Compact single-shot multispectral polarization imager through joint spectral-polarization encoding.

The technique of spectral polarization imaging (SPI) is a potent detection tool in various fields due to its ability to capture multi-dimensional information. However, existing SPI systems usually face challenges associated with architectural complexity and computational requirements, rendering them unsuitable for handheld, on-board, and real-time applications. Consequently, a compact single-shot multispectral polarization imager (CSMPI) is proposed, which employs a combined spectral-polarization encoding strategy to address the aforementioned issues.

Three-channel-switchable coded aperture snapshot multispectral polarization imaging.

An ingenious and compact snapshot multispectral polarization imaging method is proposed based on a new, to the best of our knowledge, three-channel-switchable spectral polarization coded aperture. We utilize the coded aperture to simultaneously select three-channel light components and encode them with specific spectrum-polarization coefficients. It enables easy retrieval of each channel's light component from the mixed information via polarization measurements and linear decoding operations.

Estimation and removal of backscattered light with nonuniform polarization information in underwater environments.

The nonuniform of polarization information of backscattered light has always been a neglected characteristic in polarization underwater imaging, but its accurate estimation plays an important role in the quality of imaging results. Traditional polarization imaging methods assume that the degree of polarization and angle of polarization of backscattered light are constant. In fact, the polarization information of backscattering light is gradual, this assumption makes traditional methods work only in a small area of the camera's field of view, in which the change of the polarization information of backscattered light can be ignored.

Enhancement of underwater vision by fully exploiting the polarization information from the Stokes vector.

Underwater imaging method based on polarization information is extremely popular due to its ability to effectively remove the backscattered light. The Stokes vector contains the information of both the degree and angle of polarization of the light wave. However, this aspect has been rarely utilized in image reconstruction.

Near-infrared monocular 3D computational polarization imaging of surfaces exhibiting nonuniform reflectance.

This paper presents a near-infrared (NIR) monocular 3D computational polarization imaging method to directly reconstruct the shape of surfaces exhibiting nonuniform reflectance. A reference gradient field is introduced to the weight constraints for globally correcting the ambiguity of the surface normal for a target with nonuniform reflectance. We experimentally demonstrated that our method can reconstruct the shape of surfaces exhibiting nonuniform reflectance in not only the near field but also the far field.

Polarization-based exploration for clear underwater vision in natural illumination.

Underwater imaging provides human vision system friendly images; however, it often suffers from severe image degradation. This research developed an underwater polarization imaging model, which considers the water scattering effect, as well as absorption effect. It fully explored the polarization information of the target scene that backscattered light is partially polarized and target light is unpolarized.

Deeply seeing through highly turbid water by active polarization imaging.

We hereby proposed and experimentally demonstrated an active polarization imaging technique, based on wavelength selection, for seeing through highly turbid water where targets are always visually lost. The method was realized by making use of the dependence of light scattering on wavelength in turbid water. Red light illumination was selected to minimize scattering occurring in light propagation and to guarantee accurate estimation of degree of polarization.

Active underwater descattering and image recovery.

Underwater imaging is a promising but challenging topic due to the scattering particles in water, which result in serious light attenuation. Therefore, underwater images suffer from low-contrast and low-resolution issues. In this study, in order to recover high-quality underwater images, the point spread functions (PSFs) are estimated by a slant-edge method.

Design of a circular polarization imager for contrast enhancement in rainy conditions.

We present the design of a circular polarization imager for imaging in rainy conditions, which is free from image calibration and correction before obtaining the orthogonal-state contrast image. The system employed a quarter wave plate in front of two Wollaston Prisms (WPs) to capture circularly polarized information and to acquire two orthogonally polarized images simultaneously on the charge coupled device (CCD). Along with the WPs, a reimaging part with multiaperture structure composed of two separate specialized reimaging modules, were implemented to make sure the two orthogonally polarized intensity images are exactly indicating the same scene.

Polarization characteristics of objects in long-wave infrared range.

Research on polarization characteristics of objects has become indispensable in the field of target detection. Though widespread studies on applying polarization to target detection and material identification exist, theoretical descriptions have varied widely in accuracy and completeness. Incomplete descriptions of polarization characteristics invariably result in poor demonstration of changes caused by macroscopic influence factors.

Polarimetric dehazing utilizing spatial frequency segregation of images.

A procedure for the detection and removal of haze from dense hazy images has been proposed. It involves the analysis on the content of low-spatial-frequency information of a scene. The image contaminated by haze is decomposed into different spatial frequency layers by the wavelet transform, by which the hazy parts of the image are focused on the low-frequency components.