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Objective: We investigate effects of the hue, saturation, and luminance of ceiling color on the perceived height of interior spaces.Background: Previous studies have reported that the perceived height of an interior space is influenced by the luminance of the ceiling, but not by the luminance contrast between ceiling and walls: brighter ceilings appeared higher than darker ceilings, irrespective of wall and floor luminance. However, these studies used solely achromatic colors. We report an experiment in which we extend these findings to effects of chromatic ceiling colors.Methods: We presented stereoscopic room simulations on a head-mounted display (Oculus Rift DK2) and varied hue (red, green, blue), saturation (low, high), and luminance (bright, dark) of the ceiling independently of each other.Results: We found the previously reported ceiling luminance effect to apply also to chromatic colors: subjects judged brighter ceilings to be higher than darker ceilings. The remaining color dimensions merely had a very small (hue) or virtually no effect (saturation) on perceived height.Conclusion: In order to maximize the perceived height of an interior space, we suggest painting the ceiling in the brightest possible color. The hue and saturation of the paint are only of minor importance.Application: The present study improves the empirical basis for interior design guidelines regarding effects of surface color on the perceived layout of interior spaces. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper describes an experiment to investigate discomfort glare caused by white light-emitting diode (LED) lights having different spectral power distributions. It included two groups: a ‘Metamerism’ group and a ‘correlated colour temperatures (CCT)’ group. In the former group, it was found that white lights at 7000 K constructed from different blue LEDs and the same red and green LEDs gave about the same glare perception. In the latter group, there was a significant difference in glare perception between white lights having different CCTs. Finally, glare models, including unified glare rating (UGR) and the newly derived QUGRspd, and mUGRspd models, were tested using the data from the experiment. All of them gave quite accurate predictions of the data. [ABSTRACT FROM AUTHOR]

Though several studies have reported human alertness to be affected by the intensity and spectral composition of ambient light, the mechanism behind this effect is still largely unclear, especially for daytime exposure. Alerting effects of nocturnal light exposure are correlated with melatonin suppression, but melatonin levels are generally low during the day. The aim of this study was to explore the alerting effect of light in the morning for different correlated colour temperature (CCT) values, as well as its interaction with ambient temperature. Body temperature and perceived comfort were included in the study as possible mediating factors. In a randomized crossover design, 16 healthy females participated in two sessions, once under 2700 K and once under 6500 K light (both 55 lx). Each session consisted of a baseline, a cool, a neutral and a warm thermal environment. Alertness as measured in a reaction time task was lower for the 6500 K exposure, while subjective sleepiness was not affected by CCT. Also, core body temperature was higher under 6500 K. Skin temperature parameters and perceived comfort were positively correlated with subjective sleepiness. Reaction time correlated with heat loss, but this association did not explain why the reaction time was improved for 2700 K. [ABSTRACT FROM AUTHOR]

What determines how languages categorize colors? We analyzed results of the World Color Survey (WCS) of 110 languages to show that despite gross differences across languages, communication of chromatic chips is always better for warm colors (yellows/reds) than cool colors (blues/greens). We present an analysis of color statistics in a large databank of natural images curated by human observers for salient objects and show that objects tend to have warm rather than cool colors. These results suggest that the cross-linguistic similarity in color-naming efficiency reflects colors of universal usefulness and provide an account of a principle (color use) that governs how color categories come about. We show that potential methodological issues with the WCS do not corrupt information-theoretic analyses, by collecting original data using two extreme versions of the color-naming task, in three groups: the Tsimane', a remote Amazonian hunter-gatherer isolate; Bolivian-Spanish speakers; and English speakers. These data also enabled us to test another prediction of the color-usefulness hypothesis: that differences in color categorization between languages are caused by differences in overall usefulness of color to a culture. In support, we found that color naming among Tsimane' had relatively low communicative efficiency, and the Tsimane' were less likely to use color terms when describing familiar objects. Color-naming among Tsimane' was boosted when naming artificially colored objects compared with natural objects, suggesting that industrialization promotes color usefulness. [ABSTRACT FROM AUTHOR]

This tutorial explains how the human perception of color rendering arises, in terms of the underlying phenomena of light and vision, and using those concepts it presents a clear explanation of the CIE Color Rendering Index. The strengths and weaknesses of the CIE Color Rendering Index are reviewed and some common misunderstandings about color rendering are addressed. It is suitable for self-study, with learning outcomes stated at the beginning and a conceptual summary provided at the end. [ABSTRACT FROM PUBLISHER]

In almost all color rendering calculations, where a reference illuminant is needed, a Planckian or daylight spectrum of the same correlated color temperature as that of the test source is used (a few methods tried to use only D65 or a very restricted number of test illuminants, but these have not received general acceptance). In this article, a new calculation method of color fidelity is introduced that uses modern colorimetric practice in order to reproduce the colors of the painting as seen under the light under which it was painted (probably daylight for a picture prepared before the end of the 19th Century) but keeping the correlated color temperature of the light source warm-white for museum lighting. The principles of corresponding color color rendering are described and an Excel workbook is provided for further testing purposes. [ABSTRACT FROM PUBLISHER]

Most descriptions of the color rendering properties of light sources are based on the calculation of color differences for a number of reflectance samples between the light source and a reference source. The CIE color rendering index (CRI) is a single number based on the average color difference for eight reflectance samples. Since its introduction, the CRI has been discussed at length and many alternatives have been suggested to improve the description of color rendering. These metrics comprise among others, metrics based on color fidelity, color gamut, and color preference and combinations of these. All of these new proposals try to capture a certain color rendering aspect in a single number index to be used instead of or together with the existing CIE CRI. The “traditional” CRI has been criticized due to the fact that a single number index does not provide sufficient information about the color rendering properties of light sources. Creating a (second) single number metric seems to be a bit of a paradox, because it suffers from the same limitation by providing an average number to characterize certain color aspects for all colors. In our view, the best way to provide users of lighting in whatever application with accurate information on color characteristics is to provide specific information on the most important color characteristics such as hue, chroma, and lightness. In this article, we describe our methods of supplying hue-specific information via color rendering vectors and color rendering icons. We illustrate why we believe that it is important to add hue-specific information and what the shortcomings are of a second hue-averaged metric. We acknowledge that color appearance models have advanced since our first calculations and that it would be more appropriate to use CIECAM02. In addition, several recent papers have appeared discussing improved reflectance sample sets. These advancements, however, do not change the key message in this article, which advocates the use of graphics to communicate shifts in hue and chroma. [ABSTRACT FROM PUBLISHER]

Limited data are available for comparing light-emitting diode (LED) bulbs that are currently available in commercial broiler production facilities. We evaluated the effects of color temperatures (kelvin) of LED bulbs on growth performance, carcass characteristics, and ocular development indices of broilers grown to heavy weights (>3.0 kg). The experiment had a randomized complete block design. Four treatments consisted of 3 LED light bulbs (2,700 [warm LED]; 5,000 [cool LED 1]; and 5,000 K [cool LED 2]) and incandescent light (2,010 K [ICD], standard) from day zero to 56 d of age. A total of 960 Ross × Ross 708 day-old chicks were equally and randomly distributed into 16 environmentally controlled rooms at 50% RH (30 males and 30 females/room). Thus, each of the 4 treatments was represented by 4 rooms (4 replicates) per trial. Feed and water were provided ad libitum. All birds were fed the same diet. Ocular specimens were collected on d 42 for development and histopathologic examination. Blood samples were collected on d 21, 28, 42, and 56 to determine plasma corticosterone. On d 56, twenty birds from each room (10 males and 10 females) were processed to determine weights and yields. The BW and BW gain (BWG), live weight, and carcass weights of birds reared under cool LED 1 were different in comparison to birds reared under ICD (P < 0.05). However, feed intake (FI), feed conversion ratio (FCR), and mortality were not affected by treatments. The treatments did not affect fat, breast and tender weights, and yields. In addition, ocular development indices and plasma corticosterone concentrations were not affected by treatments, suggesting the LED light bulbs we evaluated did not compromise the welfare of the birds. It was concluded that cool LED 1 may be a better potential replacement light source in comparison to ICD on performance, but it may be equal when compared to other LED light sources examined in this study. [ABSTRACT FROM PUBLISHER]

• High illuminance levels promote the purchase intention for both bread and cakes. • Bread and cakes are more appealing under low and high CCTs, respectively. • Wood-like background increases the purchase intention for bread under 3300 K. • Surprisingly, hunger status does not significantly affect the purchase intention. • For bread, male observers prefer wood-like background over white background. This study aimed to investigate whether the illuminance level and correlated colour temperature of light sources, as well as the viewing background, influenced the human visual assessment and purchase intention for bread and cakes. The impact of gender difference, hunger status and many other personal factors on consumption behaviour was also explored. Eighty participants, 40 males and 40 females, were asked to evaluate the appearance of bread and cakes against two different backgrounds under 15 light sources with different illuminance levels and correlated colour temperatures. The experimental results showed that illuminance level and correlated colour temperature had a significant effect on the colour appearance evaluation of bread and cakes. Bread was more suitable to be displayed under light sources with high illuminance levels and low correlated colour temperatures while cakes turned out to be more appealing under light sources with high illuminance and relatively higher correlated colour temperatures. In most cases, the impact of other potential factors, for example, the view background, hunger status and gender difference, turned out to be insignificant. Compared with a white background, a wood-like background significantly promoted the visual assessment of bread for male participants or assessed under light sources of 3300 K, but this impact was practically less meaningful than that of the lighting. The findings highlight the prominent influence of lighting for the display of baked products and provide empirical reference for people who expect attractive presentation of bread and cakes. [ABSTRACT FROM AUTHOR]

It is commonly believed that reddish colour induces warm feelings while bluish colour induces cold feelings. We, however, demonstrate an opposite effect when the temperature information is acquired by direct touch. Experiment 1 found that a red object, relative to a blue object, raises the lowest temperature required for an object to feel warm, indicating that a blue object is more likely to be judged as warm than a red object of the same physical temperature. Experiment 2 showed that hand colour also affects temperature judgment, with the direction of the effect opposite to object colours. This study provides the first demonstration that colour can modulate temperature judgments when the temperature information is acquired by direct touch. The effects apparently oppose the common conception of red-hot/blue-cold association. We interpret this phenomenon in terms of ''Anti-Bayesian'' integration, which suggests that the brain integrates direct temperature input with prior expectations about temperature relationship between object and hand in a way that emphasizes the contrast between the two. [ABSTRACT FROM AUTHOR]

Abstract It is essential to understand preferred skin colors for color reproduction in the display industry. This article presents three psychophysical experiments that were conducted to determine the preferred skin color ranges of East Asian women by East Asian observers on the chromatic and lightness components of CIELAB color space displayed on a standard sRGB-gamut display. In the first experiment, the preferred skin color was searched using various settings of correlated color temperatures (CCTs) and luminance levels on the screen. The results indicate that the most preferred skin color on a display had small differences between various images varying in CCT and luminance level. In the second experiment, a more precise preferred skin color center was produced. The preference scores were analyzed, and the preference map of skin colors was presented on the CIELAB a∗ b∗ plane. The final experiment examined the relationship between the lightness of facial skin color and the perceived preference on a display. It was conducted to examine the effect of the lightness component on the preference of facial skin color. It was found that the ( C a b ∗ , h a b ) value of the most preferred skin colors of East Asian women is (25.4, 50.5), with an L∗ value of 65. [ABSTRACT FROM AUTHOR]

This study develops look-ahead release planning on the basis of AutoMod simulation model validates with real data and experimentally investigates the impact of throughput. The significant factors of the experimental results show that look-ahead approach is effective in reducing idle time and improving throughput. [ABSTRACT FROM AUTHOR]

With advanced heating, ventilation, and air conditioning (HVAC) and colour tunable LED lighting systems, indoor environmental parameters can be precisely controlled. In most colour-tunable lighting systems, the colour of light can be easily changed without increasing energy consumption. Anecdotal evidence suggests that people are under the impression that reddish light creates the perception of a warmer environment than bluish light. Although several studies have been conducted, their findings have been inconsistent. Inside an office-like laboratory climate chamber at the University of Sydney, 45 subjects were immersed in nine thermal/lighting conditions - combinations of three different room temperatures (21 ± 0.3 °C, 24 ± 0.3 °C and 26 ± 0.3 °C) and three correlated colour temperatures (CCT – 2762 K, 3968 K and 6253 K). Using questionnaires, thermal sensation, thermal comfort, thermal satisfaction, and satisfaction with the lighting were evaluated both initially and after thermal and lighting adaptation. The results show that, in a warmer environment (26 °C), CCT impacts subjects' thermal sensation. Subjects judged the environment to be significantly cooler under 6253 K than 3968 K light (Z = −3.371, p = 0.001 for initial responses; Z = −3.173, p = 0.002 for adapted responses). Furthermore, high CCT light led to considerably improved thermal comfort at 24 °C and 26 °C. In a warmer environment (26 °C), 3968 K light positively impacted thermal comfort only after adaptation (Z = −2.883, p = 0.004 for 4000 K). The results also show that 2762 K light led to reduced satisfaction with the lighting for all temperature conditions. • 45 subjects were immersed in nine thermal/lighting conditions to investigate the hue heat hypothesis. • Scenarios included three different room temperatures and three correlated colour temperatures. • Subjects' thermal sensation is impacted by CCT only for warmer environments. • High CCT light led to considerably improved thermal comfort at 24 °C and 26 °C. • 2762 K light led to reduced satisfaction with the lighting regardless of different temperature conditions. [ABSTRACT FROM AUTHOR]