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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe, Japan (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - A Novel Approach to Underwater De-Scattering Based on Sparse and Low-Rank Matrix Decomposition
摘要： The images captured in turbid water suffer from severe visual degradation due to the dramatic scattering effects caused by abundant large suspended particles. This paper propose a novel underwater image de-scattering approach with low complexity, which can separate the scattering component from the image by using the sparse and low-rank matrix decomposition. The experimental results show that the proposed approach can enhance the global image contrast effectively. Additionally, this approach does not require specialized hardware or prior knowledge about the underwater environment; it is suitable for the underwater imaging system in real time.
关键词： turbid water,low-rank matrix decomposition,de-scattering,underwater image
更新于2025-09-23 15:23:52
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Monte Carlo based model for diffuse reflectance from turbid media for the diagnosis of epithelial dysplasia
摘要： Diffuse reflectance from biological tissue has been widely used in diagnostic oncology for characterizing biochemical and morphological changes in epithelial tissue. However, computational complexity and time consumption involved in the extraction of absorption and scattering properties of tissues from diffuse reflectance reduce its potentiality for the effective diagnosis in a clinical setup. In this regard, a simple and accurate empirical equation for diffuse reflectance from a turbid medium was developed. A diffuse reflectance lookup table was generated using Monte Carlo simulations of all the optical properties typical of soft tissues in the visible and near infrared region of the spectrum for a semi-infinite medium. The generated lookup table was used to extract an empirical equation for diffuse reflectance using the surface fitting method. The proposed equation was tested with simulations and tissue phantom validation studies. The accuracy of the proposed empirical equation is tenfold higher than the diffusion approximation method. The uniqueness of the present method lies in its reliability even at extremities.
关键词： turbid medium,empirical model,Monte Carlo,epithelial dysplasia,diffuse reflectance
更新于2025-09-23 15:23:52
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Pseudo-polarimetric method for dense haze removal
摘要： The scattering and absorption by the existing particles in turbid media severely degrading the image quality and decreasing the visibility distance, especially in dense turbid media. In this paper, we investigate the polarization property of hazy images in dense turbid media, and we propose a simple pseudo-polarimetric dehazing method for dense haze removal, which only requires a single image captured by the detector. By our proposed method, two orthogonal polarization sub-images are derived from the single original image, and then, based on these two sub-images, one can obtain the recovered image by using traditional polarimetric method. The real-word experimental results verify that, for the dense haze, our method based on a single image could have a comparable or better performance compared to the traditional polarimetric dehazing method with multiple images captured at different polarization states.
关键词： polarimetric imaging,Polarization,imaging through turbid media
更新于2025-09-23 15:22:29
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Validation of MODIS-Aqua bio-optical algorithms for phytoplankton absorption coefficient measurement in optically complex waters of El Rincón (Argentina)
摘要： El Rincón is a highly productive area in the inner-shelf of the Argentine Sea, southern Buenos Aires Province (39°S–62.5°W; 41.5°S–60°W), regarded as the habitat for commercially valuable ?sh species and important for local artisanal ?sheries. The aims of this work were to characterize for the ?rst time the in situ absorption coe?cient of phytoplankton (aph(λ)) in relation to phytoplankton composition and chlorophyll-a (Chl-a) concentration, and to evaluate the satellite retrieval of aph(443) using two atmospheric correction algorithms and three bio-optical semi-analytical algorithms in order to de?ne which is more suitable for the study area. A total of 28 oceanographic cruises were performed between November 2013 and March 2017 and the sampling included physical variables (temperature, salinity, suspended particulate matter, SPM), Chl-a, phytoplankton absorption and composition. The phytoplankton community was mainly dominated by chain-forming diatoms from the microplankton size class (40–80%), while a single coccolithophore, Gephyrocapsa oceanica (cell diameter < 10 μm) was a key component (up to 40%) of the nanoplankon. In situ Chl-a (mean 1.8 mg m?3) and aph(443) (mean 0.052 m?1) generally covariated with no clear seasonality. Their correlation was rather low (R2 = 0.52) and with high scattering, in agreement with the high interannual variability of phytoplankton composition. Further, the relative low mean speci?c absorption coe?cient of phytoplankton (aph*(443), 0.032 m2 (mg Chl-a)?1) and (aph*(676), 0.014 m2 (mg Chl-a)?1) denoted the presence of big cells and pigment packaging e?ect. Aside from the optical complexity of these waters, reasonable results were found using the Quasi Analytical Algorithm in retrieving aph coe?cient (R2 = 0.55, Bias = 19%) and switching the atmospheric correction algorithm depending on the distance to the coast, the depth and turbidity. The results found in this paper present for the ?rst time the phytoplankton composition and absorption of algal material characteristics and the derived implication on the performance of bio-optical algorithms in the optically complex waters of El Rincon.
关键词： Absorption by phytoplankton,Bio-optical algorithms,Turbid coastal waters,Phytoplankton composition,Validation,MODIS-Aqua
更新于2025-09-23 15:22:29
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Underwater polarimetric imaging for visibility enhancement utilizing active unpolarized illumination
摘要： Underwater imaging is attractive but challenging. Images could be severely degraded by the particles in turbid water because of backscatter generation and signal light attenuation. In this paper, we focus on the scheme of underwater imaging and study the methods of visibility enhancement of turbid underwater images based on polarimetric imaging utilizing active unpolarized illumination. Compared with traditional polarimetric imaging using linearly polarized illumination, using unpolarized illumination ensures the polarization effect of the signal light could be neglected, no matter the depolarization degree of the object is high or low, which expands the application range of underwater polarimrteic imaging and makes the underwater polarimetric imaging scheme more reliable and robust. Experimentally, the visibility and the contrast of underwater images are enhanced effectively. In addition, it is demonstrated that our method is applicable for objects of different materials and different imaging distances in turbid water. The contrast of underwater images could be promoted at least 100%, meaning that this kind of technique can be potentially used in many underwater environments.
关键词： imaging through turbid media,polarimetric imaging,image enhancement
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing, China (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Research on Counting Algorithm of Residual Feeds in Aquaculture Based on Machine Vision
摘要： The waste of feed has always restricted the development of aquaculture. This paper presents an algorithm that can accurately obtain the residual information of feeds after a feeding event. With the purpose of applying the residual feed counting algorithm to the actual production, we focused on solving problems of counting feed pellets, such as turbid pond water, feed adhesion etc. We carry our experiments with different water turbidity levels and with feed adhesion, and some experiments have over 100 pellets. Experiments show that relative error can still be maintained at about 10% under the condition of turbid water and feed adhesion, which is much better than 20% obtained by other counting algorithm.
关键词： feed counting,turbid water,non-uniform illumination,feed identification,dark channel prior
更新于2025-09-23 15:21:21
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High-speed light source depth estimation using spatially-resolved diffuse imaging
摘要： We describe a system for high-speed depth estimation of a light source embedded in a scattering medium. A polynomial model estimates source depth from the spatially-resolved, diffuse reflectance profile measured with a fibre optic probe on the surface of a scattering medium. A dataset of Monte Carlo reflectance profiles is generated over a range of typical optical properties and the model is fit to the simulated reflectance at four detector locations. The model accounts for a source depth up to 15 mm. Cross-validation using the Monte Carlo dataset produced a root mean square error of 0.12 mm. Experimental reflectance data is acquired with the detector probe, which consists of four optical fibres mounted in a black acetal plastic disk. The optical fibres are coupled into avalanche photodiodes for high-speed acquisition of the reflectance profile. When applied to measurements from a tissue-mimicking phantom with an embedded light source, the polynomial model generates depth estimates within 2 mm of the true depth, up to a source depth of 15 mm.
关键词： source location,Monte Carlo simulation,tissue optics,turbid media,diffuse reflectance
更新于2025-09-19 17:15:36
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Experimental demonstration of imaging hidden objects in opaque liquid-based media by fusion of single-shot multiview polarized and unpolarized speckle images
摘要： Turbid water-based liquids are common scattering media within which imaging objects is challenging, since scattering particles of various origins and sizes may cause severe image degradation, resulting in poor object recovery and resolution. Therefore, counteracting the nontrivial effects of light scattering is a primary challenge, limiting the utility of optical imaging within liquid media. In this work, we sought to circumvent the optical degradation in turbid liquid media and to recover high-quality images of hidden objects by averaging polarized speckle images projected from several directions through a lens array. Inspired by astronomy imaging techniques, the averaging process utilized a Shift-and-Add (SAA) algorithm developed to reconstruct atmospherically-degraded solar images. Both linear and circular polarization strategies were then applied to further improve image reconstruction. Experiments were carried out using two targets, each having a distinct geometrical shape, embedded within turbid liquid media comprising a range of dilutions of commercially available cow’s milk in seawater. The media were irradiated with a polarized laser beam, after which multiple polarized speckled images were captured with a CCD camera. Offline, images were first shifted to a common center and then fused, using the SAA algorithm, to yield reconstructed images of each hidden object. Quantitative image quality metrics, including SNR, entropy, and sharpness were applied to evaluate quality of the reconstructed images. The reconstructed images obtained demonstrate successful adaptation of our methodology for the identification of hidden objects within turbid media. To the best of our knowledge, this is the first report to demonstrate successful imaging of hidden object images within turbid liquid media by averaging multiple polarized speckle projections.
关键词： Linear and circular polarization,Imaging through turbid water,Lens array,Multiple polarized speckle projections,Image processing
更新于2025-09-19 17:15:36
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A Mathematical Model of Laser Radiation Propagation in Seawater
摘要： Based on the well-known models of optical properties of a seawater layer in the spectral range of 530–550 nm, a mathematical model of the propagation of laser radiation is proposed. The mathematical model is obtained by solving radiative transfer equation for a narrow beam using a few-parameter approximation of the scattering indicatrix of the seawater layer. The model makes it possible to determine the spatial distribution of irradiance at a given distance from the laser radiation source by the known Secchi disk depth. The results of numerical experiments for water areas with known optical properties are given.
关键词： water inherent optical properties,turbid medium,optical radiation transfer,underwater vision system
更新于2025-09-16 10:30:52
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Fast 3D movement of a laser focusing spot behind scattering media by utilizing optical memory effect and optical conjugate planes
摘要： Controlling light propagation intentionally through turbid media such as ground glass or biological tissue has been demonstrated for many useful applications. Due to random scattering effect, one of the important goals is to draw a desired shape behind turbid media with a swift and precise method. Feedback wavefront shaping method which is known as a very effective approach to focus the light, is restricted by slow optimization process for obtaining multiple spots. Here we propose a technique to implement feedback wavefront shaping with optical memory effect and optical 4f system to speedy move focus spot and form shapes in 3D space behind scattering media. Starting with only one optimization process to achieve a focusing spot, the advantages of the optical configuration and full digital control allow us to move the focus spot with high quality at the speed of SLM frame rate. Multiple focusing spots can be achieved simultaneously by combining multiple phase patterns on a single SLM. By inheriting the phase patterns in the initial focusing process, we can enhance the intensity of the focusing spot at the edge of memory effect in with 50% reduction in optimization time. With a new focusing spot, we have two partially overlapped memory effect regions, expanding our 3D scanning range. With fast wavefront shaping devices, our proposed technique could potentially find appealing applications with biological tissues.
关键词： optical memory effect,biological tissues,turbid media,3D space,light propagation,feedback wavefront shaping
更新于2025-09-16 10:30:52