A Practical Calibration Method for RGB Micro-Grid Polarimetric Cameras

Rodriguez, Joaquin; Voon, Lew F.C. Lew Yan; Martins, Renato; Morel, Olivier

doi:10.1109/lra.2022.3192655

Cited by 6 publications

(12 citation statements)

References 23 publications

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“…In this context, Ono et al 22 presented a white balance algorithm for RGB-polarization sensors based on the achromaticity of the Stokes vector in the visible spectrum. Rodriguez et al 7 relaxed the experiment setup to calibrate micro-grid color-polarization sensors to achieve a flatfield response in all the polarization parameter images. Wen et al 35 solved the separation of specular from diffuse reflections with a model-based optimization strategy.…”

Section: Image Enhancementmentioning

confidence: 99%

“…This module is an implementation of the polarimetric camera calibration algorithm described in Ref. 7. The calibration algorithm is used to compute a series of matrices that are applied by a correction function to rectify the measurement errors due to manufacturing imperfections.…”

Section: Polarimetric Camera Calibration Modulementioning

confidence: 99%

“…Therefore, the effects of a linear polarizer in front of a normal camera can be simulated by computing Eq. (7). Thus in this functionality, the inputs are a raw image from the camera and the orientation of the filter θ that one would like to simulate.…”

Section: Polarization Processing Algorithmsmentioning

confidence: 99%

“…(a) Micro-grid sensor scheme with four super-pixels with polarizer orientations of 0 deg, 45 deg, 90 deg, and 135 deg arranged following a Bayer pattern of a typical RGB-polarization sensor 7 . (b) Sketch of the interaction between a light ray coming from the air with refractive index n1 and an object with refractive index n2.…”

Section: Polarization Backgroundmentioning

confidence: 99%

“…In some cases, this implies having high-quality measurements independently of the camera used, which can be achieved through camera calibration 5 – 7 , 57 In others, the improvement can be related to removing highly bright, specular reflections, requiring a separation between this type of reflection from the diffuse ones 22 , 58 , 59 . In more complex cases, the background structure needs to be recovered when an atmospheric phenomenon is present such as mist or fog, as shown for some examples in Fig.…”

Section: Related Workmentioning

confidence: 99%

See 4 more Smart Citations

Pola4All: survey of polarimetric applications and an open-source toolkit to analyze polarization

Rodriguez,

Lew-Yan-Voon,

Martins

et al. 2024

J. Electron. Imag.

Self Cite

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Polarization information of the light can provide rich cues for computer vision and scene understanding tasks, such as the type of material, pose, and shape of the objects. With the advent of new and cheap polarimetric sensors, this imaging modality is becoming accessible to a wider public for solving problems, such as pose estimation, 3D reconstruction, underwater navigation, and depth estimation. However, we observe several limitations regarding the usage of this sensorial modality, as well as a lack of standards and publicly available tools to analyze polarization images. Furthermore, although polarization camera manufacturers usually provide acquisition tools to interface with their cameras, they rarely include processing algorithms that make use of the polarization information. In this work, we review recent advances in applications that involve polarization imaging, including a comprehensive survey of recent advances on polarization for vision and robotics perception tasks. We also introduce a complete software toolkit that provides common standards to communicate with and process information from most of the existing micro-grid polarization cameras on the market. The toolkit also implements several image processing algorithms for this modality, and it is publicly available on GitHub.

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Section: Image Enhancementmentioning

confidence: 99%

Section: Polarimetric Camera Calibration Modulementioning

confidence: 99%

Section: Polarization Processing Algorithmsmentioning

confidence: 99%

Section: Polarization Backgroundmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

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Pola4All: survey of polarimetric applications and an open-source toolkit to analyze polarization

Rodriguez,

Lew-Yan-Voon,

Martins

et al. 2024

J. Electron. Imag.

Self Cite

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Camera-based safety system for collaborative assembly

Chebotareva,

Mustafin,

Safin

et al. 2024

J Intell Manuf

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Sub-percent characterization and polarimetric performance analysis of commercial micro-polarizer array detectors

Stockmans,

Scheinowitz,

van der Linden

et al. 2024

Polarization: Measurement, Analysis, and Remote Sensing XVI

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Polarization imaging can yield crucial information in multiple applications of remote sensing, such as characterization of clouds, aerosols, and the Aurora Borealis. Some applications require sub-percent polarimetric sensitivity and accuracy in determining the Stokes parameters, which can be a challenge to attain. In 2018, Sony released a low-cost CMOS-based imaging chip with integrated micro-polarizer array for general polarization measurements. We implement the calibration steps required for these Sony chips to reach sub-percent polarimetric accuracies. To analyze their performances, we have compared the characteristics of four different detector packages by three manufacturers housing either the monochromatic version or the RGB color variant. We present a comprehensive overview of the effects that these characteristics have on the polarimetric performance of the camera. They include dark noise, behavior over different gain settings, detector/pixel artifacts, and polarimetric effects determined by polarizer extinction ratios, polarizer orientations, and accuracy of polarimetric zero points due to differential pixel gains. In addition to calibrations using unpolarized light and fully linearly polarized light, we assess the polarimetric sensitivity within a tilting and rotating glass-plate set-up. We discuss the benefits of adding a rotating half-wave plate as an additional temporal modulator to generically mitigate some of the detector effects, and achieve better polarimetric sensitivity/accuracy albeit at the expense of lower temporal resolution. We conclude by presenting and discussing the polarimetric limits to which we were able to calibrate the detector effects for practical purposes. By reaching a compound absolute polarimetric uncertainty of less than a percent, these very compact, low-cost detectors are enabled for a multitude of scientific goals.

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A Practical Calibration Method for RGB Micro-Grid Polarimetric Cameras

Cited by 6 publications

References 23 publications

Pola4All: survey of polarimetric applications and an open-source toolkit to analyze polarization

Pola4All: survey of polarimetric applications and an open-source toolkit to analyze polarization

Camera-based safety system for collaborative assembly

Sub-percent characterization and polarimetric performance analysis of commercial micro-polarizer array detectors

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