Journal articles: 'Correlated colour temperature'

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Gardner, J. L. "Correlated colour temperature - uncertainty and estimation." Metrologia 37, no. 5 (October 2000): 381–84. http://dx.doi.org/10.1088/0026-1394/37/5/8.

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Huang, Z., Q. Liu, S. Westland, MR Pointer, M. Ronnier Luo, and K. Xiao. "Light dominates colour preference when correlated colour temperature differs." Lighting Research & Technology 50, no. 7 (June 6, 2017): 995–1012. http://dx.doi.org/10.1177/1477153517713542.

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Colour preference for lighting is generally influenced by three kinds of contextual factors, the light, the object and the observer. In this study, a series of psychophysical experiments were conducted to investigate and compare the effect of certain factors on colour preference, including spectral power distribution of light, lighting application, observers’ personal colour preference, regional cultural difference and gender difference. LED lights with different correlated colour temperatures were used to illuminate a wide selection of objects. Participant response was quantified by a 7-point rating method or a 5-level ranking method. It was found that the preferred illumination for different objects exhibited a similar trend and that the influence of light was significantly stronger than that of other factors. Therefore, we conclude that the light itself (rather than, e.g. the objects that are viewed) is the most crucial factor for predicting which light, among several candidates with different correlated colour temperatures, an observer will prefer. In addition, some of the gamut-based colour quality metrics correlated well with the participants’ response, which corroborates the view that colour preference is strongly influenced by colour saturation. The familiarity of the object affects the ratings for each experiment while the colour of the objects also influences colour preference.

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Gardner, J. L. "Uncertainties in source distribution temperature and correlated colour temperature." Metrologia 43, no. 5 (September 12, 2006): 403–8. http://dx.doi.org/10.1088/0026-1394/43/5/010.

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Mundinger, JJ, and KW Houser. "Adjustable correlated colour temperature for surgical lighting." Lighting Research & Technology 51, no. 2 (November 24, 2017): 280–90. http://dx.doi.org/10.1177/1477153517742682.

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A surgical luminaire containing two types of phosphor-converted LEDs was employed to illuminate a large midline incision in a 90 kg pig. The PC-LEDs were proportionally blended to create four spectra defined by their approximate correlated colour temperatures: 3000, 4000, 4500 and 5100 K. Sixteen surgeons evaluated the colour appearance of internal anatomy under each spectrum. All four spectra were rated as highly effective. There was no significant difference between the 4000, 4500 and 5100 K spectra. The 3000 K spectrum was rated as less effective, though this does not mean it was ineffective. The spectrum by participant interaction was significant where it could be estimated, suggesting that surgeons may develop individual opinions about which spectra are most effective. While the surgeons moderately agreed that the colour of internal anatomy was altered by the different spectra, they were undecided whether the differences would increase the risk of surgical error or influence surgical decisions. They were also largely undecided whether they would select different spectra during a single procedure, for different procedures, or for different anatomy. Overall, the linear mixing for variable CCT employed in this experiment did not provide obvious utility for surgeons making visual evaluations.

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Borbély, Ákos, Árpád Sámson, and János Schanda. "The concept of correlated colour temperature revisited." Color Research & Application 26, no. 6 (October 8, 2001): 450–57. http://dx.doi.org/10.1002/col.1065.

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Krystek, M. "An algorithm to calculate correlated colour temperature." Color Research & Application 10, no. 1 (1985): 38–40. http://dx.doi.org/10.1002/col.5080100109.

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te Kulve, Marije, Luc Schlangen, Lisje Schellen, Jan L. Souman, and Wouter van Marken Lichtenbelt. "Correlated colour temperature of morning light influences alertness and body temperature." Physiology & Behavior 185 (March 2018): 1–13. http://dx.doi.org/10.1016/j.physbeh.2017.12.004.

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Huang, Z., Q. Liu, MR Luo, MR Pointer, B. Wu, and A. Liu. "The whiteness of lighting and colour preference, Part 2: A meta-analysis of psychophysical data." Lighting Research & Technology 52, no. 1 (March 24, 2019): 23–35. http://dx.doi.org/10.1177/1477153519837946.

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In this work, the correlation between the perceived whiteness of lighting and the corresponding colour preference of observers was comprehensively investigated based on the data of 19 groups of experiments collected from 14 studies. The dataset included 13 experiments with constant correlated colour temperature and 6 experiments with multiple correlated colour temperatures, with illuminance levels ranging from 200 lx to 500 lx. For the five studies implemented by the authors, the subjective ratings of colour preference and the whiteness of lighting were acquired. For other cases, only the preference ratings were collected while the whiteness of lighting was quantified by a measure named degree of neutrality ( Sneutral), which has been validated in our previous work. The meta-analysis results confirm our former statement that people prefer whiter illumination and further specify its prerequisite. That is, the whiteness of lighting generally correlates well with colour preference under the conditions where the candidate lights differed to a certain extent in white. In addition, it was further demonstrated that for the scenarios with multiple correlated colour temperatures ranging from 2500 K to 5500 K people indeed preferred perceptually whiter light chromaticities, while for correlated colour temperatures higher than 5500 K it seemed that they appeared too cold to be preferred.

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Baniya, Rupak R., Eino Tetri, Jukka Virtanen, and Liisa Halonen. "The effect of correlated colour temperature of lighting on thermal sensation and thermal comfort in a simulated indoor workplace." Indoor and Built Environment 27, no. 3 (October 6, 2016): 308–16. http://dx.doi.org/10.1177/1420326x16673214.

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The ‘hue-heat’ hypothesis states that an environment which has wavelengths predominantly toward the red end of the visual spectrum feels ‘warm’ and one with wavelengths mainly toward the blue end feels ‘cool’. In order to test the hypothesis and to study the impacts of the correlated colour temperature of a light source on thermal sensation and thermal comfort, a study was conducted in a test room illuminated with an Light Emitting Diode (LED) lighting system with an adjustable correlated colour temperature where air temperature, air velocity, and relative humidity were kept constant. The correlated colour temperature of lighting inside the test room was changed gradually while keeping the colour rendering index values greater than 90, an illuminance level of 500 lx, and chromaticity difference (Duv) values within the limits of ±0.005. Sixteen study subjects were exposed to a ‘high room temperature’ (25℃) and a ‘low room temperature’ (20℃) on different days. The subjects were adapted to low correlated colour temperature (2700 K), medium correlated colour temperature (4000 K), and high correlated colour temperature (6200 K) lighting for 10 min and subsequently completed the questionnaire about their thermal comfort and thermal sensation. The results of this survey did not provide support for the hue-heat hypothesis and indicated that people felt thermally more comfortable in an indoor workplace at the correlated colour temperature of 4000 K than at the correlated colour temperature of 2700 K or 6200 K.

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Khanh, TQ, P. Bodrogi, QT Vinh, X. Guo, and TT Anh. "Colour preference, naturalness, vividness and colour quality metrics, Part 4: Experiments with still life arrangements at different correlated colour temperatures." Lighting Research & Technology 50, no. 6 (March 24, 2017): 862–79. http://dx.doi.org/10.1177/1477153517700705.

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Subjective colour preference, naturalness and vividness assessments of two different colourful still life arrangements viewed in a real room were analysed and modelled with the aid of the Rf colour fidelity metric combined with a chroma difference metric. Coloured objects were illuminated by a four-channel LED light engine with 36 different spectra at four correlated colour temperatures and nine object oversaturation levels. Results imply a significant dependence of the subjective judgments on correlated colour temperature.

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Chakrabarti, M., A. Thorseth, DD Corell, and C. Dam-Hansen. "A white–cyan-red LED system for low correlated colour temperature lighting." Lighting Research & Technology 49, no. 3 (September 28, 2015): 343–56. http://dx.doi.org/10.1177/1477153515608416.

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A white LED complemented by cyan and red LEDs is a good candidate for achieving high colour rendering at low correlated colour temperatures. This is usually very difficult with commercially available white LEDs. In addition, the system is able to replace incandescent lighting in many applications; for example, the lighting for museum display cases. To investigate and optimize the colour and light distribution properties, both spectral and geometrical modelling are used. Mapping of the possible combinations of LEDs is used to locate the optimal solutions within the colour gamut, with emphasis on chromaticity and colour rendering indices. A geometric optical model is used to design and optimize the homogeneity of the colour and light intensity distribution as a function of angle. The resulting system produces diffused homogeneous white light with a tunable correlated colour temperature from 2000 K to 2400 K. Within this range the white light is characterized by a high general colour rendering index (Ra > 90), special colour rendering indices for saturated red objects (R9 > 85), and low chromaticity distance (Duv) from the Planckian locus (Duv < 2 × 10−3).

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Fontecha, J., J. Campos, A. Corr ns, and A. Pons. "An analytical method for estimating correlated colour temperature uncertainty." Metrologia 39, no. 6 (December 1, 2002): 531–36. http://dx.doi.org/10.1088/0026-1394/39/6/3.

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Fu, Tairan, Xiaofang Cheng, Bo Wu, and Zhenglin Zhu. "Study of correlated colour temperature and thermodynamic temperature of a radiating source." Metrologia 41, no. 6 (November 23, 2004): 439–43. http://dx.doi.org/10.1088/0026-1394/41/6/012.

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Stanikūnas, Rytis, Laimonas Puišys, Aldona Radzevičienė, and Henrikas Vaitkevičius. "Colour Preference for Two-Colour Combinations." Psichologija 61 (July 7, 2020): 8–20. http://dx.doi.org/10.15388/psichol.2020.12.

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What determines which colour combinations will be attractive to a person and which will not? Is colour attractiveness only a subjective human experience, or can we predict it based on physical colour parameters? One of the pioneers of the attraction of colour theories was Michel Eugène Chevreul (1786–1889). He distinguished two types of colour harmony – analog colour and contrast – and tried to describe what harmonics are based on physical colour parameters. This was later done by other scientists. Later, semantic evaluation of colours was introduced and factor analysis attempted to identify emotions caused by colours or combinations of colours. The aim of this research is to test whether there is a consistent pattern of judgments of colour combinations under controlled conditions and, if so, to what extent they are influenced by the objective physical characteristics of those combinations. Subjects. The study involved 40 students (20 men, 20 women). All subjects had normal colour vision and were not related to fine art. Research tools. The study used 8 colours: 4 opponent (green, red, yellow and blue) and 4 additional (orange, lettuce, blue and purple). The 28 colour combinations (made up of two different colours) were composed of those 8 colours and printed onto cardboard card where each colour had area of 80 mm x 80 mm. Questionnaire of 40 adjectives consisting of 20 pairs of antonyms were used for semantic colour assessment. Procedure. The investigation was conducted in a dark room. Initially, all 28 cards with colour combinations were placed randomly on a desk lit by a 40 cm high fluorescent lamp (4000K correlated colour temperature). The subject was asked to select one of the cards with the most preferable colour combination, to write its code on the questionnaire and to mark all the epithets in the questionnaire which suits this colour combination. The same procedure was applied to the all other cards. One experiment lasted 35–50 minutes. Results and conclusions. Independent component analysis distinguished 4 dimensions describing colours: pleasure, energy, purple color and strength. Logistic regression analysis was run on colour factor loadings to discriminate colour combinations into two groups: liked and disliked colour combinations. It shows that that colour combination could be predicted as being liked or disliked with 85% probability. Adding physical colour parameters to the regression increases prognostic probability to 92 %. Also a relationship between subjective factors and physical characteristics of colour combinations was found. Pleasure correlates with hue contrast and strength with saturation contrast. It can be argued that the reliability of colour combinations is determined by both subjective and physical factors.

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Khanh, TQ, P. Bodrogi, X. Guo, QT Vinh, and S. Fischer. "Colour preference, naturalness, vividness and colour quality metrics, Part 5: A colour preference experiment at 2000 lx in a real room." Lighting Research & Technology 51, no. 2 (October 20, 2017): 262–79. http://dx.doi.org/10.1177/1477153517737133.

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Subjects rated the colour preference of a colourful object scene illuminated to 2000 lx by 28 different spectra from a four-channel LED light engine at different object saturation levels and different white points (3200 K, 4200 K, 5000 K and 5600 K). Mean colour preference ratings had a maximum at a moderate saturation level. The lowest correlated colour temperature (3200 K) exhibited lower preference ratings than the three higher correlated colour temperatures. The influence of saturation level was modelled by existing colour rendition measures and by the measure colour quality combining a colour fidelity index and an overall object colour object saturation measure taken from Part 4 of this work.

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Xu, L., MR Luo, and M. Pointer. "The development of a colour discrimination index." Lighting Research & Technology 50, no. 5 (March 6, 2017): 681–700. http://dx.doi.org/10.1177/1477153517691331.

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One aspect of colour rendering is to discern the difference between colours and colour discrimination. This is important for applications such as surgical procedures and industrial inspection. Two psychophysical experiments were conducted using computer generated images and real materials, including stone, wood and organs. The results were used to develop a colour discrimination index which includes three components: the CAM02-UCS uniform colour space, the correlated colour temperature and a set of test samples.

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Prytkov, Sergey V., and Maxim V. Kolyadin. "Error Estimation For The Methods Of Correlated colour Temperature Calculation." Issue 03-2021, no. 03-2021 (June 2021): 70–77. http://dx.doi.org/10.33383/2021-018.

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To date, a lot of methods have been developed for calculating correlated colour temperature (CCT). There are both numerical solutions (Robertson’s method, Yoshi Ohno method, binary search algorithm) and analytical (Javier Hernandez-Andres’s method, McCamy’s method). At the same time, the information about their accuracy is of a segmental fragmentary nature, therefore, it is very difficult to develop recommendations for the application of methods for certain radiators. In this connection, it seems extremely interesting to compare the error of the most well-known CCT calculating methods, using a single universal approach. The paper proposes an algorithm for researching the error of the methods for calculating correlated colour temperature, based on the method for plotting lines of constant CCT of a given length. Temperatures corresponding to these lines are taken as true, and the chromaticity lying on them are used as input data for the researched method. The paper proposes an approach when first the distribution of the error in the entire range of determination of CCT is determined, followed by bilinear interpolation for the required chromaticity. Using this approach, the absolute errors of the following methods for calculating CCT: McCamy, Javier Hernandez, Robertson, and Yoshi Ohno were estimated. The error was estimated in the range occupied by quadrangles of possible values from ANSI C78.377 chromaticity standard, developed by American National Standards Institute for LED lamps for indoor lightning. The tabular and graphical distribution of the absolute error for each investigated method was presented in the range of (2000–7000) K. In addition, to clarify the applicability of the methods for calculating CCT of the sky, the calculation of the distribution of the relative error up to 100000 K was performed. The results of the study can be useful for developers of standards and measurement procedures and for software developers of measuring equipment.

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Boyce, P. R., and C. Cuttle. "Effect of correlated colour temperature on the perception of interiors and colour discrimination performance." Lighting Research & Technology 22, no. 1 (March 1990): 19–36. http://dx.doi.org/10.1177/096032719002200102.

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Fabregat, J., V. Reglero, J. Suso, and J. E. Armentia. "Activity, Colour Anomalies and Temperature Determination in Solar-type Stars." International Astronomical Union Colloquium 130 (1991): 333–35. http://dx.doi.org/10.1017/s0252921100079860.

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The presence of photometric anomalies in broad band colours produced by chromospheric activity was first suggested by Campbell (1984). He defined the colour anomaly δ(B–V)V–K as the deviation from the mean relation (B–V)–(V–K) for Hyades dwarfs, and found this anomaly correlated well with several activity indicators.Since the work of Campbell, several authors have discussed the relation between activity and colour anomalies, obtaining diverging results. This discussion is relevant because long baseline photometric colours are the most reliable temperature indicators, and the presence of such anomalies implies that no consistent temperature scales can be obtained for stars with different activity levels. These topics have been recently reviewed by Soderblom (1989).

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Fotios, S., and Q. Yao. "The association between correlated colour temperature and scotopic/photopic ratio." Lighting Research & Technology 51, no. 5 (July 3, 2018): 803–13. http://dx.doi.org/10.1177/1477153518779637.

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The scotopic/photopic ratio (S/P) is a parameter that may be considered in the design of road lighting. This paper compares the S/P ratio and correlated colour temperature (CCT) for 297 light source spectra identified in IES Technical Memorandum TM-30-15 to test the assumption that higher S/P ratios demand higher CCTs. The results suggest that, for a given lamp type, there is a strong association between S/P ratio and CCT, and hence that for a given CCT only a small variation in S/P ratio is available. However, the results also suggest that a larger variation in S/P ratio is possible if the lighting designer is able to consider a change in lamp type.

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Brambilla, Arianna, Wenye Hu, Reza Samangouei, Rebecca Cadorin, and Wendy Davis. "How correlated colour temperature manipulates human thermal perception and comfort." Building and Environment 177 (June 2020): 106929. http://dx.doi.org/10.1016/j.buildenv.2020.106929.

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Bellia, L., F. Fragliasso, and E. Stefanizzi. "Effects of light source spectrum and background colour on the perception of paintings." Lighting Research & Technology 52, no. 1 (June 11, 2019): 36–63. http://dx.doi.org/10.1177/1477153519847254.

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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.

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Dang, R., N. Wang, G. Liu, and H. Tan. "Four-component, white LED with good colour quality and minimum damage to traditional Chinese paintings." Lighting Research & Technology 51, no. 7 (January 15, 2019): 1077–91. http://dx.doi.org/10.1177/1477153518819039.

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A correlated colour temperature tunable, four-component, LED system suitable for illuminating traditional Chinese paintings painted with inorganic pigments (iop-TCPs) has been designed. This light source can meet the requirements for protective illumination and colour quality in museum illumination. The damage to iop-TCPs caused by the individual 450 nm, 510 nm, 583 nm and 650 nm monochromatic LEDs used to construct the LED system were obtained through a long-term illumination experiment. Then, we calculated the damage resulting from the corresponding four-component white LEDs with various spectral power distributions, the intensities of which were iterated by a brute force algorithm. The constructed spectral power distributions were evaluated by the damage and colour quality formulae. The results showed that the better colour quality spectral power distributions with higher correlated colour temperatures cause less damage to iop-TCPs. The lowest damage spectral power distributions, satisfying colour quality requirements with correlated colour temperatures ranging from 2700 K to 4000 K, were obtained by calculating the corresponding parameters of the formed spectral power distributions and further selection. This paper not only provides a colour temperature tunable, four-component, white LED system suitable for illuminating iop-TCPs but also sets out a methodology that can be used to identify white LEDs suitable for other cultural relics based on damage limitation and visual requirements.

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Kalustova, Daria, Vasyl Kornaga, Andrii Rybalochka, Ying-Jie Yu, and Sergiy Valyukh. "Colour temperature tunable RGBW clusters with 3 control channels." Photonics Letters of Poland 12, no. 1 (March 31, 2020): 10. http://dx.doi.org/10.4302/plp.v12i1.968.

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The work is devoted to development of a smart lighting system that is able to change correlated colour temperature and consists of tunable 4-components RGBW clusters controlled via three channels. It is shown that fixing a ratio between the intensities of white and red LEDs at a level of 100:9 enables obtaining high values of colour rendering in a wide range of correlated colour temperatures. A control of 3 from 4 channels simplifies the system. The influence of the red LED on CRI and luminous efficiency is analysed. Full Text: PDF References:J. Gooley, S. Rajaratnam, G. Brainard, R. Kronauer, C. Czeisler and S. Lockley, "Spectral Responses of the Human Circadian System Depend on the Irradiance and Duration of Exposure to Light", Sci Transl Med 2, 31 (2010) [CrossRef]A. Borisuit, F. Linhart, J. Scartexxini, M. Munch, Light Res Technol 47, 192 (2014) [CrossRef]Q. Dai, W. Cai, L. Hao, W Shi and Z. Wang, Light Res Technol 50 (8), 1198-1211 (2017), [CrossRef]V. Kornaga, V. Sorokin, A. Rybalochka, O. Oliinyk and N. Kornaga, Semicond Phys Quantum Electron Optoelectron 18, 302 (2015) [CrossRef]Illuminating Engineering Society, ANSI/IES TM-30-18 IES method for evaluating light source color rendition (2018). New York, NY[DirectLink]Commission International de l'Éclairage, CIE 224:2017 Colour fidelity index for accurate scientific use (2017). Vienna [CrossRef]V. Kornaga, D. Kalustova and O. Oliynyk, Int Sci Conf "Light and power eng: hist, probl, perspect" 6, 43 (2018) [DirectLink]

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Ye, M., SQ Zheng, ML Wang, and M. Ronnier Luo. "The effect of dynamic correlated colour temperature changes on alertness and performance." Lighting Research & Technology 50, no. 7 (February 14, 2018): 1070–81. http://dx.doi.org/10.1177/1477153518755617.

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Light can have acute effects on human performance, including task performance, alertness and circadian phase shift. Most studies have investigated these effects using static light. This study investigates the effects of dynamic light with different cycle times and different ranges of correlated colour temperature on human alertness and task performance. Ten participants took part in the experiment using six conditions of dynamic light with each observing session lasting 4.5 hours. An electroencephelogram, measurements of critical flicker frequency, performance on various cognitive tasks and alertness and sleepiness questionnaires were used to evaluate the human responses. The results showed that participants appeared more alert and performed better under lighting of higher correlated colour temperature range but different correlated colour temperature cycle times had little effect.

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Truong, William, Babak Zandi, Vinh Quang Trinh, and Tran Quoc Khanh. "Circadian metric – Computation of circadian stimulus using illuminance, correlated colour temperature and colour rendering index." Building and Environment 184 (October 2020): 107146. http://dx.doi.org/10.1016/j.buildenv.2020.107146.

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Huang, Z., Q. Liu, Y. Liu, MR Pointer, MR Luo, Q. Wang, and B. Wu. "Best lighting for jeans, part 1: Optimising colour preference and colour discrimination with multiple correlated colour temperatures." Lighting Research & Technology 51, no. 8 (December 13, 2018): 1208–23. http://dx.doi.org/10.1177/1477153518816125.

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In this study, two psychophysical experiments, one on colour preference and the other on colour discrimination, were conducted. To investigate the colour preference for blue jeans, 27 subjects with normal colour vision were asked to rate their visual appreciation of seven pairs of jeans with a colour gradient pattern. Nine LEDs, with uniformly sampled correlated colour temperature (CCT) values ranging from 2500 K to 6500 K, were used to illuminate the jeans. These lights produced a constant illuminance of approximately 200 lux, and their colour rendering indexes were between 79 and 91. In addition, using a Farnsworth-Munsell (FM)-100 Hue Test, the blue-region colour discrimination of 42 observers was assessed for five LEDs of the same type but with different CCTs (2500 K–6500 K, 1000 K interval). The results indicate that there is an optimum CCT of 5500 K for jeans, at which observers were found to exhibit the greatest capability for colour discrimination and the highest rating for colour preference. Interestingly, a significant gender difference was found in this study, which had not been observed in our previous work with quite similar experimental settings but different experimental objects. The findings of this study should provide a deeper understanding for the lighting design of shopping malls for jeans.

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Hartstein, LE, MT Durniak, RF Karlicek, and NE Berthier. "A comparison of the effects of correlated colour temperature and gender on cognitive task performance." Lighting Research & Technology 50, no. 7 (July 25, 2017): 1057–69. http://dx.doi.org/10.1177/1477153517721728.

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Higher correlated colour temperature ambient lighting, which contains more blue light, has been reported to improve performance on a variety of cognitive tasks. The current investigation compared performance of adults on what/where task switching, go/no-go, and mental rotation tasks when the experimental room was lit by 3500 K standard florescent and 5000 K LED lighting. Results showed that, under higher correlated colour temperature illumination, females (but not males) decreased reaction time by approximately 10% on the task switching task, that males (but not females) showed a reaction time decrease on the go/no-go tasks, and that no effect was observed on the mental rotation task. Our results suggest that higher correlated colour temperature illumination improves reaction time performance on certain attention/executive function tasks, but that that improvement is gender specific.

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Dang, Rui, Wenli Guo, and Tao Luo. "Correlated colour temperature index of lighting source for polychrome artworks in museums." Building and Environment 185 (November 2020): 107287. http://dx.doi.org/10.1016/j.buildenv.2020.107287.

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Smolders, Karin C. H. J., and Yvonne A. W. de Kort. "Investigating daytime effects of correlated colour temperature on experiences, performance, and arousal." Journal of Environmental Psychology 50 (June 2017): 80–93. http://dx.doi.org/10.1016/j.jenvp.2017.02.001.

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Ghosh, Aritra, Prabhu Selvaraj, Senthilarasu Sundaram, and Tapas K. Mallick. "The colour rendering index and correlated colour temperature of dye-sensitized solar cell for adaptive glazing application." Solar Energy 163 (March 2018): 537–44. http://dx.doi.org/10.1016/j.solener.2018.02.021.

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Lu, Y., W. Li, W. Xu, and Y. Lin. "Impacts of LED dynamic white lighting on atmosphere perception." Lighting Research & Technology 51, no. 8 (January 31, 2019): 1143–58. http://dx.doi.org/10.1177/1477153518823833.

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This paper investigated atmosphere perception as dynamic white lighting varied in illuminance or correlated colour temperature in different directions and with different functional forms of change. Fifteen Chinese observers evaluated 32 dynamic lighting stimuli. A 13-scale questionnaire was employed for each stimulus. Factor analysis was adopted to examine the gender difference and the effect on atmosphere perception. Two dimensions of atmosphere perception were obtained and identified as coziness and liveliness for both illuminance change and correlated colour temperature change. Gender differences exist mostly on the scales ‘informal-formal’ and ‘slow–fast’. Dynamic white lighting shows significant influence on atmosphere perception. For illuminance changes, high correlated colour temperature levels are useful to create liveliness and a formal atmosphere. Liveliness also increases when the light level rises. A linear change increases coziness most and produces the slowest perceived speed of change. For dynamic light variations in correlated colour temperature, changes under high illuminance level or changes from warmer light to cooler light create liveliness. Perceived evenness tends to decrease when the light level rises. Linear and quadratic changes offer the coziest atmosphere. Further studies are needed but the effect should be considered when designing dynamic lighting installations or when dimming for numerous applications.

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Khanh, TQ, P. Bodrogi, X. Guo, and PQ Anh. "Towards a user preference model for interior lighting. Part 2: Experimental results and modelling." Lighting Research & Technology 51, no. 7 (December 13, 2018): 1030–43. http://dx.doi.org/10.1177/1477153518816474.

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Subjects assessed their visual impressions about scene brightness, visual clarity, colour preference and scene preference in a real room in which the horizontal illuminance, the correlated colour temperature and the level of chroma enhancement of the light source were changed systematically. The aim of the experiment is to contribute to the development of a user preference model. The concept of this model and the experimental method were described in Part 1 of this work. In Part 2, modelling equations of these four visual attributes and their validation are shown. Criterion illuminance levels for ‘good’ levels of the visual attributes were determined depending on correlated colour temperature.

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Xiong, Mei, Mengli Zhao, Zhen-Xiang Lu, and Parthiba Balasubramanian. "Genotypic variation for phenolic compounds in developing and whole seeds, and storage conditions influence visual seed quality of yellow dry bean genotypes." Canadian Journal of Plant Science 100, no. 3 (June 1, 2020): 284–95. http://dx.doi.org/10.1139/cjps-2019-0153.

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Seed coat colour is an important determinant of the visual quality of dry beans, as seeds are sold as a dry commodity. Phenolic compounds have a major effect on the colour of bean seeds. The objectives of the study were to determine the changes in phenolic compounds during seed development and in whole seeds of yellow bean genotypes with contrasting seed coat colour, and the effects of storage temperature and duration on seed phenolics and colour. Condensed tannin, phenolic acid, flavonoids, and antioxidant activity were observed as early as 10 d after flowering in the developing seeds of Arikara Yellow, which darken at harvest and during postharvest storage. In contrast, for CDC Sol and AAC Y073 seeds which remain yellow, phenolic compounds and antioxidant activity were consistently low. Seed brightness (L*) and yellow colour (b*) were negatively correlated with phenolic compounds and antioxidant activity, and conversely seed redness (a*) was positively correlated with phenolic compounds, confirming a negative influence of phenolic compounds on seed coat colour. Yellow bean genotypes had low anthocyanin but were high in β-carotene. Storage temperature influenced condensed tannin and seed coat colour, whereas the duration of storage influenced phenolic compounds, antioxidant activity, and seed coat colour. Higher temperatures (20 or 30 °C) and longer storage duration (120 or 180 d) generally resulted in darker seeds with increasing redness compared with seeds stored at 6 °C or for 60 d. AAC Y073 and CDC Sol with improved seed coat colour may increase consumer preference, value, and marketability of yellow beans.

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Shimizu, Masanori, Izumi Okamura, and Takeshi Inoue. "Study on relation between correlated colour temperature and discomfort glare of light sources." JOURNAL OF THE ILLUMINATING ENGINEERING INSTITUTE OF JAPAN 74, Appendix (1990): 72. http://dx.doi.org/10.2150/jieij1980.74.appendix_72.

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Das, Sagnik, Uttam Kumar Ghorai, Rajib Dey, Chandan Kumar Ghosh, and Mrinal Pal. "Novel multiple phosphorescence in nanostructured zinc oxide and calculations of correlated colour temperature." Physical Chemistry Chemical Physics 19, no. 34 (2017): 22995–3006. http://dx.doi.org/10.1039/c7cp03631k.

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A thermodynamic explanation using defect chemistry for the temperature and atmosphere dependent novel multiple phosphorescence in ZnO nanoparticles (∼160 nm) fit for cool lighting application is reported.

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37

Bodrogi, P., Y. Lin, X. Xiao, D. Stojanovic, and TQ Khanh. "Intercultural observer preference for perceived illumination chromaticity for different coloured object scenes." Lighting Research & Technology 49, no. 3 (November 24, 2015): 305–15. http://dx.doi.org/10.1177/1477153515616435.

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The preference for the chromaticity of high illuminance, high colour rendering LED illumination of different scenes was investigated for Chinese and European observers. An experiment about the preference for perceived illumination chromaticity was conducted with the same multi-LED light engine, same viewing booth and same coloured objects transported between Germany and China. Observer preference for perceived illumination chromaticity was significantly influenced by correlated colour temperature (2700 K–6500 K), object scene colour (red, blue or mixed), cultural background (Chinese or European origin, living in Germany or in China) and gender (men, women). The results can be used to choose an appropriate correlated colour temperature (e.g. warm white or cool white) for a high-quality lighting product to illuminate different object scenes (e.g. red or blue objects) so as to achieve good user acceptance in the global market.

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Maiti, PK, and B. Roy. "Evaluation of a daylight-responsive, iterative, closed-loop light control scheme." Lighting Research & Technology 52, no. 2 (May 30, 2019): 257–73. http://dx.doi.org/10.1177/1477153519853318.

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In this paper an iterative, closed-loop light control scheme is proposed and evaluated by a white light emitting diode-based, daylight-responsive luminaire to follow the time-varying pattern of correlated colour temperature and illuminance of a daylight scene. The proposed control scheme functions primarily with the response signals of two RGB colour sensors, viz., a daylight sensor to monitor the daylight scene at the window plane and an internal light sensor to monitor the light scene created by the test white light emitting diode luminaire. The control scheme controls the lumen delivery of individual light emitting diode arrays of the test luminaire by adjusting the duty cycles to follow the instantaneous correlated colour temperature of daylight and at the same time to respond to the variation of window plane illuminance in the reverse pattern. Evaluation is conducted by laboratory testing and in situ testing. The maximum deviations in correlated colour temperature, illuminance and chromaticity from the required values under laboratory testing and in situ testing are found to be [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text], [Formula: see text] respectively, which establish the acceptable performance of the proposed iterative light control scheme.

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Part, Chérie E., Phil Edwards, Shakoor Hajat, and Lisa M. Collins. "Prevalence rates of health and welfare conditions in broiler chickens change with weather in a temperate climate." Royal Society Open Science 3, no. 9 (September 2016): 160197. http://dx.doi.org/10.1098/rsos.160197.

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Climate change impact assessment and adaptation research in agriculture has focused primarily on crop production, with less known about the potential impacts on livestock. We investigated how the prevalence of health and welfare conditions in broiler (meat) chickens changes with weather (temperature, rainfall, air frost) in a temperate climate. Cases of 16 conditions were recorded at approved slaughterhouses in Great Britain. National prevalence rates and distribution mapping were based on data from more than 2.4 billion individuals, collected between January 2011 and December 2013. Analysis of temporal distribution and associations with national weather were based on monthly data from more than 6.8 billion individuals, collected between January 2003 and December 2013. Ascites, bruising/fractures, hepatitis and abnormal colour/fever were most common, at annual average rates of 29.95, 28.00, 23.76 and 22.29 per 10 000, respectively. Ascites and abnormal colour/fever demonstrated clear annual cycles, with higher rates in winter than in summer. Ascites prevalence correlated strongly with maximum temperature at 0 and −1 month lags. Abnormal colour/fever correlated strongly with temperature at 0 lag. Maximum temperatures of approximately 8°C and approximately 19°C marked the turning points of curve in a U-shaped relationship with mortality during transportation and lairage. Future climate change research on broilers should focus on preslaughter mortality.

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Shpak, S., V. Martirosova, T. Sakhno, and G. Kozhushko. "DIRECTIONS FOR IMPROVEMENT OF STANDARDS ON LED TECHNIQUE AND LIGHTING WITH ITS USE." Municipal economy of cities 1, no. 154 (April 3, 2020): 57–66. http://dx.doi.org/10.33042/2522-1809-2020-1-154-57-66.

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One of the main tasks of high-quality lighting is to provide comfortable visual work and adequate perception of illuminated objects by obtaining light with a wide range of correlated color temperatures with high color rendering quality. The paper analyzes the shortcomings of national regulatory documents on establishing tolerances for the color of lamps and fixtures using LEDs and evaluating their quality in color reproduction. Instead of using Mac Adam ellipses on the SIE 1931 (x, y) color chart for establishing the color requirements it is recommended to use circles on the 1976 SIE (u ', v'), and evaluate the color rendering quality using the CRI method, additionally apply the CQS and TM 30-18 methods. Due to the fact that the spatial color of LED luminaires can be inhomogeneous, it is recommended to indicate both the average color and color in a certain direction, as well as an indicator of the color heterogeneity. The necessity of developing standards for protection against unwanted non-visual biological effects, as well as other negative effects of artificial light, in particular, excessive brightness, pulsation of the light flux, photobiological hazards, etc., is substantiated. Considering the importance of the influence of light pulsation on the quality of lighting, before the development of CIE or IEC standards, it is recommended that national standards for LED lamps and luminaires include the requirements for description of pulsation parameters and measurement methods in accordance with the recommendations of IEEE 1789-2015 standard, which is the most advanced today. For the design of ergonomic lighting, it is proposed to provide information on lamps and luminaires related to their maximum brightness. When developing new criteria for lighting, taking into account the visual impact, it is already possible to use the knowledge accumulated by this time, in particular, for creation of biologically active and biologically dimmed light by changing the spectral composition of radiation and illumination. Proposals related to the limits of the correlated colour temperature, brightness, level of pulsation for lighting of children and educational institutions, residential premises and the like are also considered. Recommendations on the development of new national standards of Ukraine harmonized with international ones are also provided. Keywords: сolor rendering index, percent flicker, correlated colour temperature, illumination, photobiological safety

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Hrbac, Roman, Tomas Mlcak, Vaclav Kolar, and Tomas Vantuch. "Low-Cost Extra-Low Voltage LED Dimmer for Tuneable White Lighting." Elektronika ir Elektrotechnika 25, no. 3 (June 25, 2019): 43–49. http://dx.doi.org/10.5755/j01.eie.25.3.23675.

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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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Padmasali, AN, and SG Kini. "LED life prediction based on lumen depreciation and colour shift." Lighting Research & Technology 49, no. 1 (August 3, 2016): 84–99. http://dx.doi.org/10.1177/1477153515593580.

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Light emitting diodes, with advantages in energy savings, luminous efficacy and greater reliability, are becoming preferred over conventional white light sources. Currently, only light output depreciation is considered for life estimation of light emitting diode luminaires but it is recommended to include colour shift variations for applications demanding colour stability. In this paper, an extended Kalman filter is employed to determine L70 life and colour temperature degradation over life of a light emitting diode luminaire. The colour shift in terms of Duv is determined by statistical polynomial cure fitting. The variation in chromaticity coordinates over life is determined and life based on colour shift is determined by acceptable Duv limits. The results are compared to life determined by the IES-TM-21 method and the correlated colour temperature limits taken from the luminaire data sheet.

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Tonello, G., N. Hernández de Borsetti, H. Borsetti, L. Tereschuk, and S. López Zigarán. "Perceived well-being and light-reactive hormones: An exploratory study." Lighting Research & Technology 51, no. 2 (January 9, 2018): 184–205. http://dx.doi.org/10.1177/1477153517750714.

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Light can impact psychobiological processes in a healthy or harmful way, challenging designers to better understand the resources they are manipulating. The present exploratory study compared two forms of office lighting which differed in correlated colour temperatures and light level. A holistic approach, comprising visual, emotional and biological dimensions, was used to assess the lighting conditions that could favour productivity and well-being by means of the identification of congruent relationships between objective and subjective measurements in response to light stimuli. The former included analyses of melatonin and cortisol, and the latter were psychological instruments for measuring transitory mood, somnolence, and visual comfort. Controlled experiments were run in a laboratory with a repeated measures design, which yielded fifty-six evaluations. Although no extreme ranges of correlated colour temperatures were used in this study, the spectral blue component present in the correlated colour temperature of approximately 4000 K, and also provided by the light-emitting diodes system at a higher light level, could have contributed to render most of the strong effects on the inter and intra correlations among the psychobiological responses. The mediator role of the psychological profile of the individuals was demonstrated by the significant predictive value of the perceived stress measures.

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Abbott, Jessica K. "Morph-specific and sex-specific temperature effects on morphology in the colour polymorphic damselfly Ischnura elegans." Animal Biology 63, no. 2 (2013): 149–67. http://dx.doi.org/10.1163/15707563-00002402.

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Colour polymorphic species with extensive ranges often exhibit large-scale geographic patterns of morph frequency variation. Because colour polymorphism is associated with correlated differences in multiple traits, such as thermal performance, a likely proximate explanation for such patterns is morph-specific responses to temperature variation. The colour polymorphic Blue-tailed damselfly Ischnura elegans exhibits large-scale geographic variation in morph frequencies, but the possibility that temperature is a proximate explanation for the latitudinal cline in morph frequencies has only ever been tested within a single developmental stage (egg survival and hatching time), where no difference between the morphs was found. I therefore carried out a temperature manipulation on larvae of I. elegans which I raised to maturity in the laboratory. I found that individuals exhibited incomplete compensatory growth after being exposed to cold temperatures, and that individuals which did not emerge successfully and those that experienced cold temperatures had more juvenile morphology in the last instar. In addition, there were sex-specific and morph-specific effects of temperature on adult morphology, such that sexual size dimorphism was increased when individuals experienced warm temperatures throughout the larval stage, and that cold temperatures tended to result in larger size of androchromes and their offspring compared to the other morphs. These results are generally consistent with the large-scale geographic variation in morph frequencies found in this species.

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Wang, Yu, Qiang Liu, Wenyu Gao, Michael R. Pointer, Zheng Huang, Wei Chen, and Jiaxin Wu. "Interactive effect of illuminance and correlated colour temperature on colour preference and degree of white light sensation for Chinese observers." Optik 224 (December 2020): 165675. http://dx.doi.org/10.1016/j.ijleo.2020.165675.

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Huang, Zheng, Qiang Liu, Ying Liu, Michael R. Pointer, Peter Bodrogi, Tran Quoc Khanh, and Anqing Liu. "Gender Difference in Colour Preference of Lighting: A Pilot Study." Light & Engineering, no. 04-2020 (August 2020): 111–22. http://dx.doi.org/10.33383/2019-100.

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Gender difference has been widely reported in many research fields. However, in the topic of colour preference of lighting, such an issue has not aroused much attention. In this study, therefore, three groups of visual experiments with different illuminance (E) levels (50 lx, 200 lx, 600 lx) were conducted which investigated the preferred correlated colour temperature (CCT: 3500 K, 5000 K, 6500 K) for six single-coloured decorative artificial bird-shaped objects (red, green, yellow, blue, white and black). Twenty subjects, ten males and ten females, were invited to respond with their visual colour preference of the experimental objects. The aim of this work was to investigate if gender difference exists when the observers judge objects with different colours under different E-CCT conditions. The results indicate that there is significant difference between males and females for the 200 lx and 600 lx conditions, especially for the cases with higher CCTs (5000 K and 6500 K). In addition, it was found that under certain E-CCT conditions the preference ratings of males and females for certain colours were obviously different. Similarly, for some scenarios the subjective ratings from observers of the same gender also varied with object colour.

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Yurtseven, MB, S. Mete, and S. Onaygil. "The effects of temperature and driving current on the key parameters of commercially available, high-power, white LEDs." Lighting Research & Technology 48, no. 8 (August 3, 2016): 943–65. http://dx.doi.org/10.1177/1477153515576785.

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High-power LEDs with high luminous efficacies, compact sizes, long lifetimes and a wide colour range, are rapidly taking the place of conventional light sources in general lighting applications. But these properties of high-power LEDs are dependent on temperature and driving current. In this study, 24 samples of commercially available, high-power, white LEDs were measurement for their electrical, optical and thermal characteristics as well as their efficiency, luminous flux, luminous efficacy, correlated colour temperature and colour rendering index over six temperature steps at three different driving currents. LED manufacturers' catalogues including such information will allow consistency between the design and application stages of an installation. Also, it will make the technical and economic optimization of luminaires using high-power LEDs easier.

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Mills, Peter R., Susannah C. Tomkins, and Luc JM Schlangen. "The effect of high correlated colour temperature office lighting on employee wellbeing and work performance." Journal of Circadian Rhythms 5 (January 11, 2007): 2. http://dx.doi.org/10.1186/1740-3391-5-2.

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Suzer, Ozge Kumoglu, Nilgun Olgunturk, and Dilek Guvenc. "The effects of correlated colour temperature on wayfinding: A study in a virtual airport environment." Displays 51 (January 2018): 9–19. http://dx.doi.org/10.1016/j.displa.2018.01.003.

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He, J., Y. Lin, T. Yano, H. Noguchi, S. Yamaguchi, and Y. Matsubayashi. "Preference for appearance of Chinese complexion under different lighting." Lighting Research & Technology 49, no. 2 (August 3, 2016): 228–42. http://dx.doi.org/10.1177/1477153515615171.

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The method for evaluating the colour rendering of light-emitting diode sources is controversial, especially for the appearance of human complexions. A psychophysical experiment was conducted using Chinese models to examine the effect of various illumination settings, characterized by two levels of preferred skin colour index and four levels of correlated colour temperature, on preference for the appearance of the Chinese complexion. Results showed that the preferred skin colour index was an effective indicator. Taking incomplete colour adaptation into account, the preferred skin colour index was recalculated and shown to be the best colour rendering index for the appearance of the Chinese complexion. This research examined the concept of preferred skin colour index for Chinese women. This can supplement other colour quality evaluation methods, and shows promise for commercial lighting applications.

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Journal articles on the topic 'Correlated colour temperature'

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