Papers by Keyword: Reflectance

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Authors: Qiao Chen, Li Jie Wang, Stephen Westland
Abstract: Spectral images contain a large volume of data and the development of multispectral imaging systems places considerable demands on computer hardware and software compared with standard three-component or trichromatic image storage and processing. This study is concerned with lossy compression techniques for spectral images since many color images are intended for display for human perception and it is well established that images contain redundancies (in terms of their color, spatial and temporal properties) that can be removed without any loss in image quality. The lossy compression technique that is considered in this work is a low-dimensional linear model of spectral reflectance, with which the basis function are derived from color matching functions that are correlated with human visual system.
Authors: Qiao Chen, Li Jie Wang, Stephen Westland
Abstract: Spectral images contain a large volume of data and can be efficiently compressed by low dimensional linear models. However, there is a trade-off between the accuracy of spectral and colorimetric representation. When a spectral image is reproduced by a low-dimensional linear model, spectral error and color difference are contrary to each other and minimizing the colour error is by no means equivalent to minimizing the spectral error. Although one aim of a spectral-image file format is to preserve and represent the spectral information, most users are likely to reproduce a spectral image on a trichromatic image-reproduction system and therefore it is important that the spectral information is not preserved at the expense of colorimetric accuracy. In this study a method for spectral encoding that provides an efficient representation of the spectral information whilst perfectly preserving the colorimetric information is analysed. The lossy compression technique that is considered in this work is based on a low-dimensional linear model of spectral reflectance, with the first three basis functions represent color information and the additional basis functions are metameric blacks which preserve spectral information.
Authors: Qiao Chen, Li Jie Wang, Stephen Westland
Abstract: Recent computational models of color vision demonstrate that it is possible to achieve exact color constancy over a limited range of lights and surfaces described by a low-dimensional linear model. For smooth reflectance spectra the different spectral bands have a significant degree of correlation. Any spectral reflectance distribution can be approximated to a specified degree of accuracy as a weighted sum of basis functions. Reflectance spectra of hyperspectral images of the natural scenes are supposed to represent the real world better than any certain classes of natural and man-made spectral reflectance data sets such as rocks, leaves, Munsell chips, etc. The characteristics of the spectra will be important to understand the spectral properties of the object reflectance and the representation of spectral images by linear models. In this study sets of hyperspectral images have been analyzed by principal-component analysis (PCA) method for spectral encoding.
Authors: Zaliman Sauli, Vithyacharan Retnasamy, Ong Tee Say
Abstract: The Lambda 950 spectrometers are designed to investigate and examine surface coating on test specimen by using the light source. The objective of this research is to investigate the factors that affect the surface roughness and reflectance after different parameter of Reactive Ion Etching (RIE) process. There are four parameters to control the RIE process which is temperature, vacuum, RF (Radio Frequency) power and gas flow. The parameters in this research are using a Full Factorial Experimentation technique, the Design of Experiment (DOE). The AFM (Atomic Force Microscope) and Lambda 950 spectrometer are used to analyse the surface roughness and light reflectance of the specimen. The result showed all four parameters of RIE were give effect on surface roughness and surface reflectance. The parameter of gas flow is the most influence factor for surface roughness and surface reflectance compared to other parameters in this work.
Authors: Luís Matias, Luís Gonçalves, Alexandra Costa, Carlos Pina Santos
Abstract: High reflective paints (cool paints) can reduce solar heat gains, improving thermal comfort and energy efficiency in buildings in summer period. To evaluate the thermal performance of different reflective paints applied in façades (over ETICS like solution) a research study is being developed at LNEC using full-scale test cells built in LNEC’s campus.For this purpose, non-destructive infrared thermography method is being used. This method allows knowing the temperature distribution on façades by measuring infrared radiation emitted from its surfaces. Thermocouples placed on wall outside surfaces support thermographic diagnosis.Optical properties of cool paints (reflectance and emittance) used in this research study were achieved by additional laboratory tests.Comparative analysis between thermal performance of a white cool paint and a white conventional paint is presented in this paper. This research study also shows the potential of infrared thermography in the assessment of thermal performance of cool paints.
Authors: Jozef Hraška, Peter Hartman
Abstract: The study presented in this article aims to evaluate in which extent the interior colour surfaces affects human circadian stimulus. Experimental measurements in model rooms were evaluated by methods presented in studies by Rea et al. [1-3]. Even by high levels of daylight illuminances the colour of interior surfaces influences circadian stimulus, but this effect is not significant. Diminishing of circadian efficacy increases with application of dark blue-deficient colours of interior surfaces and by low intensity of daylight.
Authors: Wan Noni Afida Ab Manan, Arnis Asmat, Noordin Ahmad
Abstract: Visibility, aerosol optical thickness and water vapor are important atmospheric parameters that vary in space and time. Using radiative transfer algorithm to derive surface reflectance from imaging these values would be critical to be assigned. This study will investigate the optimum range of visibility and aerosol loading in Malaysia deriving from atmospheric model. Urban atmospheric model was performed into two major cities in Malaysia to represent for ideal tropical climate. The study found that the farthest visibility range at 50km,the aerosol loading was low and the shortest range at 10 km was contain high aerosol loading. Relatively, aerosol loading estimation is higher at close-shore city (Penang) than inland city (Kuala Lumpur).
Authors: K. Makita, H. Inaba, Hiroshi Sakai
Authors: Vitaly V. Neshchimenko, Chun Dong Li, Mikhail M. Mikhailov, Andrei Dudin
Abstract: The effect of protons exposure on the diffuse reflectance spectra of the zinc oxide with different shape particles has been investigated. Particles were micro-, nanocrystals, star and flower shape particles. The synthesis of the particles was carried out by the hydrothermal method using zinc acetate chemicals. The surface morphology, surface area and crystal structure of the particles have been investigated. Evaluating the changes in spectral reflectance it was found that the radiation stability of the micro particles is higher than the radiation stability of the other nanostructured particles. The high stability of the micro particles optical properties is due to the effect of low accumulation of radiation-induced defects.
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