COLOUR FIDELITY AND ILLUMINANCE TRADE-OFF: TESTING LIGHTING VALUES

2021 ◽  
Author(s):  
J.A. Veitch ◽  
L.A. Whitehead
Keyword(s):  
Energy Efficiency ◽  
Light Source ◽  
Reflectance Spectra ◽  
Source Spectrum ◽  
Light Sources ◽  
Trade Off ◽  
Luminous Efficacy ◽  
Reading Task ◽  
Colour Appearance ◽  
Effect Of Light

The higher the colour fidelity of a light source, the lower its luminous efficacy of radiation because the light source spectrum must deviate from V(λ) to deliver the higher fidelity. Two experiments probed the trade-off between energy efficiency and colour quality. Experiment 1 required participants to simultaneously view pairs of light sources differing in colour fidelity, at either a higher (346 lx) or lower (277 lx) illuminance. Participants performed a timed reading task and judged the colour appearance of the pair. There were no effects of illuminance, but larger colour fidelity differences between the light sources in the pair correlated with lower appearance judgements. Experiment 2 simulated the effect of light sources on defined reflectance spectra. The results showed that improvements of colour fidelity above what is often considered satisfactory can yield more satisfying illumination while using the same amount of power.

scholarly journals Towards the Optimum Light Source Spectrum

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Andrew Chalmers ◽  
Snjezana Soltic
Keyword(s):  
Light Source ◽  
Large Scale ◽  
Source Spectrum ◽  
Light Sources ◽  
Luminous Efficacy ◽  
Light Emitting ◽  
Spectral Bands ◽  
Good Energy ◽  
Lighting Systems ◽  
Colour Rendering

This paper is concerned with designing light source spectra for optimum luminous efficacy and colour rendering. We demonstrate that it is possible to design light sources that can provide both good colour rendering and high luminous efficacy by combining the outputs of a number of narrowband spectral constituents. Also, the achievable results depend on the numbers and wavelengths of the different spectral bands utilized in the mixture. Practical realization of these concepts has been demonstrated in this pilot study which combines a number of simulations with tests using real LEDs (light emitting diodes). Such sources are capable of providing highly efficient lighting systems with good energy conservation potential. Further research is underway to investigate the practicalities of our proposals in relation to large-scale light source production.

scholarly journals Influence of a Light Source Installed in a Luminaire of Opal Sphere Type on the Effect of Light Pollution

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 306 ◽  
Author(s):  
Przemyslaw Tabaka ◽  
Pawel Rozga
Keyword(s):  
Light Source ◽  
Spectral Distribution ◽  
Spectral Characteristics ◽  
Measurement Data ◽  
Luminous Flux ◽  
Light Pollution ◽  
Light Sources ◽  
Pollution Effect ◽  
The Impact ◽  
Effect Of Light

The article presents the results of the studies concerning the influence of a light source installed in luminaire of opal sphere type on the light pollution effect of the night sky. It is known from literature reports that the effect of light pollution is influenced by the spectral distribution of light. Although the influence of the spectral distribution has been widely studied from different perspectives, there is still a need to study this phenomenon—for example, from the point of view of the spectral reflection properties of the ground, on which the lanterns are installed. Hence, the above-mentioned aspect was considered in the authors’ investigations. The luminaire considered has been equipped with 20 different light sources, including the latest generation of lamps (light-emitting diodes, LEDs) as well as the conventional ones. With respect to these light sources, the measurements of light distribution and spectral distribution of emitted radiation of the luminaire were performed. Having these measurement data, the simulations were carried out using the DIALux software, and the calculations were made using the specially prepared calculation tool. On the basis of the results obtained in this way this was stated that the type of light source installed in the luminaire has a significant effect on the sky glow. An important factor affecting light pollution is not only the value of the luminous flux emitted upward but also the spectral characteristics of the emitted radiation, the impact of which is most noticeable. The conclusions from the studies indicate the next steps in the analysis of the light pollution effect. These steps will be focused on extended analysis of LEDs as modern and developed light sources.

A Study on the Effect of Light Sources on the Colour of Objects

2020 ◽  
pp. 47-52
Author(s):  
Fatih Atalar ◽  
Kerim Uzun ◽  
Ahmet Gedikli ◽  
Aysel Ersoy Yilmaz ◽  
Mukden Ugur
Keyword(s):  
Light Source ◽  
Light Sources ◽  
Halogen Lamp ◽  
White Led ◽  
Dominant Wavelength ◽  
Surface Type ◽  
Colour Temperature ◽  
Effect Of Light

Lighting is one of the basic aspects that eases our lives and increases its quality. We use lighting tools in many places such as homes, streets, work places, hospitals, factories, etc. In this study, the effects of the light source and the surface of the object on features like colour temperature, glare, colour (perceived) and dominant wavelength is analysed. Four light sources such as a warm white halogen lamp, warm white LED source and two cool white LED sources were used. In the light measurements, 10 paper surfaces and 8 cloth surfaces were selected as the surface type. Colours of the surfaces were selected among the main colours on the colour locus. Light, reflected from surface was recorded with Konica Minolta CS-200 model. All results were indicated and compared with each other.

LRT Digest 3: New colour metrics and their use

2019 ◽  
Vol 51 (5) ◽  
pp. 657-681 ◽  
Author(s):  
PR Boyce ◽  
JR Stampfli
Keyword(s):  
Light Source ◽  
Comprehensive Approach ◽  
Source Spectrum ◽  
Light Sources ◽  
Colour Properties ◽  
Executive Summary ◽  
Colour Temperature ◽  
Test Light ◽  
High Level ◽  
Colour Rendering

Executive summary The two metrics traditionally used to quantify the colour properties of light sources are the correlated colour temperature and the CIE General Colour Rendering Index. With the arrival of LEDs as a major light source questions began to be asked about the merits of both of these metrics. The question asked about correlated colour temperature was how far should the chromaticity of a light source be allowed to depart from the Planckian locus before the light emitted could no longer be said to be white? A tolerance to such a departure ( Duv) already existed but now gathered much more attention. The questions asked about the CIE General Colour Rendering Index were more searching. The limitations of the CIE General Colour Rendering Index were explored and, as a result, several alternative approaches to quantifying the colour rendition properties of light sources were proposed. The most comprehensive approach was produced by the Illuminating Engineering Society of North America, first in its Technical Memorandum IES TM-30-15 and more recently in its revision, Technical Memorandum ANSI/IES TM-30-18, which has been accepted as an American Standard. Both these documents describe a system that contains two high-level summary metrics: One for the average fidelity, i.e. how accurately a test light source renders 99 colour samples relative to how they are rendered under a reference illuminant, and the other for the average colourfulness, i.e. the overall increase or decrease in colourfulness of the same colour samples under the same test light source compared to the same reference illuminant. Associated with these overall average metrics are a number of more detailed metrics and graphical presentations. These aim to quantify and illustrate the variations in fidelity and the direction and magnitude of the shifts in chroma and hue around the hue circle. Compared to the CIE General Colour Rendering Index or the CIE Fidelity Index, a metric published by the CIE in 2017, ANSI/IES TM-30-18 provides a more comprehensive approach to quantifying and understanding the effects of light source spectrum on the perception of colour. Unfortunately, the new colour metrics described in IES TM-30-15 and ANSI/IES TM-30-18 have not yet been accepted by the CIE. Despite this, some light source manufacturers have started to provide information on their products expressed in terms of the ANSI/IES TM-30-18 colour metrics and designers are beginning to request them. The expectation is that, eventually, the ANSI/IES TM-30-18 metrics will be adopted by many countries and authorities, because they provide a much more comprehensive description of the colour properties of a light source than the CIE General Colour Rendering Index. This will be of value to light source manufacturers and lighting designers as well as those who prepare lighting codes and guides. It is expected that in the future the minimum set of data considered acceptable for describing the colour properties of a light source are likely to be the correlated colour temperature and the associated Duv value, the CIE Fidelity Index or the matching ANSI/IES TM-30-18 Fidelity Index, together with the ANSI/IES TM-30-18 Gamut Index and the ANSI/IES TM-30-18 Colour Vector Graphic.

scholarly journals Image analysis of particle size: effect of light source type

2019 ◽  
Vol 213 ◽  
pp. 02021 ◽  
Author(s):  
Roman Formánek ◽  
Bohuš Kysela ◽  
Radek Šulc
Keyword(s):  
Image Analysis ◽  
Light Source ◽  
Particle Diameter ◽  
Particle Size Effect ◽  
Light Sources ◽  
Halogen Lamp ◽  
Particle Sizes ◽  
Source Type ◽  
The Difference ◽  
Effect Of Light

Agitation of two immiscible liquids or solid-liquid suspension is a frequent operation in chemical and metallurgical industries. The sizes of particles, bubbles or droplets can be determined by the Image Analysis Technique. It is known that the quality of captured images depends significantly on the original image background that is mainly affected by the type of the light source. The aim of this contribution is to investigate the effect of light source type on image quality. The four types of light sources were tested: 1) 1000 W halogen lamp, 2) 72 W LED bar panel, 3) 60 W LED chip, and 4) 90 W LED chip. The illumination intensity and image background quality were investigated for each tested light sources. The effect of the shutter speed on evaluated particle sizes was tested using monodisperse spherical calibration particles having diameter of 1.19 mm. The difference observed between particle sizes evaluated by image analysis for given light source and declared calibration particle diameter was used as a measure of light source quality.

scholarly journals Photopolymerization of dental materials: Types and characteristics of the light sources

2009 ◽  
Vol 56 (4) ◽  
pp. 207-212 ◽  
Author(s):  
Gorjana Popovic ◽  
Roze Djokic
Keyword(s):  
Absorption Spectrum ◽  
Light Source ◽  
Uv Light ◽  
Dental Materials ◽  
Life Time ◽  
Source Spectrum ◽  
Light Sources ◽  
Light Spectrum ◽  
Visible Part ◽  
Short Time

Light from the polymerization source which initiates photopolymerization in the material has its determined wavelength. Photoinitiator, such as camphorhinone, excited by light, can be activated with any of the wavelength from its absorption spectrum. To obtain successful photopolymerization, light source should emit waves of adequate wavelength; light intensity has to be optimal, to have sufficient time of exposure and material up to 2 mm thickness. Photoinitiator inside the material should match light source spectrum and work regime. Halogen lamps have wide spectra of wavelengths in the visible part of the light spectrum. Their spectra are similar to absorption spectrum of camphorhinone. Plasma (xenon) lamps emit blue light. Though their diapason is low, spectra have great intensity. Adequate diapason and easy excitation allow them to have short time of exposure. LED lamps have blue diodes as light source. They do not need filters due to narrow emission spectrum. Laser (argon) lamps are the only that emit linear spectra. Ultraviolet (mercury) lamps are not in use any more in dentistry; theirs initiators were activated by UV light. LED lamps have longer life time; do not change the spectra during time, warm less, do not need filters, allow change of the source for more powerful, more efficient and more advantageous two steps or impulse illumination mode. However, LED lamps can not be used for a material that has photoinitiator(s) activated by light with wavelength above the maximum of the LED spectra.

scholarly journals Discomfort Glare Caused by White LED Light Sources-Effect of Light Source Position-

2006 ◽  
Vol 90 (11) ◽  
pp. 822-827 ◽  
Author(s):  
Hiroshi Takahashi ◽  
Takashi Irikura ◽  
Masahiro Toda ◽  
Takayoshi Moriyama
Keyword(s):  
Light Source ◽  
Light Sources ◽  
White Led ◽  
Source Position ◽  
Led Light ◽  
Discomfort Glare ◽  
Effect Of Light

Effects of light source spectrum and background colour on the perception of paintings

2019 ◽  
Vol 52 (1) ◽  
pp. 36-63
Author(s):  
L Bellia ◽  
F Fragliasso ◽  
E Stefanizzi
Keyword(s):  
Light Source ◽  
Light Emitting Diode ◽  
Source Spectrum ◽  
Light Emitting ◽  
Colour Temperature ◽  
Test Room ◽  
Led Light ◽  
Lighting Conditions ◽  
Set Up ◽  
Effect Of Light

This paper presents an experiment on the effect of light on the perception of paintings. The experiment was performed in a test-room where a typical museum exhibition set-up was simulated. Two different paintings were shown to 44 participants, under different light scenes obtained by using tuneable LED (Light Emitting Diode) wallwashers. To set the light scenes, the following parameters were modified: correlated colour temperature of the lighting, illuminance on the painting and the colour of the background wall. Participants answered a questionnaire to assess the perception of the paintings’ colours, the lighting conditions and the pleasantness of the exhibition set-up. The results demonstrated that illuminance is the parameter mainly affecting perception, for both paintings. However, correlated colour temperature and wall colour, as well as the combination of the three different considered parameters, can more or less influence perception depending on the chromatic composition of the painting.

Spectral characteristics of road surfaces and eye transmittance: Effects on energy efficiency of road lighting at mesopic levels

2017 ◽  
Vol 50 (6) ◽  
pp. 842-861 ◽  
Author(s):  
OU Preciado ◽  
ER Manzano
Keyword(s):  
Energy Efficiency ◽  
Light Source ◽  
Spectral Characteristics ◽  
The Other ◽  
Visual Performance ◽  
Light Sources ◽  
Surface Reflectance ◽  
Road Lighting ◽  
Road Surfaces ◽  
Final Effect

In 2010, the CIE published a recommended system for mesopic photometry based on visual performance. According to this system, scenes illuminated at mesopic levels with light sources of high S/P ratio, will produce better visual performance than those illuminated with light sources of a lower S/P ratio at equal photopic luminance. However, there could be other factors affected by SPD that, when quantified, could lead to a contradictory final effect. The scope of this paper was to evaluate how road lighting is affected by the spectral road surface reflectance and by the human eye transmittance as people get older. Our results suggest that the benefits of considering the mesopic vision effect for light sources with high S/P ratios are totally counteracted by the other two effects at mesopic luminances between 0.75 cd/m2 and 1.73 cd/m2 for people between 20 and 60 years of age, depending on the light source and the age of observers.

scholarly journals Influence of Peak Wavelengths on Properties of Mixed-LED White-Light Sources

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Snjezana Soltic ◽  
Andrew N. Chalmers
Keyword(s):  
Light Source ◽  
White Light ◽  
Light Sources ◽  
Peak Wavelength ◽  
White Light Source ◽  
Luminous Efficacy ◽  
Colour Temperature ◽  
Colour Rendering

The purpose of this investigation is to quantify the influence of the peak wavelength shifts in commercially available LEDs on the characteristics of the mixed-LED white-light sources. For this purpose, a tetrachromatic spectrum was optimized and then subjected to deviations in the peak wavelengths. A total of 882 combinations of peak wavelength values were evaluated, and the results are reported in terms of correlated colour temperature, colour-rendering properties, and radiant luminous efficacy. The results show that there can be significant changes in the characteristics of the source under these conditions. Such changes are highly likely to present problems when dealing with applications where an effective and accurate white-light source is important.

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