法相比,经所提偏振成像算法处理后,复原图像的增强测度值提高了90%以上,图像灰度的平均梯度、图像灰度的标准差和信息熵也都有提升。不同目标偏振图像的复原结果表明,所提算法不但适用于表面粗糙的低偏振度(LDOP)水下目标,对表面光滑的HDOP水下目标也能取得满意的复原效果。

In order to realize the clear imaging of underwater targets with high degree of polarization (HDOP), the traditional polarization imaging model is analyzed. Based on the Schechner polarization imaging model and the definition of polarization degree, a polarization imaging restoration algorithm is proposed to globally estimate the polarization degree of backscattered light, which considers the polarization degree of reflected light of targets. The polarization imaging experiment is conducted, in which the polarization images of three kinds of targets in turbid water with different concentrations are restored. The restoration results show that the measure of enhancement value of the restored image is increased by more than 90% compared to the original Schechner algorithm. Meanwhile, the average gradient, standard deviation and information entropy of image grey are also increased. The restoration results of different polarization images of targets show that the proposed algorithm is not only suitable for the underwater targets with low degree of polarization (LDOP) and rough surfaces, but also makes the underwater targets with HDOP and smooth surfaces gain satisfactory restoration effect.