- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Geometry-aware metropolis light transport
摘要： Markov chain Monte Carlo (MCMC) rendering utilizes a sequence of correlated path samples which is obtained by iteratively mutating the current state to the next. The efficiency of MCMC rendering depends on how well the mutation strategy is designed to adapt to the local structure of the state space. We present a novel MCMC rendering method that automatically adapts the step sizes of the mutations to the geometry of the rendered scene. Our geometry-aware path space perturbation largely avoids tentative samples with zero contribution due to occlusion. Our method limits the mutation step size by estimating the maximum opening angle of a cone, centered around a segment of a light transport path, where no geometry obstructs visibility. This geometry-aware mutation increases the acceptance rates, while not degrading the sampling quality. As this cone estimation introduces a considerable overhead if done naively, to make our approach efficient, we discuss and analyze fast approximate methods for cone angle estimation which utilize the acceleration structure already present for the ray-geometry intersection. Our new approach, integrated into the framework of Metropolis light transport, can achieve results with lower error and less artifact in equal time compared to current path space mutation techniques.
关键词： global illumination,Markov chain Monte Carlo light transport
更新于2025-09-23 15:23:52
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A detail preserving variational model for image Retinex
摘要： In this paper, we propose a detail preserving variational model for Retinex to simultaneously estimate the illumination and the reflectance from an observed image. Most previous models use the log-transform as pretreatment which results in loss of details in reflectance. From this observation, a detail preserving variational method is proposed for better decomposition. Different from the log-transform based models, the proposed model performs the decomposition directly in the image domain. Mathematically, we prove the existence of a solution for the proposed model. Numerically, we derive an efficient iterative algorithm by utilizing alternating direction method of multipliers (ADMM) method. Experimental results demonstrate the effectiveness of the proposed method. Compared with other closely related Retinex methods, the proposed method achieves competitive results on both subjective and objective assessments.
关键词： Reflectance,Retinex,Illumination,Variational model,Image decomposition
更新于2025-09-23 15:23:52
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Illumination discrimination in the absence of a fixed surface-reflectance layout
摘要： Previous studies have shown that humans can discriminate spectral changes in illumination and that this sensitivity depends both on the chromatic direction of the illumination change and on the ensemble of surfaces in the scene. These studies, however, always used stimulus scenes with a fixed surface-reflectance layout. Here we compared illumination discrimination for scenes in which the surface reflectance layout remains fixed (fixed-surfaces condition) to those in which surface reflectances were shuffled randomly across scenes, but with the mean scene reflectance held approximately constant (shuffled-surfaces condition). Illumination discrimination thresholds in the fixed-surfaces condition were commensurate with previous reports. Thresholds in the shuffled-surfaces condition, however, were considerably elevated. Nonetheless, performance in the shuffled-surfaces condition exceeded that attainable through random guessing. Analysis of eye fixations revealed that in the fixed-surfaces condition, low illumination discrimination thresholds (across observers) were predicted by low overall fixation spread and high consistency of fixation location and fixated surface reflectances across trial intervals. Performance in the shuffled-surfaces condition was not systematically related to any of the eye-fixation characteristics we examined for that condition, but was correlated with performance in the fixed-surfaces condition.
关键词： illumination perception,color vision,eye fixations,chromatic illumination discrimination
更新于2025-09-23 15:22:29
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Single Image Defogging Based on Illumination Decomposition for Visual Maritime Surveillance
摘要： Single image fog removal is important for surveillance applications and many defogging methods have been proposed, recently. Due to the adverse atmospheric conditions, the scattering properties of foggy images depend on not only the depth information of scene, but also the atmospheric aerosol model, which has more prominent influence on illumination in a fog scene than that in a haze scene. However, recent defogging methods confuse haze and fog, and they fail to consider fully about the scattering properties. Thus, these methods are not sufficient to remove fog effects, especially for images in maritime surveillance. Therefore, this paper proposes a single image defogging method for visual maritime surveillance. Firstly, a comprehensive scattering model is proposed to formulate a fog image in the glow-shaped environmental illumination. Then, an illumination decomposition algorithm is proposed to eliminate the glow effect on the airlight radiance and recover a fog layer, in which objects at the infinite distance have uniform luminance. Secondly, a transmission-map estimation based on the non-local haze-lines prior is utilized to constrain the transmission map into a reasonable range for the input fog image. Finally, the proposed illumination compensation algorithm enables the defogging image to preserve the natural illumination information of the input image. In addition, a fog image dataset is established for visual maritime surveillance. The experimental results based on the established dataset demonstrate that the proposed method can outperform the state-of-the-art methods in terms of both the subjective and objective evaluation criteria. Moreover, the proposed method can effectively remove fog and maintain naturalness for fog images.
关键词： Illumination Decomposition,Haze-Lines Prior,Image Defogging,Atmospheric Aerosol Model,Visual Maritime Surveillance
更新于2025-09-23 15:22:29
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[IEEE 2018 UKSim-AMSS 20th International Conference on Computer Modelling and Simulation (UKSim) - Cambridge, United Kingdom (2018.3.27-2018.3.29)] 2018 UKSim-AMSS 20th International Conference on Computer Modelling and Simulation (UKSim) - Simulating Optical Behavior of Nano Dimensional InAlAs/InGaAs HEMT for IoT Applications
摘要： This paper presents a comprehensive analysis of the photogeneration effect in high electron mobility transistors (HEMTs) under optical illumination. The study focuses on the impact of photogenerated carriers on the device performance, particularly in the context of simulation and modeling. The research utilizes an interpreter-based simulation approach to accurately model the photogeneration process and its effects on the electrical characteristics of HEMTs. The results demonstrate significant changes in the device behavior under illumination, highlighting the importance of considering optical effects in the design and optimization of HEMT-based optoelectronic devices. The findings provide valuable insights into the photoresponse of HEMTs and contribute to the advancement of optoelectronic simulation techniques.
关键词： simulation,Photogeneration,interpreter,HEMT,optical illumination
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference of the Biometrics Special Interest Group (BIOSIG) - Darmstadt (2018.9.26-2018.9.28)] 2018 International Conference of the Biometrics Special Interest Group (BIOSIG) - A benchmark database of visible and thermal paired face images across multiple variations
摘要： Although visible face recognition systems have grown as a major area of research, they are still facing serious challenges when operating in uncontrolled environments. In attempt to overcome these limitations, thermal imagery has been investigated as a promising direction to extend face recognition technology. However, the reduced number of databases acquired in thermal spectrum limits its exploration. In this paper, we introduce a database of face images acquired simultaneously in visible and thermal spectra under various variations: illumination, expression, pose and occlusion. Then, we present a comparative study of face recognition performances on both modalities against each variation and the impact of bimodal fusion. We prove that thermal spectrum rivals with the visible spectrum not only in the presence of illumination changes, but also in case of expression and poses changes.
关键词： visible spectrum,thermal spectrum,pose,score-level fusion,sensor-level fusion,occlusion,expression,illumination,face database
更新于2025-09-23 15:22:29
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Trap-assisted enhanced bias illumination stability of oxide thin film transistor by praseodymium doping
摘要： Praseodymium-doped indium zinc oxide (PrIZO) have been employed as the channel layer of thin film transistors (TFTs). The TFTs with Pr doping exhibited a remarkable suppression of the light induced instability. A negligible photo-response and remarkable enhancement in negative gate bias stress under illumination (NBIS) were achieved in the PrIZO-TFTs. Meanwhile, the PrIZO-TFTs showed reasonable characteristics with a high field effect mobility of 26.3 cm2/Vs, SS value of 0.28 V/decade, and Ion/Ioff ratio of 108. X-ray photoelectron spectroscopy (XPS), microwave photoconductivity decay (Micro-PCD) and photoluminescence spectra (PL) were employed to analyze the effects of the Pr concentrations on the performance of PrIZO-TFTs. We disclosed that acceptor-like trap states induced by Pr ions might lead to the suppression of photo-induced carrier in conduction band, which is a new strategy for improving illumination stability of amorphous oxide semiconductors. Finally, a prototype of fully transparent AMOLED display was successfully fabricated to demonstrate the potential of Pr-doping TFTs applied in transparent devices.
关键词： Praseodymium doping,negative bias illumination stress,metal oxide,thin film transistor,photo-response
更新于2025-09-23 15:22:29
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[IEEE OCEANS 2018 MTS/IEEE Charleston - Charleston, SC, USA (2018.10.22-2018.10.25)] OCEANS 2018 MTS/IEEE Charleston - Dynamic beam shaping exploiting orbital angular momentum for underwater structured light illumination
摘要： This work demonstrates dynamic optical beam generation using two different approaches: a Mach-Zehnder interferometer to generate three coherently coupled orbital angular momentum modes and a HOBBIT (high-order Bessel beams integrated in time) system which switches between spatial modes. By expanding the number of coherently coupled modes, a broad range of structured light patterns can be spatially and temporally controlled for structured illumination in underwater imaging applications.
关键词： underwater,orbital angular momentum,interference,structured illumination,coherent
更新于2025-09-23 15:22:29
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A New Invariant to Illumination Feature Descriptor for Pattern Recognition
摘要： A new descriptor for describing features in gray-scale images that is invariant to nonuniform illumination is proposed. The suggested method for the feature descriptor design is based on a local energy model which is a biologically plausible model of the visual system. The algorithm for feature detection and construction of the descriptor uses the scale-space monogenic signal framework and a modified algorithm for calculation of the histogram of oriented gradients based on the phase congruence of the signals. The results of computer simulation show that the proposed descriptor provides excellent detection and matching of features at nonuniform illumination, noise, and minor geometric distortions in comparison with known descriptors.
关键词： phase congruency,feature descriptor,nonuniform illumination,monogenic signal,histogram of oriented gradients
更新于2025-09-23 15:22:29
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Highlight shapes and perception of gloss for real and photographed objects
摘要： Gloss perception strongly depends on the three-dimensional shape and the illumination of the object under consideration. In this study we investigated the influence of the spatial structure of the illumination on gloss perception. A diffuse light box in combination with differently shaped masks was used to produce a set of six simple and complex highlight shapes. The geometry of the simple highlight shapes was inspired by conventional artistic practice (e.g., ring flash for photography, window shape for painting and disk or square for cartoons). In the box we placed spherical stimuli that were painted in six degrees of glossiness. This resulted in a stimulus set of six highlight shapes and six gloss levels, a total of 36 stimuli. We performed three experiments of which two took place using digital photographs on a computer monitor and one with the real spheres in the light box. The observers had to perform a comparison task in which they chose which of two stimuli was glossiest and a rating task in which they rated the glossiness. The results show that, perhaps surprisingly, more complex highlight shapes were perceived to produce a less glossy appearance than simple highlight shapes such as a disk or square. These findings were confirmed for both viewing conditions, on a computer display and in a real setting. The results show that variations in the spatial structure of ''rather simple'' illumination of the ''extended source'' type highlight influences perceived glossiness.
关键词： shape,gloss,natural scenes,highlight,illumination
更新于2025-09-23 15:22:29