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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - The Uncertainty of Measurement of Spectroradiometric System with Double Monochromator
摘要： This article has task to inform a reader about uncertainties of measurement of spectroradiometric systems with double monochromator. Uncertainty of measurement is very important for all photometric measurements and calculations. Spectroradiometric system’s uncertainty is dependent on wavelength and is difficult to estimate uncertainty of measurement for photometric parameters calculated from measured spectrum. In the first part of this article there is theory necessary for understanding uncertainty analyses and description of construction of spectroradiometric system with double monochromator. In the second part there is practical uncertainty analysis of double monochromator in light laboratory and its results.
关键词： spectral irradiance,correlated color temperature,double monochromator,color rendering index,Uncertainty of measurement
更新于2025-09-23 15:21:21
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Upconversion luminescence properties of Y2O3: Yb3+/Er3+/Tm3+ nanocrystal doped PMMA nanocomposites
摘要： Y2O3 nanocrystals triply doped with Yb3+, Er3+, Tm3+ ions were synthesized via alginic acid-assisted gelation using thermal decomposition method and annealed at 800 °C for 24 h. Nanopowders were embedded into PMMA matrix via free-radical polymerization in an ultrasonic bath. X-ray diffraction and transmission electron microscopy measurements have shown that the crystal grain sizes decreased significantly with the narrow size distributions of the nanocrystals in PMMA matrix. A diode laser at 975 nm was used to measure the upconversion luminescence of the annealed nanopowders and those embedded in PMMA between the 400–850 nm wavelength region. The Er3+ concentration and the excitation power density dependencies of the relative intensities for red, green and blue upconversion luminescence in the nanopowder and PMMA nanocomposites are found to be different. The measured CIE-1931 color coordinates of the upconversion luminescence in PMMA nanocomposites show appreciable color stability under different excitation power densities, which is required for potential applications in the field of photonics.
关键词： Color Tunable Emission,Upconversion Luminescence,Polymer nanocomposites,Color Stability,Polymethyl methacrylate (PMMA)
更新于2025-09-23 15:21:21
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Tuning phosphors for better white light
摘要： Light-emitting diodes (LEDs) that produce white light are about to take over the lighting world. The U.S. market share of these super-long-lasting, cool-to-the-touch lights, which use less than a quarter of the energy of conventional incandescent bulbs, sits around 10%. Industry watchers predict that number will exceed 80% by 2030, reducing power consumption in the U.S. by 40%. Chemists are taking a leading role in this technology, which underpins general lighting and electronic displays, by customizing the emission spectrum, stability, and other properties of inorganic phosphors in the LEDs that help produce finely tuned white light.
关键词： energy efficiency,inorganic phosphors,color rendering index,LEDs,white light
更新于2025-09-23 15:21:21
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Generalized Content-Preserving Warp: Direct Photometric Alignment beyond Color Consistency
摘要： Motion estimation is vital in many computer vision applications. Most existing methods require high quality and large quantity of feature correspondence, and may fail for images with few textures. In this paper, a photometric alignment method is proposed to obtain better motion estimation result. Since the adopted photometric constraints are usually limited to required illumination or color consistency assumption, a new Generalized Content-Preserving Warp (GCPW) framework therefore is designed to perform photometric alignment beyond color consistency. Similar to conventional Content-Preserving Warp (CPW), GCPW is also a mesh-based framework, but it extends CPW by appending a local color transformation model for every mesh quad, which expresses the color transformation from a source image to a target image within the quad. Motion-related mesh vertexes and color-related mapping parameters are optimized jointly in GCPW to get more robust motion estimation result. Evaluation of tens of videos reveals that the proposed method achieves more accurate motion estimation results. More importantly, it is robust to significant color variation. Besides, this paper explores the performance of GCPW in two popular computer vision applications: image stitching and video stabilization. Experimental results demonstrate GCPW's effectiveness in dealing with typical challenging scenes for these two applications.
关键词： Color Difference,Video Stabilization,Photometric Constraint,Image Stitching,Motion Estimation
更新于2025-09-23 15:21:21
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Shallow Water Ocean Color Observations Inversion Using Particle Swarm Optimization and Genetic Algorithm
摘要： In this work, Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) optimization techniques are used to retrieve water column inherent optical properties (IOPs), bottom reflectance and geometric depth from a simulated hyperspectral dataset. The synthetic dataset (N=6000) is created using two different bottom types (Sand and seagrass), three levels of depth, 20 concentrations of Chlorophyll – a (Chl-a) with a wide range of modelled IOP variations resembling natural clear and optically complex waters. Results indicate that PSO and GA showed similar retrieval results in IOPs. Bottom reflectance values from PSO are near to input bottom substrate values compared to GA. In case of Geometric depth also, average depth value retrieved by PSO are better than GA retrieved. In terms of processing time, PSO exhibited higher computational efficiency than GA by five times. Further studies can use PSO to process Hyperspectral remote sensing Imagery in shallow waters.
关键词： PSO,Shallow waters,Ocean color inversion,Optimization,GA
更新于2025-09-23 15:21:21
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Use and Analysis of Color Models in Image Processing
摘要： The use of color image processing is divided by two factors. First color is used in object identification and simplifies extraction from a scene and color is powerful descriptor. Second, humans can use thousands of color shades and intensities. Color Image Processing is divided into two areas full color and pseudo-color processing. In this processing various color models are used that are based on color recognition, color components etc. A few papers on various applications such as lane detection, face detection, fruit quality evaluation etc based on these color models have been published. A survey on widely used models RGB, HSI, HSV, RGI, etc. is represented in this paper.
关键词： Color models,HIS,HSV,RGI,RGB,Image processing
更新于2025-09-23 15:21:21
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[IEEE 2018 IEEE Southwest Symposium on Image Analysis and Interpretation (SSIAI) - Las Vegas, NV (2018.4.8-2018.4.10)] 2018 IEEE Southwest Symposium on Image Analysis and Interpretation (SSIAI) - Estimating Plant Centers Using A Deep Binary Classifier
摘要： Phenotyping is the process of estimating the physical and chemical properties of a plant. Traditional phenotyping is labor intensive and time consuming. These measurements can be obtained faster by collecting aerial images with an Unmanned Aerial Vehicle (UAV) and analyzing them using modern image analysis technologies. We propose a method to estimate plant centers by classifying each pixel as a plant center or not a plant center. We then label the center of each cluster as the plant location. We studied the performance of our method on two datasets. We achieved 84% precision and 90% recall on one dataset consisting of early stage plants and 62% precision and 77% recall on another dataset consisting of later stage plants.
关键词： Color Image Processing,Plant Phenotyping,CNN,Machine Learning
更新于2025-09-23 15:21:21
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[IEEE 2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE - Barcelona, Spain (2019.9.2-2019.9.6)] 2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE - (a??Oops! Had the silly thing in reversea??)a??Optical injection attacks in through LED status indicators
摘要： Color breakup is a lethal issue to conventional field-sequential-color LCDs. Several methods have been proposed to solve this problem. However, these solutions are either more than 180 Hz—the currently used LC mode is not sufficiently fast for this field rate—or they degrade the image quality while using a field rate of 120 Hz. To overcome these limitations, a 120 Hz Stencil Local Primary Desaturation, Stencil-LPD, is presented in this work. The 120 Hz Stencil-LPD method provides reduced but sufficient saturated backlight color to precisely present an image with less color distortion or color breakup. After optimizing a number of backlight segments, the experimental results demonstrate that the image fidelity is significantly improved and color breakup is greatly suppressed compared to the existing methods.
关键词： stencil,local-primary-desaturation,field-sequential-color,LPD,FSC,color breakup
更新于2025-09-23 15:21:01
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - A Color Compensation Method for Three Primary-color LED Light Sources
摘要： The three primary-color LED light source modules produce a color within the gamut space by the Pulse-Width-Modulation (PWM) duty cycle. In a host control multiple LED module system, due to the specificity of the three primary-color LED light sources, different light source modules cannot generate the same target color coordinates according to the same set of duty ratio data, thereby causing a color inconsistency in each light source. This paper proposes an algorithm for personalizing the Red-Green-Blue (RGB) values by using the three primary-color coordinates obtained by feedbacks. Through extensive experiments, the algorithm can effectively reduce the color difference produced by different LED lamp beads. The algorithm has a small amount of calculation and can be easily implemented in practical devices.
关键词： LED light sources,color consistency,Color compensation,RGB values,PWM
更新于2025-09-23 15:21:01
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Color image encryption based on enhanced optical interference with different diffraction distances and linear phase color-blend
摘要： We develop a novel method to encrypt a color image by combining enhanced optical interference with phase retrieval algorithm (PRA) and linear phase color-blend (LPCB). In this method, the original color image is encoded into three phase only masks (POMs) with different Fresnel diffraction distances and one fixed random phase mask (RPM). For the decryption in an optical interference system, the three individual POMs are placed in the red, green and blue channels, respectively, and the RPM is placed in the public channel. Only if the right POMs and RPM are fixed their positions properly, one could achieve the expected information. Compared with traditional interference-based color image method, our method eliminates the silhouette problem fully. LPCB is also introduced to modulate the phase value of each pixel of the three POMs to further enhance the security. Numerical simulation results are presented to illustrate the feasibility and effectiveness of the proposed scheme.
关键词： Optical interference,Linear phase color-blend,Phase retrieval algorithm,Color image encryption
更新于2025-09-23 15:21:01