Colour preference, naturalness, vividness and colour quality metrics, Part 3: Experiments with makeup products and analysis of the complete warm white dataset

Light source colour quality is a complex phenomenon with several visual and cognitive components. Subjective colour preference, naturalness and vividness assessments of reddish cosmetic products in a viewing booth lit by light sources with a correlated colour temperature of 3200 K and to 550 lx were analysed and modelled by a new combined colour quality formula – a linear combination of a colour fidelity index and a measure of chroma change. Results of the warm white light sources described in all three parts of this work were merged. They were modelled by optimising the parameters of the same formula. The formula supports multi-LED light sources with moderately accentuated local spectral maxima to enhance object chroma over a moderate range.

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Colour preference, naturalness, vividness and colour quality metrics, Part 1: Experiments in a room

Lighting Research and Technology ◽

10.1177/1477153516643359 ◽

2016 ◽

Vol 49 (6) ◽

pp. 697-713 ◽

Cited By ~ 26

Author(s):

TQ Khanh ◽

P Bodrogi ◽

QT Vinh ◽

D Stojanovic

Keyword(s):

Quality Metrics ◽

Saturation Effect ◽

Light Sources ◽

Quality Indices ◽

Colour Preference ◽

Colour Temperature ◽

Semantic Categories ◽

Interval Scales ◽

Office Lighting ◽

Spectral Design

In Part I of this work, observers scaled colour preference, naturalness and vividness visually on interval scales (0–100) labelled by semantic categories (e.g. ‘moderate’, ‘good’ and ‘very good’) in the context of office lighting. Five customary light sources without object saturation effect illuminated a table with coloured objects in a real room. The observers’ assessments were predicted by recent colour quality indices and selected pairs of indices combined linearly. Criterion values of the indices for ‘good’ colour preference and vividness were determined to provide a usable acceptance limit for the spectral design and evaluation of light sources. To predict colour preference, correlated colour temperature turned out to be useful. In Part 2 of this work, another experiment with the same method but using multi-LED spectra with more object saturation will be analysed and the two datasets will be merged.

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Interactive effect of illuminance and correlated colour temperature on colour preference and degree of white light sensation for Chinese observers

Optik ◽

10.1016/j.ijleo.2020.165675 ◽

2020 ◽

Vol 224 ◽

pp. 165675

Author(s):

Yu Wang ◽

Qiang Liu ◽

Wenyu Gao ◽

Michael R. Pointer ◽

Zheng Huang ◽

...

Keyword(s):

White Light ◽

Interactive Effect ◽

Colour Preference ◽

Colour Temperature

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Low-Cost Extra-Low Voltage LED Dimmer for Tuneable White Lighting

Elektronika ir Elektrotechnika ◽

10.5755/j01.eie.25.3.23675 ◽

2019 ◽

Vol 25 (3) ◽

pp. 43-49

Author(s):

Roman Hrbac ◽

Tomas Mlcak ◽

Vaclav Kolar ◽

Tomas Vantuch

Keyword(s):

White Light ◽

Low Voltage ◽

Low Cost ◽

Light Output ◽

Electrical Performance ◽

Light Sources ◽

Colour Temperature ◽

Lighting Systems ◽

Module Efficiency ◽

The Right

The colour appearance of light sources has a major impact on how people perceive space. With LED illumination lighting, the colour output can be tuned to virtually any perceivable colour, including any hue of white light. It has been established that the right shade of white light during the 24-hour day cycle has a positive effect on the human body's biological system. For this reason, it is very important to focus on the development and application of new lighting systems that have dynamically variable light outputs in order to imitate the sunlight. Circadian regulation is most responsive to short-wavelength light (460 nm = blue colour). This paper describes the development of a low-cost extra-low voltage LED dimmer for tunable white lighting systems aiming to achieve maximum electrical performance and light-output. This dimming module has two independent LED control channels and allows for a variable colour temperature control from warm white to cold white light. Experimental results of the dimming module efficiency measurements, correlated colour temperature (CCT), colour rendering index (CRI), illuminance and power consumption of the luminaire depending on the duty cycle for different control frequencies (200 Hz, 1.5 kHz, 5 kHz, 10 kHz and 20 kHz) are presented. The paper further describes the principle of creating control curves for an independent regulation of correlated colour temperature and illuminance. In the form of a table, the control curve outputs may be uploaded into a microcontroller. The paper details the construction, function and the advantages of this LED dimmer prototype.

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

Advances in OptoElectronics ◽

10.1155/2010/437564 ◽

2010 ◽

Vol 2010 ◽

pp. 1-8 ◽

Cited By ~ 2

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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Towards an optimum colour preference metric for white light sources: a comprehensive investigation based on empirical data

Optics Express ◽

10.1364/oe.413389 ◽

2021 ◽

Vol 29 (5) ◽

pp. 6302

Author(s):

Zheng Huang ◽

Wei Chen ◽

Qiang Liu ◽

Yu Wang ◽

Michael R. Pointer ◽

...

Keyword(s):

White Light ◽

Empirical Data ◽

Light Sources ◽

Colour Preference ◽

Comprehensive Investigation

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The Influence Of The Led Luminaires Electrical Parameters On Their Correlated Colour Temperature During Operation Mode

Light & Engineering ◽

10.33383/2020-025 ◽

2020 ◽

pp. 89-96

Author(s):

Sergei S. Kapitonov ◽

Alexei S. Vinokurov ◽

Sergei V. Prytkov ◽

Sergei Yu. Grigorovich ◽

Anastasia V. Kapitonova ◽

...

Keyword(s):

Operation Mode ◽

Light Sources ◽

Electrical Parameters ◽

Colour Temperature ◽

Radiation Spectra ◽

Service Period ◽

Close Proximity ◽

Definition Of ◽

Comprehensive Study

The article describes the results of comprehensive study aiming at increase of quality of LED luminaires and definition of the nature of changes in their correlated colour temperature (CCT) in the course of operation. Dependences of CCT of LED luminaires with remote and close location of phosphor for 10 thousand hours of operation in different electric modes were obtained; the results of comparison between the initial and final radiation spectra of the luminaires are presented; using mathematical statistics methods, variation of luminaire CCT over the service period claimed by the manufacturer is forecast; the least favourable electric operation modes with the highest CCT variation observed are defined. The obtained results have confirmed availability of the problem of variation of CCT of LED luminaires during their operation. Possible way of its resolution is application of more qualitative and therefore expensive LEDs with close proximity of phosphor or LEDs with remote phosphor. The article may be interesting both for manufacturers and consumers of LED light sources and lighting devices using them.

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