For traditional dark channel prior (DCP) imaging through haze environments, intensity information acts as the carrier to acquire the reflective character of the dehazed target image. We introduce polarization as auxiliary information into the traditional DCP dehazed process for achieving better imaging performance that can improve target detection or target tracking. In this paper, a polarization imaging system with a split-amplitude structure is designed to enable real-time polarization acquisition of transient scenes. The experimental results show that besides descattering, the proposed method can also simultaneously obtain both light intensity and polarization information from the target. Compared with the traditional DCP method, which only utilizes intensity information as a carrier, a combination of intensity and polarization in the proposed method can effectively detect the target hidden in the background with similar reflectivity. Our investigation has potential application value for optical imaging in scattering environments.

We demonstrate an efficient polarization-difference imaging system in turbid conditions by using the Stokes vector of light. The interaction of scattered light with the polarizer is analyzed by the Stokes–Mueller formalism. An interpolation method is proposed to replace the mechanical rotation of the polarization axis of the analyzer theoretically, and its performance is verified by the experiment at different turbidity levels. We show that compared with direct imaging, the Stokes vector based imaging method can effectively reduce the effect of light scattering and enhance the image contrast.

Polarization of light is introduced into range-gated imaging (RGI) for target detection and recognition in turbid conditions. The polarimetric RGI system can obtain both intensity and polarization information on objects. The experimental results show that an intensity-based image, when the target part and the background part of an object have similar reflective characteristic, can reveal the contours of the object by minimizing the effect of backscattering from the medium, and a polarization-based image can highlight the target part by common-mode rejection of the background. Furthermore, intensity and polarization components are combined to describe the scene systematically. Four methods—Laplacian pyramid, discrete wavelet transform, contourlet transform and nonsubsampled contourlet transform—are used for image fusion. Favourable information represented in each image can be extracted from image fusion for target detection and recognition. Objective evaluation indices are applied to compare the performance of different image fusion methods.

浑浊介质中图像对比度的物理增强方法一直是研究热点, 目前学者们提出的距离选通成像、偏振差分成像和偏振距离选通成像均能提高图像的对比度, 但提高效果与成像距离的关系尚不明确. 本文分别利用以上三种成像方式及普通强度成像对处于不同浓度浑浊介质中的目标进行成像, 研究了图像强度和对比度随成像距离的变化情况. 结果表明: 从滤除的散射光强来看, 偏振距离选通成像最优, 而偏振差分成像在成像距离较远时优于距离选通成像; 三种成像方式滤除的散射光强值趋于稳定的阈值距离各不相同; 对比度改变相同量时, 偏振距离选通成像对应成像距离的变化量最大, 偏振差分成像次之, 强度成像最小, 且均与散射系数成反比. 本文对浑浊介质成像效果及机理的分析, 对进一步提高浑浊介质中目标的分辨及识别具有重要意义.

When light propagating through combustion flame environments, it deviates from original trajectory due to the scattering effect caused by combustion particulates. This behavior reduces the spatial positioning accuracy in tomographic radiation thermometry of flame. In order to overcome this problem, we investigate the characteristics of light transmission direction related to the wavelength theoretically and experimentally. The tomographic imaging system with number of four detection channels is built based on optoelectromechanical integration structure. The wavelength least affected by combustion flame is selected and employed to the established tomographic imager. With the aid of tomography data, the spatiotemporal evolutions of temperature can be further reconstructed by utilizing Planck law. These results demonstrate the effectiveness of proposed method and can be applied to the field of combustion diagnosis.