scholarly journals Characterizing Color Quality, Damage to Artwork, and Light Intensity of Multi-Primary LEDs for Museums

Heritage ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 188-197
Author(s):  
Dorukalp Durmus
Keyword(s):  
Energy Efficiency ◽  
Appearance Model ◽  
Light Sources ◽  
Great Flexibility ◽  
Oil Paintings ◽  
Damage Reduction ◽  
Output Variability ◽  
Color Quality ◽  
Trade Offs

Light causes damage when it is absorbed by sensitive artwork, such as oil paintings. However, light is needed to initiate vision and display artwork. The dilemma between visibility and damage, coupled with the inverse relationship between color quality and energy efficiency, poses a challenge for curators, conservators, and lighting designers in identifying optimal light sources. Multi-primary LEDs can provide great flexibility in terms of color quality, damage reduction, and energy efficiency for artwork illumination. However, there are no established metrics that quantify the output variability or highlight the trade-offs between different metrics. Here, various metrics related to museum lighting (damage, the color quality of paintings, illuminance, luminous efficacy of radiation) are analyzed using a voxelated 3-D volume. The continuous data in each dimension of the 3-D volume are converted to discrete data by identifying a significant minimum value (unit voxel). Resulting discretized 3-D volumes display the trade-offs between selected measures. It is possible to quantify the volume of the graph by summing unique voxels, which enables comparison of the performance of different light sources. The proposed representation model can be used for individual pigments or paintings with numerous pigments. The proposed method can be the foundation of a damage appearance model (DAM).

scholarly journals Application of different metrics for describing light color quality of white LED

2021 ◽  
Vol 13 (2) ◽  
pp. 31
Author(s):  
Robert Supronowicz ◽  
Jiajie Fan ◽  
Maciej Listowski ◽  
Adam Watras ◽  
Irena Fryc
Keyword(s):  
Thermal Quenching ◽  
Automated System ◽  
Light Sources ◽  
White Led ◽  
Viewing Angle ◽  
Color Quality ◽  
Trade Offs ◽  
Observer Model ◽  
Color Rendering

Using the example of the UV-excited Ca9KMg(PO4)7:1% Eu2+ phosphor, methods for characterizing the color quality of the light emitted by it at different operating temperatures are described. The effect of adopting two different colorimetric observers established by the International Commission on Illumination (i.e., the CIE 1931 observer with a viewing angle of two degrees and the CIE 2015 observer with a viewing angle of ten degrees) on the position of the chromaticity point of light emitted by phosphor is discussed. It was demonstrated that using the CIE 2015 photometric observer to determine the position of the chromaticity point, the tested phosphor is characterized by smaller changes in the color of emitted light as a function of operating temperature than when using the CIE 1931 observer. Full Text: PDF ReferencesR. Pązik et al., "Thermal quenching mechanisms of the Eu3+ luminescence in Ca9Al(PO4)7 obtained by citric route", Materials Research Bulletin, Vol. 48, I.2, 337 (2013). CrossRef I. Fryc, S. W. Brown, Y. Ohno, "A spectrally tunable LED sphere source enables accurate calibration of tristimulus colorimeters", Proc. SPIE Vol. 6158, 125 (2006) CrossRef Y. Ohno, "Practical Use and Calculation of CCT and Duv", LEUKOS, 10:1, 47-55, (2014). CrossRef D. Durmus, "Multi-objective optimization trade-offs for color rendition, energy efficiency, and circadian metrics", Proc. SPIE Vol. 11706, 117061J (2021) CrossRef I. Fryc, D. Czyzewski, " Dokładność pomiarowa spektroradiometrów typu CCD", Przeglad Elektrotechniczny R. 85(11), 276 (2009). DirectLink D. Czyzewski, "Zamienniki LED klasycznych żarówek", Przeglad Elektrotechniczny R. 88(11), 123 (2012). DirectLink J. Kusznier, W. Wojtkowski, "Spectral properties of smart LED lamps", Phot. Lett. Pol., 12(1), 16 (2020). CrossRef P. Hung, J. Y. Tsao, "Maximum White Luminous Efficacy of Radiation Versus Color Rendering Index and Color Temperature: Exact Results and a Useful Analytic Expression", Journ. of Display Techn., 9(6), 405 (2013). CrossRef Y. Asano, MD Fairchild, L. Blondé, "Individual Colorimetric Observer Model", PLOS ONE 11(2) e0145671 (2016). CrossRef Y. Wang, M. Wei, "Preference among light sources with different Duv but similar colour rendition: A pilot study", Lighting Res. & Tech., 50(7), 1013 (2018). CrossRef K. A. G. Smet, "Tutorial: The LuxPy Python Toolbox for Lighting and Color Science", LEUKOS, 16:3, 179 (2020). CrossRef D. Petrisor, C. D. Galatanu, C. Haba, L. Breniuc "Color Quality Measurements of LED Light Sources Using Image Processing", EEEIC/I&CPS Europe, 1, (2019) CrossRef ANSI C78.377:2017 DirectLink I. Fryc, T. Dimitrova-Grekow, "An Automated System for Evaluation of the Quality of Light Sources", 2016 IEEE (Lumen V4), 1 (2016). CrossRef Y. Ohno, "Spectral design considerations for white LED color rendering", Optical Engineering 44(11), 111302 (2005). CrossRef E. Purwanto, P. Dupuis, L. Canale, N. I. Sinisuka, G. Zissis, "Aging study of remote luminophore at ambient temperature", EEEIC/I&CPS Europe, 1 (2019). CrossRef J. Fan, Y. Li, I. Fryc, C. Qian, X. Fan, G. Zhang, "Machine-Learning Assisted Prediction of Spectral Power Distribution for Full-Spectrum White Light-Emitting Diode", IEEE Photonics Journal, 12(1), 1 (2020). CrossRef D. Mozyrska, M. Wyrwas, I. Fryc, "Wyznaczanie parametrów kolorymetrycznych LEDa w pełnym zakresie temperatur pracy", Przeglad Elektrotechniczny R. 93(4a), 232 (2012). CrossRef I. Fryc, "Analiza właściwości spektralnych LEDów z zależności od temperatury i natężenia ich prądu pracy", Przeglad Elektrotechniczny R. 86(10), 187 (2010). DirectLink I. Fryc, "Pomiary wybranych parametrów świetlno-optycznych LEDów według zaleceń Międzynarodowej Komisji Oświetleniowej CIE 127:2007", Przeglad Elektrotechniczny R. 85(11), 317 (2009). DirectLink A. David et al., "Development of the IES method for evaluating the color rendition of light sources", Opt. Express 23, 15888 (2015). CrossRef S Jost-Boissard, P Avouac, M Fontoynont, "Assessing the colour quality of LED sources: Naturalness, attractiveness, colourfulness and colour difference", Lighting Research & Technology, 47(7): 769 (2015). CrossRef J. Kowalska, "Określanie jakości oddawania barw źródeł światła parametrami przedstawionymi w zaleceniach IES TM-30-15 i CIE 013.3-1995", Przeglad Elektrotechniczny R. 93(6), 50 (2017). DirectLink J. Kowalska, I. Fryc, "Jakość oddawania barw współczesnych lamp fluorescencyjnych określona zdefiniowanym przez CIE wskaźnikiem wierności barwy oraz wskaźnikiem oddawania barw", Przeglad Elektrotechniczny R. 95(7), 94 (2019). DirectLink CIE 170-2:2015 DirectLink

Correlated color temperature: Use and limitations

2021 ◽  
pp. 147715352110343
Author(s):  
D Durmus
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Ease Of Use ◽  
Chromatic Adaptation ◽  
Color Temperature ◽  
Light Sources ◽  
One Dimensional ◽  
Spectral Power Distribution ◽  
Color Quality

Correlated color temperature (CCT) is a one-dimensional metric that aims to quantify the perceived visual quality of nominal white light sources. It is often used as a proxy for the color quality of light sources due to its ease of use. However, CCT lacks the accuracy in communicating color information for research purposes. Two light sources with identical CCTs can appear perceptually different, and these differences are not estimated by CCT due to the loss of information caused by reducing spectral power distribution of light sources into a one-dimensional metric. Using supplemental metrics in addition to CCT, providing the absolute spectral power distribution of light sources in graphical and tabular form, and documenting and accounting for potential confounding factors, such as chromatic adaptation, can increase the validity of research results, improve the repeatability of studies, and help address replication concerns.

Color Quality of Semiconductor and Conventional Light Sources

2017 ◽  
Author(s):  
Tran Quoc Khanh ◽  
Peter Bodrogi ◽  
Trinh Quang Vinh
Keyword(s):  
Light Sources ◽  
Color Quality

Towards Universal Evaluation Method for Color Quality of Light Sources

2015 ◽  
Vol 35 (8) ◽  
pp. 0833001
Author(s):  
章夫正 Zhang Fuzheng ◽  
徐海松 Xu Haisong ◽  
吴晓玟 Wu Xiaomin ◽  
蔡建奇 Cai Jianqi
Keyword(s):  
Evaluation Method ◽  
Light Sources ◽  
Color Quality

Toward a unified model for predicting color quality of light sources

2017 ◽  
Vol 56 (29) ◽  
pp. 8186 ◽  
Author(s):  
Fuzheng Zhang ◽  
Haisong Xu ◽  
Heng Feng
Keyword(s):  
Unified Model ◽  
Light Sources ◽  
Color Quality

scholarly journals Assessment of Lighting Uniformity as a Factor of Energy Efficiency in Greenhouse Horticulture

2021 ◽  
Vol 31 (3) ◽  
pp. 470-486
Author(s):  
Sergey A. Rakutko ◽  
Elena N. Rakutko
Keyword(s):  
Energy Efficiency ◽  
Subject Area ◽  
Efficiency Factor ◽  
Light Distribution ◽  
Light Sources ◽  
Increase Energy Efficiency ◽  
Greenhouse Horticulture ◽  
Lighting Systems ◽  
The Impact

Introduction. Greenhouse lighting systems are an integral part of the system for growing plants in cultivation facilities with an artificial microclimate. The uniformity of light distribution over the growing area is important to increase energy efficiency and improve plant quality, among other requirements. The aim of the work is to consider the mathematical apparatus for describing the distribution of light over the surface and to justify the choice of ways to characterize the degree of lighting uniformity. Materials and Methods. The basic concepts of the subject area such as lighting, lighting body, horizontal lighting curve, luminous intensity curve are considered in terms of theoretical photometry. To assess the energy and ecological friendliness of the greenhouse horticulture, the lighting efficiency factor was used. Various methods for determining the average lighting value are presented. The formulas for the uniformity coefficients are presented. Experimental verification was carried out on a horizontal plane simulating a surface for growing plants. A luminary with a round-symmetric light distribution was used. Results. It has been found that the lighting values calculated by the proposed method at various points of the illuminated surface correspond to the experimentally obtained values. It has been shown that the coefficient taking into account the pattern of lighting distribution over all points of the surface carries a lot of information about the uniformity. A frequency graph for the lighting distribution value has been constructed and its practical applicability has been substantiated. The relationship between the lighting efficiency and uniformity of the generated lighting has been revealed. With reduced suspension height of the luminary, it is possible to increase significantly the lighting efficiency factor, however, the lighting uniformity deteriorates sharply. Discussion and Conclusion. There is proposed a method for assessing the energy efficiency by the lighting efficiency factor, which determines the proportion of the useful lighting falling on the surface in the total lighting generated by light sources. It is suggested that this indicator can characterize the ecological quality of photoculture, since it has been established its relationship with the uniformity of the created lighting, the impact of which on photoculture is described in the literature.

scholarly journals Energy efficiency and color quality limits in artificial light sources emulating natural illumination

2014 ◽  
Vol 22 (S7) ◽  
pp. A1659 ◽  
Author(s):  
Wim Hertog ◽  
Aleix Llenas ◽  
Jesús M. Quintero ◽  
Charles E. Hunt ◽  
Josep Carreras
Keyword(s):  
Energy Efficiency ◽  
Artificial Light ◽  
Light Sources ◽  
Natural Illumination ◽  
Color Quality

A Political Economy Model of a Research University

2009 ◽  
pp. 132-143
Author(s):  
K. Sonin ◽  
I. Khovanskaya
Keyword(s):  
Organizational Structure ◽  
Information Structure ◽  
Research University ◽  
Hiring Decisions ◽  
Voting Rules ◽  
Economy Model ◽  
Trade Offs ◽  
Political Economic ◽  
Optimal Incentives

Hiring decisions are typically made by committees members of which have different capacity to estimate the quality of candidates. Organizational structure and voting rules in the committees determine the incentives and strategies of applicants; thus, construction of a modern university requires a political structure that provides committee members and applicants with optimal incentives. The existing political-economic model of informative voting typically lacks any degree of variance in the organizational structure, while political-economic models of organization typically assume a parsimonious information structure. In this paper, we propose a simple framework to analyze trade-offs in optimal subdivision of universities into departments and subdepartments, and allocation of political power.

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