Color combination criteria in Le Corbusier's Purist architecture based on Salubra claviers from 1931

We have carried out a new study of the color combinations selected by Le Corbusier in ‘les claviers de couleurs’ for the Salubra wallpaper company in 1931, by analyzing them in the Natural Color System, which allows us to understand the perceptive variables of colors (hue, blackness, and chromaticness) as well as their combination criteria. Regarding the perceptive variables, we have discussed the selected hue ranges in relation to other color proposals of Le Corbusier himself, and we have shown the extensive presence of earthy hues, or the noteworthy absence of other colors such as yellows, violets, black, and white. We have also analyzed the chromaticness of colors, which is generally low, and the blackness, also very limited. In relation to the combination criteria, we aim to find out the underlying order in the color combinations by studying the similarities and contrasts of their perceptive variables. We demonstrate graphically, by a navigable three‐dimensional model, and with statistical support, some principles in Le Corbusier's color preferences, such as the combination of colors with equal chromaticness, the search of some contrast in blackness, or the usual resource of contrasting cool with warm colors, something slightly different to the contrast of complementary colors. We have also discussed other compositional criteria held by Le Corbusier to use color in his Purist architecture, which are related to the position and proportion of the surfaces to be colored, the connotations associated to different hues, or the use of plain colors, among others. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 85–100, 2016     

Preference for accent and background colors in interior architecture in terms of similarity/contrast of natural color system attributes

Color combination criteria are said to entail an affective response in interior design. We investigated the color combination criteria that orient the preference of current observers, after Le Corbusier's 1931 Salubra keyboards. We explored the similarity/contrast in Natural Color System (NCS) hue, blackness, and chromaticness in 312 combinations with four colors, two backgrounds and two accent colors, coming from 43 individual colors, on the walls of a simulated interior of a bedroom from the Swiss Pavilion (Le Corbusier, 1930-1931). Participants were 644 students of architecture and interior design in Western Europe and Near East, who evaluated with a Likert scale their preference for virtual images via an online survey. Results indicate that the most preferred color combinations are those with hues closer in the color wheel, being the similarity between hues in the backgrounds more important than in the accent colors, and with NCS B30G to G as the most preferred hues. Observers preferred color compositions with blackness under 10% and similar blackness between the two background colors, together with a certain blackness contrast between these background colors and the two color accents. Similarly, observers liked color compositions with low chromaticness and low chromaticness difference among the four colors of the composition.     

A comparative analysis of the characteristics and images of costume colors in the traditional plays of Korea,China, and Japan

The purpose of this study was to analyze quantitatively the characteristics and images of costume colors in the traditional plays of Korea, China, and Japan. The study focused on the Korean Masque, Beijing Opera, and Kabuki costume colors based on a selection of 1135 color samples. The collected source data were selected by extracting digital color data by using the Eyedropper Tool of Photoshop 7.0. The RGB color data were transformed to H V/C and the attributes of hue and tone were analyzed. Color images were analyzed with the color image scales of IRI Color Design Institute and Shigenobu Kobayashi to increase the validity of the evaluated images. As a result, the “five element colors (red, yellow, purple–blue (PB), white, and black)” from the theory of “Yin‐Yang Wu‐Xing” were used in the common stage costume colors of the Korean Masque, Beijing Opera, and Kabuki. Red, a preferred Asian color, was used most frequently in the costumes of these three traditional plays. A comparison of the traditional stage costume colors in the three northeast Asian countries revealed a difference in tones rather than in hues. First, the Korean Masque frequently used white in accordance with the tradition of white‐clad people and the cultural view of colors in which natural colors were preferred. Additionally, in the Masque, Koreans used colors based on the theory of Yin‐Yang Wu‐Xing with high‐chroma tones. On the other hand, the Beijing Opera exhibited the gorgeous and strong color images of China, by adopting high‐chroma colors in the Five Element Color: R, Y, PB, white, and black. Last, in the Kabuki costumes, a variety of white, black, dull, light, dark, strong, vivid, deep, bright, and grayish tones played an important role in showing various color images. The costume color images of the traditional plays of the three countries revealed that all shared the use of dynamic, springy/casual, and gorgeous images in the strong contrast of five element colors. Regarding the differences, the Korean Masque exhibited natural images in favor of natural colors, whereas the Kabuki displayed modern, decent/formal images by using dull, dark, and grayish colors. The study results suggested that the three countries commonly used five element colors from the theory of Yin‐Yang Wu‐Xing, but that their color images differed in terms of the tones used and the techniques for color combination. These results reflect that colors in the traditional costumes of the three countries are affected by their cultural codes, thereby representing the characteristics ofcertain peoples and cultural circles. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011     

Complementary colors theory of color vision: Physiology,color mixture,color constancy and color perception

I describe complementary colors' physiology and functional roles in color vision, in a three‐stage theory (receptor, opponent color, and complementary color stages). 40 specific roles include the complementary structuring of: S and L cones, opponent single cells, cardinal directions, hue cycle structure, hue constancy, trichromatic color mixture, additive/subtractive primaries, two unique hues, color mixture space, uniform hue difference, lightness‐, saturation‐, and wavelength/hue‐discrimination, spectral sensitivity, chromatic adaptation, metamerism, chromatic induction, Helson‐Judd effect, colored shadows, color rendering, warm‐cool colors, brilliance, color harmony, Aristotle's flight of colors, white‐black responsivity, Helmholtz‐Kohlrausch effect, rainbows/halos/glories, dichromatism, spectral‐sharpening, and trimodality of functions (RGB peaks, CMY troughs whose complementarism adapts functions to illuminant). The 40 specific roles fall into 3 general roles: color mixture, color constancy, and color perception. Complementarism evidently structures much of the visual process. Its physiology is evident in complementarism of cones, and opponent single cells in retina, LGN, and cortex. Genetics show our first cones were S and L, which are complementary in daylight D65, giving a standard white to aid chromatic adaptation. M cone later split from L to oppose the nonspectral (red and purple) hues mixed from S+L. Response curves and wavelength peaks of cones L, S, and (S+L), M, closely resemble, and lead to, those of opponent‐color chromatic responses y, b, and r, g, a bimodal system whose summation gives spectral‐sharpened trimodal complementarism (RGB peaks, CMY troughs). Spectral sharpening demands a post‐receptoral, post‐opponent‐colors location, hence a third stage. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011     

Experimental determination of laws of color harmony. Part 2: Harmony content of different monochrome color pairs

In 1956, we came to the decision at the Budapest Technical University to start large scale experiments on color harmony. The experiments and the processing of the experimental results have been completed in 2006, after 50 years of research work. The focal point of the experiments published in the current article has been the practical experience that the span of intervals between saturations and brightnesses of the compositions influence the harmony content of the composition, namely they determine in what extent we perceive the color composition as a harmonic one. Within the framework of experiments compositions have been shown to the participants, first those consisting of color pairs featuring the same hues and saturations but different brightnesses then those consisting of the same hues and brightnesses but different saturations. The method of experiments consisted of comparisons in pairs. There were 780 compositions prepared for the tests. The number of elementary observations during the tests comprised 544 000. It has been established that the variation of harmony content as a function of brightness‐ and saturation‐intervals could be described by a harmony function. It has been established that the variation of harmony content depending on brightness‐intervals is not, but that of depending on saturation intervals is being influenced by the hues of colors of the color pair in the composition. It has been established that in case of compositions with the maximum harmony content the interval of brightnesses of the colors making the color pair in each case gives d30V (d9Y), the interval of saturations gives d30T or is near to it. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 262–270, 2008.     

The versatility of color in contemporary architecture

In the 21st century, there has been a noticeable move toward the versatility of color in architecture. This can be attested to through an analysis of the color of buildings designed by some of the leading modern and contemporary architects, and a critical review of works written about the colors used in their buildings. This analysis goes on to identify four concepts related to the term versatility: transformation, fragmentation, movement, and novelty. These four concepts help us to understand the way color is conceived and arranged in contemporary architecture. By doing so, we aim to re‐establish the importance of color in the design of architecture, overcoming some former theoretical and practical preconceptions stemming from the modern era. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 344–355, 2013     

Practical color barrier‐free illumination for deuteranopia using LEDs

Here, we propose a color barrier‐free illumination consisting of white, red, and blue LEDs for people with deuteranopia‐type defects in color perception. Color perceptions of 20 volunteers with normal vision and four examinees of deuteranopia were evaluated by both the Ishihara test for color blindness and the Farnsworth Panel D‐15 test under color barrier‐free illumination. The illumination was comparably effective, not only for discriminating between red and green but also for discrimination of the hues on a color chip continuously. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 218–223, 2015     

Assessing the color of red wine like a taster's eye

Color of 33 commercial red wines and five‐color reference wines was measured in the same conditions in which visual color assessment is done by wine tasters. Measurements were performed in the two distinctive regions, center and rim, which are the regions assessed by wine tasters when the wine sampler is tilted. Commercial wines were classified into five color categories using the color specifications in their taste cards. The five color categories describe the spread of red hues found in red wines from the violet to brown nuances. The performance of CIELAB color coordinates in terms of their ability to reproduce the observed classification has been established using discriminant analysis. The CIELAB hue angle, h_ab, measured in the rim, where wine thickness is of the order of few millimeters, gives the best results classifying correctly 71.1% of the samples. Classification results are not significantly improved when additional color coordinates are considered. Moreover, ΔE* color differences with color reference wines do not provide good classification results. The analysis of reference and commercial wines supports the fact that hue is the main factor in the classification done by wine tasters. This is reinforced by the linear correlation found between h_ab in the rim and the wine age (R² = 0.795) in accordance with the fact that wines change their hues from violet to brown tints with ageing. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 153–162, 2009     

Experimental determination of laws of color harmony. Part 3: Harmony content of different hue pairs

At the Budapest University of Technology and Economics in 1956, we decided to start large‐scale experiments on color harmony. The experiments and the processing of the experimental data were completed in 2006. The experiments described in this article were based on a long established experience that harmony content of different hue pairs greatly differ from each other. The vast majority of former research activities on the subject of color harmony narrowed down mostly to investigations of saturated color pairs. Color samples of our experiments have been defined within the color space of the Coloroid color system, built on harmony thresholds. The compositions, prepared for the experiments, always consisted of two saturated hues and three low saturation colors of each hue at varying brightness, making it a total of eight colors. Within the framework of the experiments, 48 hues were used. Out of these, each of the 24 was formed into composition pairs with the remaining 48 hues, forming a total of 852 compositions. The paired‐comparison experiments were conducted with the use of the compositions prepared by collage technique. Color samples made of painted paper, between 1980 and 1985, have been repeated between 2002 and 2006 with the same color selection but with computer‐generated pseudorandom patch system compositions. It has been established that harmony content of hue pairs can be expressed by the relative angle of their hue planes in the Coloroid color space. The harmony content of hue pairs exceeds that of other pairs, when this angle is below 10°, between 30° and 40°, between 130° and 140° or near to 180°. Those color pairs of which hue planes are between 60° and 90° to each other in Coloroid color space, exhibit the least harmony content. © 2008 Wiley Periodicals, Inc. Col Res Appl, 34, 33–44, 2009.     

Unique hue judgments using saturated and desaturated Munsell samples under different light sources

Past studies investigating the unique hues only used samples with a relatively high saturation levels under standard illuminants. In this study, 10 observers selected the four samples with unique hues from 40 V6C8 (Value 6 Chroma 8) and 40 V8C4 (Value 8 Chroma 4) Munsell samples under six light sources, comprising three levels of D_uv (i.e., 0, ?0.02, and ?0.04) and two levels of correlated color temperature (i.e., 2700 and 3500 K). Significant differences were found between the two chroma levels for unique blue and yellow, with the hue angles of unique yellow and blue judged using the desaturated samples being significantly different from those defined in CIECAM02. The iso‐lines of unique yellow, blue, and green did not always go through the origin of the a*‐b* or a′‐b′ planes in CIELAB and CAM02‐UCS. Thus, the problems of CIECAM02, CIELAB, and CAM02‐UCS identified in this study need further investigations.     

Color constancy from invariant wavelength ratios: I. The empirical spectral mechanism

The wavelengths of several constant hues over four illuminants (D95, D65, D50, A) are derived from several sets of published data. In the plane of wavelength and reciprocal illuminant color temperature (MK^?1), the wavelengths of constant hues plot straight approximately parallel lines whose mean slope is about 87°. Parallel lines give invariant wavelength ratios, hence constant hues in this plane are near‐invariant wavelength ratios across illuminants. As recently demonstrated, the complementary wavelengths to a constant hue (across illuminants) represent the complementary constant hue; these complementary wavelengths also plot a near‐parallel line to the first constant hue. To confirm and further define the constant slope of these lines, it is shown that complementary wavelength pairs, per CIE data, can only plot parallel straight lines at the angle of 87° ± 1. In summary, near‐parallel sloping lines represent constant hues at near‐invariant wavelength ratios. This mechanism of color constancy is shown to relate to the well‐known theory of relational color constancy from invariant cone‐excitation ratios. In the visual process, the latter ratios are presumably the source of the former (invariant wavelength ratios). © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 238–249, 2008     

Experimental determination of laws of color harmony. Part 5: The harmony content of the various hue triads

We, in 1956 the Department of Architecture at the Budapest University of Technology and Economics, decided to start an extensive color harmony experiment. The experimental work, the collation, and processing of the collected data, lasting 50 years, was completed in 2006. The experiments described in this article are based on earlier experimental results obtained from investigation into the harmony content of hue pairs. We then decided to search for a third hue, which in association with an existing pair, with high‐color harmony, forms a hue triad with high‐harmony content too. The compositions prepared for the experiment were composed in each case of three hues of four identical saturation but different brightness, forming a group of 12 colors. The color content of the compositions covered the color space uniformly. That was the first stage in the experiment, carried out with 60 compositions. In the second stage, we investigated the effect of the saturation content of the colors used in the composition, on the harmony content of the hue triads. For this experiment, we prepared 48 compositions. In these experiments, we applied the method of grading. We concluded that the level of the harmony content of the hue triads depends on the inclination between the hue planes in the Coloroid color space. We also concluded that to every hue, selected for starting point, six well‐definable groups of hues can be ordered from the Coloroid color space, from which color triads with high harmony content, can be selected. It showed conclusively that the saturation level of the individual members of the triads has a significant influence on their harmony content. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2011     

Color names,stimulus color,and their subjective links

The aim of the research reported by this study was on the one hand to identify what colors were associated with particular words in relation to a specific language (Italian), by portraying them in color stimuli on the screen of a monitor; and on the other hand to verify whether some words of that language denoted colors that were either particularly well defined or confused with others. In an experiment using special software, the subjects were asked to produce colors directly, instead of choosing among a number of colors presented on the screen. The results showed that (i) it is possible to identify the color‐stimuli to which the terms of a language refer; that (ii) the “best” colors Giallo (Yellow), Rosso (Red), Blu (Blue), and Verde (Green) which the subjects were requested to produce were very similar to the corresponding unique hues; that (iii) among the mixed hues there were perceptually intermediate colors, that is, ones exactly midway between two consecutive unique colors: Arancione (Orange) and Viola (bluish Purple); that (iv) Turquoise and Lime were clearly positioned in the mental space of color of the participants; and that (v) for Italian speakers some hues coincide: Azzurro (Azure) and Celeste (Cerulean); Arancione (Orange), RossoGiallo (RedYellow) and Carota (Carrot); Lime and GialloVerde (YellowGreen), so that their color terms can be considered synonyms. Our most interesting finding, however, is that for Italian speakers these four mixed colors with their specific names (Lime, Turchese (Turquoise), Viola (bluish Purple) and Arancione (Orange) fall perceptually in the middle of each of the four quadrants formed in the hue circle by the four unique hues. The resulting circle is therefore characterized by eight colors of which four are unique and four are intermediate mixed. It would be advisable to repeat the study cross‐culturally to test for possible similarities and differences in color meanings with speakers of different languages. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 89–101, 2017     

White lighting: A provisional model for predicting perceived tint in “white” illumination

Recently, a line of minimum tint in chromaticity space for sources of illumination of different correlated color temperatures (CCTs) from 2700 K to 6500 K has been reported. This line of minimum tint did not correspond to the line of blackbody radiation implicitly associated with sources of white illumination used in architectural applications. It was noted that chromaticities along the line of minimum tint were not metamers but, rather, should represent, for a given CCT, chromaticities where the neural signals from the two spectral opponent channels were minimized. Earlier work provided a theoretical framework for representing the four unique hues where the neural signals from one spectral opponent channel are minimized. This framework was used here to quantitatively represent the line of minimum tint and then to empirically test whether this representation could predict the amount of tint perceived in six different sources of “white” Illumination.” Based on these results, a provisional model is proposed for describing the tint and the amount of tint perceived in “white” Illumination used in architectural applications. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 466–479, 2014     

Individual differences of unique hue loci and their relation to color preferences

Loci of the four unique hues (red, green, blue, and yellow) on the equiluminant plane on the color display and three preferred colors were obtained from 115 normal trichromats. We sought possible correlations between these measures. Different unique hue loci were not correlated with each other. The three preferred colors were not correlated with each other. We found five combinations of significant correlation between a preferred color and unique hue settings, yet the overall tendency is not very clear. We conclude that individual differences in color appearance measured by unique hues and color preferences measured by asking for favorite colors may not be predicted from each other or even within a category because the differences in the earlier visual mechanisms can be compensated for and these high‐level measures can be influenced by learning and experience. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 285–291, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20023     

Comparative studies on color preference in Japan and other Asian regions,with special emphasis on the preference for white

The results of three surveys are presented. The first survey was carried out in four large cities in Japan, and the findings were analyzed by factor analysis and cluster analysis. The second survey was carried out in Seoul, Korea and Tokyo, Japan to determine color preference in the two countries, focusing on the preference for white. The last survey compared color preference in Taipei and Tokyo, also with emphasis on the preference for white. In these successive studies on color preference in Japan and other Asian cities, the subjects were mainly asked to choose from a color chart the three colors they liked most and the three they liked least, and to state the reasons for their choices. The results of Survey 1 showed that color preference could be influenced by differences in age, sex, and geographical region. Also factor analysis and cluster analysis indicated some relation between color preference and the subjects' life styles. Dual scaling analysis of the results of Surveys 2 and 3 indicated that each Asian area has unique color preference tendencies and that there are statistically significant differences in the frequency of selection of colors of certain hues and tones. However, a high preference for white was common to all areas, along with preferences for some other colors. These results thus demonstrated a common strong preference for white in three neighboring Asian areas. The reasons given for the choices suggested that besides the factors of age and sex, associative images based on environmental and cultural aspects may be an important factor influencing color preference. © 1996 John Wiley & Sons, Inc.     

Optimal display color for nighttime smartphone users

The study investigated the optimal display color for comfortable use of smartphones at night under low illuminance, while not distorting the perceived quality of displays. Two phases of psychophysical experiments were conducted to judge perceptibility and acceptability of the displays in various shades of white. The experimental results showed that the scores in acceptability were always higher than those in perceptibility all across the hues, and yellow received the highest scores in acceptability among the six hue categories. This can be interpreted that the observers have the intention of using a display in a yellow shade of white even though it is not perceived as pure white. Through the analysis, a white in yellow shade with the RGB values of 255, 255, and 230 was determined as the optimal display color for nighttime smartphone users regardless of display luminance or contents. The proposed display color supports physiological comfort by reducing the blue light, which involves an adverse effect on the biological system, and provides psychological satisfaction by allowing users to decide the color within the range of the user's acceptable threshold. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 60–67, 2017     

Study of the color characteristics of residential buildings in Shanghai

In 2018, Shanghai launched a campaign to renovate the façade of old residential areas. With the renovation of the façade of these residential buildings, problems such as chaotic colors, dull colors, and strongly conflicting colors of walls have increasingly occurred. In this article, the color data of building samples were obtained by field investigation and the color attribute grading evaluation of residential buildings was carried out by introducing evaluation factors; thus, the evaluation results of these buildings were finally obtained. Based on the analysis of the quantity and proportion of each color attribute at different evaluation levels, the color characteristics of residential buildings in Shanghai were finally summarized. Overall, Shanghai residential buildings are “warm colored” in hue, “bright” in lightness, and “partial white” in chromaticness. The research results provide theoretical support for the forward‐looking and scientific nature of color planning for residential buildings in the future and can serve as a reference for the selection of the main colors of building walls.     

Calculation of color gamuts based on the Neugebauer model

The calculation of color gamuts is often based on transforming the colorant boundaries to color space. This method works for “well behaved” processes, but in some cases it is necessary to take into account not only these physical boundaries, but also other kinds of boundary surfaces. These additional boundaries are introduced here for 3-ink and 4-ink processes and are called natural and hybrid boundaries. Examples of print processes for which these different kinds of boundaries should be taken into account are given for the Neugebauer and localized Neugebauer model. Finally, an analytical approach is presented for the calculation of color gamuts of “well behaved” processes based on the Neugebauer model. © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 365–374, 1997     

Color composition in postmodern western architecture

This research aims to know some of the most innovative aspects of color in composition of postmodern architecture in Europe, approximately between 1960 and 2000. We describe the main chromatic trends in this period following historian JA. Ramírez's formal classification: the new utopias (‘60s), neo‐illuminist rationalism (‘70s), figurative postmodernity (‘80s), and deconstructivism (‘90s). For each trend, we point out some color composition features; analyze a case study building; and reflect on later influence on contemporary colored architecture. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 399–412, 2014