We propose a method for creating authenticable color images under UV excitation backlight by printing an invisible luminescent white emissive ink layer on the verso side of a transmissive substrate and a classical cmy image on the recto side of the substrate. In order to obtain a backlit image whose colors are as close as possible to the original image colors, we map the input image sRGB color gamut into the gamut formed by the emissive white source attenuated by the classical ink halftones. The relationship between surface coverages of the classical cmy ink halftones and the resulting backlit colors is obtained by accounting for the transmission of the emissive white through the paper substrate and through the classical cmy ink halftones. The transmittance of the classical ink halftones is modeled by a new halftone absorbance prediction model. The lightness range of the luminescent backlit color gamut is expanded by printing a black and white UV-absorbing instance of the original color image in superposition with the luminescent white emissive layer and in registration with the cmy image printed on the recto side. Luminescent backlit color images provide a high anticounterfeiting security, as they combine a verso printed invisible luminescent ink layer, a verso printed black and white instance of the original image and a matching recto printed cmy instance of the original image. The resulting luminescent backlit image colors are close to the original image colors only when observed in transmission mode under UV light. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

A total of six washed French and Algerian kaolins were studied. Kaolinite, halloysite, muscovite, feldspars, anatase, rutile, gibbsite, goethite, and todorokite were present. The thermal behavior of the samples was studied and the transformation heats were determined and quantified by differential thermal analysis. Calcined samples from 900°C to 1400°C are studied by X-ray diffraction, the results show that the crystallite sizes of mullite rises as the temperature rises. The calcined samples showed an inverse correlation of L* and the crystallite sizes of mullite due to the incorporation of chromophore elements (Fe³⁺, Ti⁴⁺, and Mn²⁺) in its structure. Muscovite and rutile phases decreased lightness and increased chromaticity. The reduction state of Fe³⁺/Fe²⁺ and Mn⁴⁺/Mn²⁺ at 1400°C enhanced lightness leading to the diminution of the b* parameter. The CIELAB color parameters were significantly affected with mineralogy and chemical compositions of the samples. Lightness of the natural kaolins is decreased (L* < 59) when organic matters beside manganese and iron oxides are present. L* was not affected when only iron (Fe²⁺) is present in the kaolin; however, the chromaticity is increased (b* > 22). Whiteness and tint indices (W₁₀, T_w,10) revealed that only one kaolin could be considered white (limits of CIE Colorimetry, 1986), though upon calcination, this number is enhanced to two. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

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, 2013

We investigated the relationship between mood and color according to musical preference. Volunteers were requested to select the mood evoked by music and the color associated with a mood word, and the color distributions and mood distributions were then analyzed with two-way ANOVA using Minitab. The results of the analysis indicated that mood and color were differently distributed, depending on the music genre presented and the musical preference of the listener. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

As light-emitting diode (LED) light sources mature, lighting designers will be able to deliver white light with a variety of spectral power distributions and a variety of color rendering properties. This experiment examined the effects of three spectral power distributions (SPDs) that were matched in illuminance and chromaticity on three measures of color perception: one objective (performance on the Farnsworth-Munsell 100 hue test) and two subjective (judgments of the attractiveness of one's own skin, and preferences for the saturation of printed images). The three SPDs were a quartz-halogen (QH) lamp and two LED sources that were matched to the QH lamp in terms of both illuminance and chromaticity; the three light sources were nominally CCT = 3500 K, x = 0.40, y = 0.39 and ∼ 400 lx. LED A used three channels (red, green, blue), and had very poor color rendering (R_a = 18). LED B used four channels (red, amber, cyan, white) and had very good color rendering (R_a = 96, whereas the QH had R_a = 98). Secondary hypotheses addressed the effects of age and skin and eye color on the dependent measures. As expected, LED A delivered very different color perceptions on all measures when compared to QH; LED B did not differ from QH. The results show that it is possible for LED sources to match the familiar incandescent sources. However, although it is possible to deliver what appear to be millions of colors with a three-chip (RGB) device, there is the risk of creating a very poor luminous environment. © 2013 National Research Council Canada and Wiley Periodicals, Inc. Col Res Appl, 2013

The relationship between the information the visual system gathers at its interface with the outside world and the perceptual reality of four primary hues and the resulting hue circle has been and remains of interest since the second half of the 19th century. Considerable effort has been expended over many decades in determining statistical mean choices of color stimuli that for individuals represent unique hues in given conditions of viewing. In this article, historical and recent data are used to show the present state of knowledge. To have a means of comparison, in this article spectral and display unit stimuli are converted to Munsell hues on basis of dominant or complementary wavelengths of highest chroma data. Relatively good agreement was found between spectral and color sample data, with display data being significantly different in case of unique green. The issue of significant interobserver variability found in all data and its implications are highlighted. Problems with generating simple psychophysical models, particularly related to unique red, are discussed and a brief survey of the current knowledge on neural processing that may lead to unique hue perception is presented. Data still required for a meaningful definition of mean unique hue stimulus data are listed. © 2013 Wiley Periodicals, Inc. Col Res Appl, 00, 000–000, 2013

A series of visual experiments were carried out to rate the similarity of color appearance of two color stimuli on categorical and continuous semantic rating scales. Pairs of color stimuli included two copies of the same colored real or artificial object illuminated by a test light source and a reference light source. A formula was developed to predict a category of color similarity (e.g., “moderate” or “good”) from an instrumentally measured color difference. Given a numeric value of a color difference between the two members of a pair of colors, for example, 2.07, the formula is able to predict a category of color similarity, for example, “good.” Because color-rendering indices are based on color differences, the formula could be applied to interpret the values of the new color-rendering index (n-CRI or CRI2012) in terms of such semantic categories. This semantic interpretation enables nonexpert users of light sources to understand the color-rendering properties of light sources and the differences on the numeric scale of the color-rendering index in terms of regular language. For example, a numeric value of 87 can be interpreted as “good.” © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

Previous attempts to predict chromatic-adaptation correspondence have led to a sharpening dilemma—i.e., Von Kries primaries are chosen that do not include in the positive octant all the realizable (x,y) chromaticities. This leads to paradoxical adaptation predictions for the colors that have negative Von Kries coordinates. A solution is proposed here that expresses the asymmetric-matching relation of chromatic adaptation as the product of two matrix transformations, given source illuminant 1 and destination illuminant 2: from source tristimulus values via adaptation matrix 1 to the adapted state coordinates, and from the adapted state via the inverse of adaptation matrix 2 to the destination illuminant tristimulus values. To avoid the sharpening instability, the entire spectrum locus must lie within the positive octant of the adapted state tristimulus space. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

Some familiar objects have a typical color, such as the yellow of a banana. The presence of such objects in a scene is a potential cue to the scene illumination, since the light reflected from them should on average be consistent with their typical surface reflectance. Although there are many studies on how the identity of an object affects how its color is perceived, little is known about whether the presence of a familiar object in a scene helps the visual system stabilize the color appearance of other objects with respect to changes in illumination. We used a successive color matching procedure in three experiments designed to address this question. Across the experiments we studied a total of six subjects (two in Experiment 1, three in Experiment 2, and four in Experiment 3) with partial overlap of subjects between experiments. We compared measured color constancy across conditions in which a familiar object cue to the illuminant was available with conditions in which such a cue was not present. Overall, our results do not reveal a reliable improvement in color constancy with the addition of a familiar object to a scene. An analysis of the experimental power of our data suggests that if there is such an effect, it is small: less than approximately a change of 0.09 in a constancy index where an absence of constancy corresponds to an index value of 0 and perfect constancy corresponds to an index value of 1. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

This study examined the role of color attributes (lightness and saturation) on children's color preferences for interior room colors. It also investigated children's most preferred colors among each of the five major hue families in the Munsell color system using scale-models. Previous color preference studies have typically been done with small color chips or papers, which are very different from seeing a color applied on wall surfaces. A simulation method allowed for investigating the value of color in real contexts and controlling confounding variables. Forty-five color samples were displayed on scale-models to 63 children ages 7–11 years old. This study identified children's most preferred colors among each of the five major hue families in Munsell color system. It also demonstrated that saturation was positively correlated with children's preferences in the red, green, blue, and purple hue families. In the yellow hue family, interestingly, lightness has a positive correlation with preferences. Children's gender differences were found in that girls prefer red and purple more than boys. These findings lead to color application guidelines for designers to understand better color and eventually to create improved environments for children and their families. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

In this study, we propose color images with color enhancement for congenital red–green color deficiency on the basis of the model proposed by Mochizuki et al. [In Terrassa, Spain: Proceedings for CGIV, Springfield VA: IS&T 2008;208–213] with the aim of facilitating color customization in displays used by color-deficient observers. Three types of color enhancements for deficiency were addressed in this study: colors were enhanced along the protan confusion line (i.e., P-enhancement), deutan confusion line (i.e., D-enhancement), and a line between the protan and deutan confusion lines (i.e., mix-enhancement). We investigated the color-enhanced image that is most preferred by each group of protan, deutan, and normal observers. Protan and deutan in this study indicate observers that are both dichromats and anomalous trichromats. Nine protan, nine deutan, and six normal observers participated in the experiment. The results showed that among the three types of color enhancements, the D-enhancement provided the best performance for protan observers. For deutan observers, all three types provided effective enhancement, although the P- and mix-enhancements were slightly better than the D-enhancement. Our results indicated that color enhancement increases the preference evaluations of protan and deutan observers. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

The early 17th century mural paintings set from the low-choir of the extinct Dominican Convent of Nossa Senhora da Saudação in the town of Montemor-o-novo were analyzed by a setup comprising visible spectra-colorimetry and scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS) complemented with optical microscopy (OM), micro X-ray diffraction, micro FTIR, and micro Raman spectroscopy. The main goals were material and diagnostic characterization of the paint layers and pictorial techniques used by Jose de Escovar workshop, one of the most active and controversial easel and mural painters of Evora Archiepiscopate between 1585 and 1622. The results show a differentiate use of red, blue, and green pigments in an alkaline environment. Stable mercury sulfide (HgS) was identified in almost all red areas in the latest scenes while, in the first ones, red ochre (Fe₂O₃) is the predominant pigment. Faded smalt (a co-potassium silicate glass) is present pure in the sky background or mixed with red ochre in the garments at the beginning of the low-choir but less at the end. Five kinds of copper-based materials, with different degrees of color alteration, were found, namely malachite and azurite, copper chlorides, copper sulfates (e.g., posjnakite), and pseudomalachite. Another curious feature is the uneven use of a limewash made with slaked calcitic lime in the carnations. Lack of material, internal organization strategies, or technical differences within the team are probably the most likely causes. © 2013 Wiley Periodicals, Inc. Col Res Appl, 00, 000–000, 2013

Subjective colour spaces were reconstructed for persons occupationally exposed to mercury (Hg) and patients with diabetes mellitus type 2, two groups at risk for acquired colour-vision deficiency, and compared with healthy normal trichromats. Judgments of colour dissimilarity were collected with the method of triads, applied to a composite assortment of colour samples. These were drawn from two widely used colour arrangement tests—10 hues from the Farnsworth D-15 test and five from the Lanthony Desaturated D-15d test, ensuring that the assortment sampled two levels of lightness and saturation. The data were analyzed with maximum-likelihood multidimensional scaling (MDS) and within a novel individual-differences MDS model to estimate subject-specific parameters. The MDS solutions for the two clinical groups showed a compression along a blue-yellow axis, limited however to desaturated hues. This result was confirmed by the individual-differences model. In addition, the clinical groups were found to place significantly higher weights on the lightness differences between stimuli, conceivably to compensate for their reduced chromatic discrimination. The specific form of colour-space distortion in the clinical groups indicated an increase in their thresholds for blue-yellow signals, providing insights into the nature of impairment mechanisms. The results have implications for stimuli and diagnostic procedures for testing individual differences in color vision, and for analyzing the responses. This approach is sensitive to distinctive patterns of subtle colour-vision impairment underestimated by the conventional D-15d test. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

In a recent note, Brill and Carter propose to revisit the centuries-old disagreement over the relationship between stimuli and perceived lightness or brightness and the mathematical model that best represents it. Here, the answer is offered that the only way to resolve this matter is empirically, with controlled experiments of different kinds that establish statistically meaningful and replicated data for a given set of test conditions and methodology. Given the fact that surround lightness has a very significant effect on the results, including the crispening effect, a model can only be valid for a limited set of conditions, and the likely outcome is multiple models or models with multiple variables. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013

This study investigated how color stimuli that consisted of green foliage plants (Epipremnum aureum) with same sized area of Kalanchoe spp. plants with four different flower colors (white, yellow, pink, and red; Kalanchoe spp.) on a dark green background influenced the brain waves and emotions of 30 undergraduate students. Electroencephalography tests were performed in order to monitor the brain-wave responses in the prefrontal, frontal, parietal, and occipital lobes in response to the different plant color stimuli. Fourteen pairs of adjectives on the semantic differential scale were used to measure emotional changes. A statistical analysis showed that all of the color stimuli correlated with some emotional keywords and physiological responses. Green plants (E. aureum) produced more positive attitudes, and brain functions were more active compared to those observed after the participants were exposed to white, yellow, pink, or red flowers on a green background. In addition, when participants looked at the green plants, the relative fast alpha power spectrum increased, indicating the involvement of improved concentration, creativity, and attention. However, optical stimuli from the yellow flowers had a positive effect on the parietal and occipital lobes, producing a high relative theta power spectrum and indicating that concentration was improved and that the subjects were happier. The choice of adjectives and the EEG patterns were weakly but significantly correlated. These results may have practical applications because green plants can be used in places where comfort and high concentration are required, plants with white and yellow flowers can be used to make a place more pleasant, and red flowering plants can be used to create a luxurious environment. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

Dichromatic colour vision is commonly believed to be a reduced form of trichromatic colour vision (referred to as the reductionist principle). In particular, the colour palette of the dichromats is believed to be a part of the colour palette of the trichromats. As the light-colour palette differs from the object-colour palette, the dichromatic colour palettes have been derived separately for light-colours and object-colours in this report. As to light-colours, the results are in line with the widely accepted view that the dichromatic colour palettes contain only two hues. However, the dichromatic object-colour palettes have proved to contain the same six component colours which constitute the trichromatic object-colour palette (yellow, blue, red, green, black and white). Moreover, all the binary and tertiary combinations of the six component colours present in the trichromatic object-colour palette also occur in the dichromatic object-colour palettes. Yet, only five of the six component colours are experienced by dichromats as unitary (unique) object-colours. The green unitary colour is absent in the dichromatic object-colour palettes. The difference between the dichromatic and trichromatic object-colour palettes arises from the fact that not every combination of the component-colour magnitudes occurs in the dichromatic object-colour palettes. For instance, in the dichromatic object-colour palettes there is no colour with the strong green component colour. Furthermore, each achromatic (black or white) component colour of a particular magnitude is combined with the only combination of the chromatic components. In other words, the achromatic component colours are bound with the chromatic component combinations in dichromats. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

To provide camouflage in near infrared (NIR) region and imitate reflectance profile of greenish leaves, cotton fabrics were dyed with three selected vat dyes, namely C.I. Vat Blue 6, C.I. Vat Yellow 2, and C.I. Vat Red 13. Reflectance curves of two types of fresh greenish leaves were measured as standard reference. Transmittance curve of vat dyes in acetone solution indicated that selected vat dyes have suitable structure to provide camouflage in NIR region. According to reflectance profiles, reflectance curve of Vat Blue 6 has more similarity with that of green leaf at the concentration of 0.85% owf (on weight of fiber) and 1.2% owf in comparison with those of C.I. Vat Yellow 2 and C.I. Vat Red 13. Cotton fabrics were dyed with different mixtures of the dyes to obtain a standard shade to reach camouflage in visible range. Chromatic values of dyed fabrics were measured (CIE1976 L*, a*, and b*) and two standard shades of the 1948 US army pattern, NATO and forest green, were obtained on cotton fabrics with ΔE_CMC < 2. Reflectance profiles of these two shades were located between the reflectance of green leaves. So, two vat dyes were introduced to camouflage dyes group, C.I. Vat Blue 6 and C.I. Vat Red 13, and used to achieve NATO green and forest green shades for first time. All dyed samples showed good fastness properties. The effect of washing and light exposure on camouflage properties of fabrics in visible and NIR region was inconsiderable. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

We agree with the main point of Rolf Kuehni's letter; time is ripe to improve the standard lightness metric L*. We discuss items he raised: scientific literature supporting both log and power laws of lightness, the relation of math theory and curve fitting, crispening, different models of lightness for different situations, and “who cares?” © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012.

Preferred chroma enhancement and its dependence on hue are studied in a two-part experiment using a wide-gamut multiprimary display. Earlier research showed a clear dependence on hue but was limited by the gamut of the display it employed; the present work builds on this while easing the gamut constraints. In the first part of the present experiment, a tuning task was used to refine the preference for chroma boost starting with standard-gamut (Rec. 709) images. The overall median preferred boost is roughly 20%, but it is not uniform over hues: the preferred boost for orange, yellow, green, and cyan colors is greater than that for blue, magenta, and red colors. Dependence on image content and observer is noted, though a content-independent chroma boost created by aggregating preference over many images performs well. An adjustment parameter for overall chroma, which incorporates the hue dependence averaged over image content, should be sufficient to handle the vast majority of interobserver variance in preference. In the second part of the experiment, various chroma boost algorithms were evaluated through a paired comparison task. The prescribed hue-dependent chroma boost is preferred over all other variations, and all hue-preserving chroma boost variations are preferred over both colorimetrically accurate and naı¨ve same-drive-signal renderings. The results may be applied in display design to select gamut boundaries that maximize satisfaction over the observer population. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

The Canonical Biplot method is used to determine the magnitude of the effects on the Δ chromatic coordinates (ΔL*, Δa*, Δb*) and the parameter ΔE*, where (ΔL*, Δa*, Δb*) are the difference in the values of the sample after each aging cycle and the value of the untreated sample and ΔE* = [(ΔL*)² + (Δa*)² + (Δb*)²]^1/2. We performed a study of the changes in color produced by two types of artificial aging procedures on four varieties of siliceous conglomerates from Zamora (Spain) that have traditionally been used in construction and later renovations in historical buildings in the zone. To accomplish this, 25 cycles of the following types of accelerated artificial aging were carried out: (a) freezing/thawing and cooling/heating (T1) and (b) combined freezing/thawing and cooling/heating + salt (phosphates) crystallization (T2).

The results of the statistical study applied (Canonical Biplot) allowed us to differentiate the magnitude effect on the color of the surface brought about by T1 as compared with T2. These effects (p < 0.05) were observed in all but one (ochre conglomerate) of the varieties, but mainly in the variable governing red hue (Δa*) and yellow hue (Δb*). © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

The dichotomy between the logarithmic and power-law models of lightness perception is revisited. Both laws (and no other) are permitted by the luminance scale-invariance of the equality of lightness differences. The logarithmic law, which emerges out of integration of Weber's law for just-noticeable differences (JNDs), is the only one of these that is compatible with the observed background-lightness-invariance of the lowest JND and also with the additivity of JNDs. The power law, although defensible as a fit to empirical data, is not compatible with JND additivity. Both laws must be compromised in form to fit other mathematical necessities (e.g., continuity and domain), hence the remaining question is: can JNDs be summed to total lightness. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

The principal component analysis technique is used for the compression of different spectral databases including the reflectance spectra of nonfluorescent surfaces as well as the spiky spectra of the total radiance factors of fluorescent samples. Before extraction of principal directions, the Box-Cox transformation technique is used in its original as well as modified version to improve the efficiency of employed compression technique by increasing the degree of normality in the datasets. The employed techniques are evaluated in terms of spectral dissimilarity between the reconstructed and the actual spectra and colorimetric differences by the value of CIELAB color differences of them under D65 and A illuminants and 1964 standard observer. The datasets departures from normal distribution are also investigated. The results confirm the effectiveness of the Box-Cox modification technique for the reducing of spectral dimensions of samples. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

Illuminant chromaticity estimation is required in the fields of the tracking and recognition of human faces, compensation and detection of skin color, image reproduction, and color constancy. This article proposes a simple and effective method to estimate the illuminant chromaticity using highlights from the face region. We first select the candidate points through the detection of highlights around the leftmost pixel of the rg chromaticity space from the facial images under various illuminant conditions and then estimate the illuminant chromaticity by averaging the chromaticities of the candidate points. To enhance the illuminant chromaticity estimation accuracy, we propose a more elaborate estimation method, which effectively readjusts the candidate points of the highlight regions according to the conditions derived from two ethnic and three illuminant groups. The experiment results show that our proposed method reliably estimates the illuminant chromaticity under various color temperatures and illuminant directions. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

In the highly competitive display market, manufacturers continuously develop new technologies to improve the image quality of displays. However, color measurement and visual assessment are time-consuming to production lines. A new method to measure and improve color quality of the displays automatically therefore, is urgently needed to the manufacturers. This article proposes a familiar color correction strategy to optimize the colors of different displays by means of creating an image-based color palette which enables color correction for familiar objects (e.g., facial skin, blue sky, or green grass) in the multidisplay systems. To produce the image-based color palette, the 8-bit RGB value of each pixel in an image is transformed to L*d*n* (lightness/dominant color/nondominant color) color channels, and the dominant-color regions in an image are subsequently extracted from the dominant color (d*) channel. The memory color data of familiar objects can be set in reference monitor in advance to determine the dominant color (d*) channel. Then a series of palette colors are generated around a displayed image. The color palette will be displayed as a target for two-dimensional colorimeter shooting to obtain the measured color data. The familiar color correction model was established based on a first-order polynomial regression to achieve a polynomial fit between the measured color data and the reference color data on the color palette. The proposed method provides a solution to correct familiar colors on a displayed image, and maintains the original color gamut and tone characteristic in the multidisplay systems simultaneously. It is possible to achieve the preferred intent of the displayed images by using the proposed familiar color correction method. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

Glass color may influence the evaluation of food and beverages as has been reported in a previous study where participants rated a cold beverage presented in a blue glass to be more thirst-quenching than the same beverage poured into a green, yellow, or red glass. Our experiment sought to test whether container color also can affect the perceived temperature of a warm beverage. One hundred and twenty undergraduates were given warm coffee served in cups of different colors (blue, green, yellow, and red) and were asked to indicate which beverage was the warmest. Statistically significant differences among colors were found. The red cup was evaluated as containing the warmest beverage (38.3%), followed by the yellow (28.3%), the green (20.0%), and the blue (13.3%) cups. Conventional associations between warm versus cool colors are used to explain these results. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

We present an interactive visualization tool for generating color schemes that can be used by both professional artists and novice designers to improve their design efficiency. The method is developed on two color harmony principles of familial factors and rhythmic spans from conventional color theories. The interactive tool makes use of these principles for users to interactively generate colors palettes containing harmonious combinations in the hue, saturation, and lightness color space in as few steps as possible. A pilot study with 20 participants has shown that this tool provides efficient workflow, color-scheme harmony, and intuitive interaction, demonstrating the usefulness of the method. This work contributes to an artistic-theory driven harmonious color-scheme generation and to interactive user interfaces visualizing color relationships. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

An object colour's Commission Internationale de l'Éclairage XYZ coordinates can change when it is viewed under different illuminants. The set of XYZ coordinates for all object colours, which is called the object-colour solid, likewise varies under different illuminants. This article shows that, despite these changes, some properties are invariant under illuminant transformations. In particular, as long as the illuminant is nowhere zero in the visible spectrum, optimal colours take the same Schrödinger form, and no two optimal colours are metameric. Furthermore, all object-colour solids have the same shape at the origin: they all fit perfectly into the convex cone (which we will call the spectrum cone) generated by the spectrum locus. The spectrum cone, itself, does not vary when the illuminant changes. The object-colour solid for one illuminant can be transformed into the solid for another illuminant, by an easily visualized sequence of expansions and contractions of irregular rings, called zones. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

We have analyzed the performance of simulated multispectral systems for the spectral recovery of reflectance of printer inks from camera responses, including noise. To estimate reflectance we compared the performance of four algorithms which were not comparatively tested using the same data sets before. The criteria for selection of the algorithms were robustness against noise, amount of data needed as inputs (training set, spectral responsivities) and lacking of use of dimensionality reduction techniques. Three different sensor sets and training sets were used. We analyzed the differences in the spanning of the subspaces found for the three training sets, concluding that the ink reflectances have characteristic features. The best performance was obtained using the kernel and the radial basis function neural-net-based algorithms for the training set composed of printer inks reflectances, whereas for the other two training sets (composed of samples from the ColorChecker DC and Vhrel's reflectances' set) the quality of the recovered samples was more uniform among the algorithms. We also have performed an optimization to choose the best sensor set for the multispectral system with a reduced number of sensors. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

Seven flower colors perceived by five color experts using visual color measurement under 2800 K warm white fluorescent lamps, 3500 K plant growth lamps, and 6500 K light-emitting diodes (LEDs) were compared with those under 6500 K fluorescent lamps, which represented illuminants in florist shops. Fluorescent lamps (6500 K, 1000 lx) were found to be effective for displaying flower colors and were used as the standard condition. The colors of flowers generally shifted in the same direction as those of the illuminants in CIELAB space. The color differences were highest under the 3500 K fluorescent lamp at both 500 and 2000 lx. At 500 lx, the ΔE values under the 6500 K LED were higher than those under the 2800 K lamp. The C* and ΔE values revealed that the 2800 K lamp was unsatisfactory for purple-blue and purple flowers and was more suitable for floral displays at lower illuminance. Under the 3500 K lamp, the highest color distortion occurred in cool-colored flowers, but C* increased for purple-blue and purple flowers. The 6500 K LED tended to decrease C* for warm-colored flowers under both illuminances, but it was effective for displaying purple-blue and purple flowers with increased C*. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

In the automotive industry, color quality control is increasingly done by reflection measurements. We discuss how color tolerances are set in specifications to suppliers of add-on parts and to paint suppliers. We mention several factors that often lead to unrealistically tight settings, and therefore to incorrect rejections and unnecessary high productions costs. We show that this is likely to occur when the dE_ab color difference equation is used, or when a strict criterion separating pass from fail is used instead of specifying a “grey area” where instrumental monitoring needs to be followed by visual assessments. Unrealistically, tight tolerances also result from halving tolerances in the supply-customer chain in an attempt to compensate color variations due to uncontrolled application conditions. Tolerances should be widened further when a gap separates an add-on part from the car body, making visual discrimination of color differences less critical. Other common situations where tolerances should be widened are the presence of visual texture in effect coatings, the lightness of metallic coatings becoming very high (L*> 100) and measurement geometries close to the gloss angle. Finally, we address the issue that instrumental color tolerances should not be tighter than what is allowed by instrumental reproducibility, repeatability, and inter-instrument agreement. Accounting for these factors, we provide a set of reasonable values for tolerances on color and on visual texture parameters, based on our own practical experience. But realistic tolerance values depend very much on actual conditions, and should be agreed in tripartite discussions among automotive industry, suppliers of add-on parts, and paint supplier. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

Reactive dye fixation and color yield of a dyed cellulosic fiber significantly depend on the dye diffusion into the fiber polymer system. In case of pad-dyeing processes, dye diffusion exerts a more significant influence on dye fixation and hence color yield. This article proposes a new method for determining the extent of diffusion of reactive dyes into the fiber in pad dyeings using Kubelka–Munk equation. The K/S values are used as in an equation, %D (extent of dye diffusion) = 100 − [(K/S_{diffusion index})/ (K/S_reference) × 100]. The article introduces and explains how to determine the new K/S variables used in this equation. The new method is simple, nondestructive, relatively faster, and applicable to industrial dyehouses, and was validated by a microscopic analysis of dyed fiber cross-section carried out in this work and to the dye manufacturer's recommendations for dyebath-ingredient concentrations. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

CIECAM02 has been used to predict colour appearance under a wide range of viewing conditions, to provide a uniform colour space, and to provide a profile connection space for colour management. However, some problems have been identified with CIECAM02. CIE Technical Committee 8-11 is currently working on the methods to resolve the problems for practical applications. Part of the CIE TC8-11 work is to repair the lightness computational failure. This article incorporates most of the previous suggestions and makes some further tests. It is hoped that this article will aid the ongoing work of the CIE TC8-11 and perhaps be the starting point for repairing the CIECAM02 for colour management and for the new recommendation. © 2012 Wiley Periodicals, Inc.

Complexities on the roles of reference color gray and grayness are reviewed. They are essential in color appearance, but gray is an implicit color. Although “grayness” is not explicitly used in visual color assessment of surface colors or color order systems, gray can be combined with any colors having six primary-color components using the term “grayish,” for example, grayish red and grayish yellow. However, the existing region of grayness is limited in a part of color-appearance space. Illuminance dependency of gray perception is also clarified. Existence of two kinds of psychometric quantities are suggested: one is the attribute of grayness based on its psychological amount in a grayish color under study, and the other is the attribute of brightness of the grayish color under a specified illuminance, psychophysical quantity. The Nayatani-Theoretical color order system, which uses three opponent-colors axes, can clarify the above complexities of gray and grayness. Its importance is the same as six primary colors, red–green, yellow–blue, and white–black. © 2012 Wiley Periodicals, Inc.

In this article, we investigate how context influences color preferences by comparing preferences for “contextless” colored squares with preferences for colors of a variety of objects (e.g., walls, couches, and T-shirts). In experiment 1, we find that hue preferences for contextless squares generalize relatively well to hue preferences for imagined objects, with the substantial differences being in the saturation and lightness dimensions. In experiments 2 and 3, we find that object color preferences are relatively invariant when the objects are (a) imagined to be the color that is presented as a small square, (b) depicted as colored images of objects, and (c) viewed as actual physical objects. In experiment 4, we investigate the possibility that object color preferences are related to the degree to which colors help objects fulfill particular functions or outcomes. We also discuss relations between our results and previous theories of color preference. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

Making an artificial iris with an aesthetically acceptable color is an important aspect of ocular rehabilitation. This work evaluated the influence of different disinfecting solutions on changes to the color of artificial irises used in ocular prostheses. Fifty samples simulating ocular prostheses were produced with cobalt blue artificial irises and divided (n = 10) according to the disinfectant used: neutral soap, Opti-free, Efferdent, 1% hypochlorite, and 4% chlorhexidine. The samples were disinfected for 120 days and subjected to a color readings by spectrophotometry, using the CIE L*a*b* system, before the disinfection period (B), after 60 days of disinfectant exposure (T₁), and after 120 days of disinfectant exposure (T₂). Color differences (ΔE) were calculated for the intervals between T₁ and B (T₁B), and between T₂ and B (T₂B). The data were evaluated by analysis of variance and the Tukey Honestly Significantly Different (α = 0.05). All disinfectant groups exhibited color changes. The mean color change observed for all groups overall during T₂B (ΔE = 3.51) was significantly greater than that observed during T₁B (ΔE = 2.10). All groups exhibited greater color change for the b* values when compared to the a* and L* values. There were no significant differences between the disinfectant groups. It can be concluded that the time period of disinfection and storage significantly affected the stability of artificial iris color, independent of the disinfectant used. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012.

This article aims to identify the essential components of the luminosity of skin coated with powder foundation, based on two processes: reflection measurement and visual evaluation of the skin surface. The luminosity refers to the state of being “luminous,” “brilliant,” or “radiant” of the foundation-coated skin. First, a flat piece of artificial skin is used, and an experimental device is developed to visually evaluate the appearance of the foundation-coated artificial skin at different conditions of viewing angle, illumination angle, and illumination intensity. The luminosity score is analyzed from the point of view of optical reflection. Next, the same assessment of luminosity is executed for real human skin. The luminosity is evaluated for cheek and forehead coated with powder foundation at different observation conditions using another experimental device. Finally, all luminosity scores are analyzed in color spaces to identify the color region relating to luminosity perception. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012.

Within the framework of our series of experiments, 16 artists made judgments on the harmony content of color compositions using two different methods. First, using the traditionally accepted method, at natural daylight, with their eyes adapted to light, they judged the compositions. Following that, they used, the nowadays more popular, instrumental simulation of the experimental color objects. The second part of the experiment was performed in a dark room and the subjects had their eyes adapted to dark, before the experiment. According to the outcome of these experiments, the results were substantially different. These differences were recorded in diagrams and formulated in mathematical form. Our conclusion, based on these results, is that the simulated experimental results cannot be used for the description of the harmony content between colors at natural conditions. The importance of these results has strong relevance to the judgment of color harmony between colors on the TV screen. To describe this particular harmony, we need a different word. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012.

A set of 10 color pairs was proposed and produced in 2002 to show the advantages of the CIEDE2000 color-difference formula with respect to CIELAB. These 10 color pairs illustrated each of the five corrections to CIELAB proposed by CIEDE2000. The 10 color pairs were visually assessed, under reference conditions close to those proposed by CIEDE2000, by two groups of 31 and 21 inexperienced observers, using two different gray scales. Average visual results in these experiments fitted CIEDE2000 predictions much better than CIELAB, as shown by a decrease of Standardized Residual Sum of Squares values of about 20 units. Current visual results showed only the improvement of CIEDE2000 upon CIELAB in predictions of perceived color differences, but they are not recommended for testing new advanced color-difference formulas. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012.

The impurity transition element chromium Cr³⁺ in ruby can be excited to high energy levels by absorbing visible light. When the excited Cr³⁺ returns to ground state through an intermediate energy level, the ruby emits red light as fluorescence. The fluorescence of ruby is actually caused by visible light, not by ultraviolet. The color of ruby is attributed to both the absorption and the fluorescence. The spectrum of a natural ruby under visible light is directly measured by a dual integrating sphere spectrometer. The measured spectrum includes both the spectral reflectance and the fluorescence caused by visible light. This study confirmed that the red fluorescence of ruby is indeed caused by visible light, not by ultraviolet radiation. In addition, average color of the ruby is calculated from the measured spectrum, and true color grade is also obtained by the artificial intelligent software of the spectrometer. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012.

CIE Division 1 entrusted TC 1–74 to investigate the possibility to develop a smooth curve version of the D illuminants. This article investigates the possibility to create such smoothed curves with minimal colorimetric error. Six different smoothing algorithms were investigated; the best method, using a locally weighted regression and smoothing algorithm, enabled a smooth function, where the worst colour difference for a 100 000 sample set was less than ΔE_ab * = 0.5, comparing calculations using the CIE standard daylight spectrum and the smoothed function. Thus, the smoothed function can be recommended for redefining the daylight spectra for colorimetry without loosing continuity to results using the current calculation tables and for designing daylight simulator spectra. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012.

Although black is an important color, the perception of black objects has not been systematically examined. The purpose of this work was to determine the influence of hue on the perception of preferred blackness. A set of 20 glossy low chroma Munsell sheets were purchased comprising a complete hue circle with a value and chroma of two and one, respectively (L* = 19.3–20.75, and C* = 3.66–6.58). The Munsell samples were divided into two interleaved groups: (5R, 5YR, 5Y, 5GY, 5G, 5BG, 5B, 5PB, 5P, and 5RP) and (10R, 10YR, 10Y, 10GY, 10G, 10BG, 10B, 10PB, 10P, and 10RP). Fifty color-normal observers force-ranked the two sets of 10 samples from “most like black” to “least like black.” Observers then assessed a set of six samples that represented the three samples from each set of 10 that the observer chose to be “most like black.” The 50 observers were found to have fairly good autoconcordance and concordance values. In repeat experiments observers agreed with themselves in 81% of the pairwise decisions, and they agreed with the grand mean rank 76% of the time. The blue–green samples (with Munsell hue notations 10G, 5BG, and 10BG) were most selected (and were considered blackest), followed by green, blue, and purple–blue. The samples selected the fewest times by any observer as being most black were the red samples. The grand mean rankings demonstrate that greenish to bluish blacks are perceived by the observers as “blacker” than yellowish and reddish blacks. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

In a previous work, the authors reported on the results of a color naming experiment performed on native Italian speakers regarding the location of focal colors and centroids in the Uniform Color Scales of the Optical Society of America color system. That work was aiming at comparing such data with those previously obtained by Boynton and Olson (B&O) accounting for the differences in the paradigm and the language. The number of consistency and consensus colors in the different lightness plans was also reported but no information was provided on their placement. Though, such information is very important for any subsequent modeling stage. The objective of this article is to fill such a gap and share such data with the scientific community to provide a reference database for future investigation. Three different datasets were considered: the extended OSA (E-OSA), the reduced OSA (R-OSA), and the B&O's (B&O) sets of reference colors. Results show a good overlap among the locations of the consensus colors in the {L, j, g} color model between B&O and the subset of E-OSA colors overlapping with the B&O 424 colors (R-OSA), as well as a strong agreement on consistency. Furthermore, a close proximity among the centroids of homologue regions for the majority of the classes was found. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

In digital image capture, the camera signals produced by the D65 illuminant, once translated into tristimulus values of the CIE 1931 standard colorimetric observer (assuming the Maxwell-Ives-Luther criterion is satisfied), are considered good to produce accurate color rendering. An image obtained under any illuminant other than D65 does not appear realistic and the tristimulus values of the camera must be transformed into the corresponding ones produced by the D65 illuminant. This transformation must satisfy color constancy. In this work, the transformation is obtained by a color-vision model based on the Optical Society of America-Uniform Color Scales system [Color Res Appl 2005; 30: 31–41] and is represented by a matrix dependent on the adaptation illuminant. This matrix is obtained by minimizing the distance between the pairs of the uniform scale chromatic responses related to the tristimulus values of the 99 different color samples of the SG Gretag-Macbeth ColorChecker measured under a pair of different illuminants, one of which is the D65. Then any picture captured under a given light source can be translated into the picture of the same scene under the D65 illuminant. Metameric reason allows only approximate solutions. The transformations from Daylight and Planckian illuminants to the D65 illuminant have a very regular dependence on the color temperature, that appears to be the typical parameter for the color conversion. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

Visually assessed appearance is undoubtedly of great importance to the selection of fruit by the consumer at the point of sale while the food supply chain also heavily relies on colour assessment methodologies for the determination of product quality. The use of printed colour charts to assess the ripening stages of fruits (i.e., banana ripeness charts) and/or vegetables is common in the fresh produce supply chain, even though they have limitations. However, the development of a more reliable and an objective instrumental method is necessary to describe fruit ripeness using set colour appearance parameters rather than subjective evaluations based on colour charts. In this article, we report a novel digital imaging methodology that could be used by the fresh produce industry to estimate the ripening stages of bananas more accurately. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

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, 2012

Liu et al. [Color Res Appl 1995;20:245–250] compared the CIELAB hue angles under CIE illuminants D65 and A for quantifying the color appearance changes for gem materials. They found that CIELAB hue angle for some gem materials under illuminant D65 was larger than under A, which is contrary to the perceived blue and purple appearances under daylight and incandescent light sources, respectively. They called this phenomenon as the abnormal hue angle change in the CIELAB space for the gem materials. In this article, we note the proper way to quantify the appearance changes is to use chromatic adaptation transforms (CATs), since we are only concerning the color change of the illumination. At the same time, it is found that the chromatic adaptations in the sharper sensor space and in the cone fundamental space provide different results, the ones related to the latter being in better agreement with current blue-to-purple color appearance change. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

In the early stage of a design process, it is important to create numerous and varied possible color plans for the target consumer group. These color plans help individual designers quickly find a few good color design schemes and give the design team ideas for brainstorming. The color plan of a product consists of the color combinations of its components and decorative patterns, which strongly influence the feelings of customers and thus their desire to purchase. However, very few studies have discussed these issues. In this study, a consultation and simulation system for product color planning that helps designers obtain the optimal color planning for components and decorative patterns of a product is proposed. This system includes two parts: one uses the interactive genetic algorithm to establish a creative evolutionary system that can interact with a designer to explore novel design schemes; the other extends the boundary extract algorithm to establish a color simulation system that can apply colors to the areas of product components and decorative patterns for color simulation. Finally, a case study of color planning for a motorcycle model is used to verify the feasibility of the proposed system. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

A visual test was conducted to find color ranges in which a replacement stone is aesthetically compatible. This study describes a color calibrated image chain processing, from acquisition to display, that was used to simulate stone replacements on a realistic image of monument. Then, a visual test protocol was designed to locate color thresholds that separate a perceptible from an imperceptible replaced stone. A case study has been performed on the Aigues-Mortes medieval city walls (South of France): Fifteen naive observers rated 2160 proposals of simulated stone replacements. The observer's answers (acceptance or rejection) were used to compute color thresholds along three colorimetric axes in a physiological and device-independent color space (LMS). The results show that color thresholds are not centered on the mean color of the monument. Furthermore, lighter colors are not accepted, though these appear in the original wall. These color thresholds constitute a set of quantitative criteria for aesthetically compatible stones. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

According to the color yarns in the fabric, the fabrics can be divided into three categories: solid color fabrics, single-system-mélange color fabrics, and double-system-mélange color fabrics. The density of solid fabrics can be inspected with gray-projection method or Fourier analysis method. But the methods cannot be applied to yarn-dyed fabrics directly. A method for detecting the density of single-system-mélange color fabrics will be discussed in this article. By analyzing the pattern and color characters of single-system-mélange color fabrics, fuzzy C-means algorithm is proposed to classify the colors in the fabric image based on CIELAB color space first. With the color segmentation results, the fabric can be divided into different blocks. The yarns can be located in different blocks with different average gray-levels, and then the number of yarns can be counted in each block. The linear density of threads can be obtained by counting the yarns in a unit length finally. The experiment proved that the algorithm proposed in this study can inspect the density of single-system-mélange color fabric successfully. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

The purpose of this study is to analyze the color differences in the four fashion collections from New York, London, Milan, and Paris while focusing on 2010 Fall and Winter women's ready-to-wear collections. The colors of the fashion collections were collected from American Vogue's website www.style.com and analyzed by using the ISCC –NBS color system which is made up of 10 basic hues of pink, red, orange, brown, yellow, olive, yellow green, green, blue, and purple, and three neutral categories of white, gray, and black. In addition to these 13 categories, yellowish pink, gold, and silver categories were classified. For analysis, one-way ANOVA, the Scheffe test and the t-test were adopted. The result of analysis showed that there was a statistical difference in purple compared with the other colors examined. The London collection showed the highest ratio of use in purple, whereas the Milan collection contrarily showed the lowest ratio of use in purple. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

I report a curious double helix in psychophysical data. As recently reported, color complementarism structures at least 40 functional roles in vision including all Red-, Green-, Blue-peaked functions (e.g., color matching functions, Helmholtz–Kohlrausch effect, saturation discrimination, lightness discrimination, and wavelength discrimination). These can be modeled from the relative spectral power distribution (SPD) function of complementary colors (at requisite power ratios to neutralize complements). So, the SPDs three-dimensional (3D) structure is of interest. Extended to the hue cycle, the SPD is plotted in a rectilinear graph of wavelength versus wavelength with radiance vertical to the plane. In this rectilinear color mixture space, the white locus representing the illuminant chromaticity is not a single point (representing the junction of complementary pairs of wavelengths) but a sinusoidal curve whose 3D structure is a double helix, representing an SPD and its complementary SPD. The structure's purpose is possibly to store and access global complementary colors data across illuminants. © 2012 Wiley Periodicals, Inc.

Paper properties, including the chemical or optical characteristics influence the quality and colorimetric characteristics of final printed colors. In this study, the effect of gloss, texture, and whiteness of the paper on the printed colors were investigated. The study was applied on 10 coated papers with different texture, gloss or whiteness, and the same grammage using two inkjet printers. It was found that the reproducibility of the printer can be affected with the paper brand, and this effect is statistically dependent on the brand of printer. The kind of paper significantly influences the light fastness of the final printed colors, and this effect statistically depends on the printer. Although, the paper's properties such as gloss and whiteness affect the gamut volume, it is not totally possible to model this effect. The effect of paper on the colorimetric values of the final printed colors is statistically significant. However, the influence of the brand of printer on the color changes via the paper difference is not statistically provable. Edge frequency technique was introduced as an appropriate method for computing texture properties of papers. The texture difference computed by this method shows a suitable correlation with the color differences caused by changing the paper's texture; however, it depends on the printer's brand. Furthermore, there is a good correlation between the Edge frequency difference and the gamut volume variation for papers with different texture while the other parameters such as gloss and whiteness are the same. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

Red is traditionally connected with love and sex. However, the effect of red on human behavior still remains in question. Women with Internet personal ads registered on a web meeting site displayed photographs with their upper clothes colored in red, black, white, yellow, blue, and green. The dependent variable was the number of contacts received from men. It was found that women's ads with red received significantly more contacts. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

This article presents the research of relationship between the effect of retinal localized chromatic adaptation, the standard rendering methods, and perception of desaturated achromatic reproductions. Within the research, adaptations on three types of adaptation forms at times of 5, 10, and 15 min are performed. To define the impact of the effect, the samples for visual evaluation – the evaluation of the effect of retinal localized chromatic adaptation – are printed by using the gray balance phenomenon: with certain samples, the saturation of colors for which the adaptation is performed is made higher. The research results show the existence of correlation between the researched parameters and a need for further research and description of psychophysical effects in processes of graphic reproductions. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

Measurement uncertainties are propagated through the matrix calibration of a tristimulus colorimeter. It is shown that reference spectral uncertainties and the colorimeter signal uncertainties during calibration are simply scaled and combined in an applied measurement. Modeling shows that transforming x, y chromaticity and Y luminance can lead to lower chromaticity uncertainties than transforming X, Y, Z tristimulus signals themselves. Accuracy depends on the set of colours used for calibration, especially for measurements of displays. Uncertainties can be large and dominate errors due to accuracy of spectral matching to the CIE colour-matching functions. This is particularly true if commision international de L'Eclariage (CIE) Lab values are to be derived. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

This article deals with the possibilities that color affords architectural composition, the strategies facilitated through color as a vocabulary of expression. It primarily focuses on the rules of grammar and syntax of color, and to a lesser degree on the semantic meanings, as this would entail multiple interpretations by the observer. Following an analysis of architectural color classification systems suggested by other authors, we reason that there are three main groups of plastic strategies. These are not mutually exclusive, but rather, complementary to each other: (I) color can influence the perception of the visual properties of architectural shapes; (II) color can describe the building and (III) color can be arranged for its intrinsic value. Each of these strategies deals with a different level of knowledge of the building, which requires both subconscious and conscious mechanisms of identification by the observer. These are the color strategies used by architects to express a particular compositional purpose. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

Riemannian metric tensors of color difference formulas are derived from the line elements in a color space. The shortest curve between two points in a color space can be calculated from the metric tensors. This shortest curve is called a geodesic. In this article, the authors present computed geodesic curves and corresponding contours of the CIELAB (ΔE ), the CIELUV (ΔE ), the OSA-UCS (ΔE_E) and an infinitesimal approximation of the CIEDE2000 (ΔE₀₀) color difference metrics in the CIELAB color space. At a fixed value of lightness L*, geodesic curves originating from the achromatic point and their corresponding contours of the above four formulas in the CIELAB color space can be described as hue geodesics and chroma contours. The Munsell chromas and hue circles at the Munsell values 3, 5, and 7 are compared with computed hue geodesics and chroma contours of these formulas at three different fixed lightness values. It is found that the Munsell chromas and hue circles do not the match the computed hue geodesics and chroma contours of above mentioned formulas at different Munsell values. The results also show that the distribution of color stimuli predicted by the infinitesimal approximation of CIEDE2000 (ΔE₀₀) and the OSA-UCS (ΔE_E) in the CIELAB color space are in general not better than the conventional CIELAB (ΔE) and CIELUV (ΔE) formulas. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

Color technology needs specifications to which extent physical differences of stimuli correspond to differences in perception. Generalized linear models (GLMs) have proved successful to provide such specifications from choice-based experiments. However, the use of GLMs imposes practical restrictions on the experiment and stimulus parameters. We propose an alternative analytic approach based on machine learning and demonstrate its use in designing and analyzing choice-based experiments with multiple stimulus dimensions. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012;

Semantic-differential data of color emotions for color pairs were collected and examined with factor analysis (FA) and independent component analysis (ICA). The axial orientations of factors cannot be identified by FA, whereas they can be determined by ICA with the intrinsic statistical properties of data such as kurtosis. Three factors or components were extracted by FA and ICA. The factors extracted by FA with the varimax method were consistent with the primary factors: evaluation, activity, and potency. When ICA extracted components with positive kurtosis, the components did not match any of the primary factors. However, the independent components extracted by ICA for negative kurtosis were consistent with the primary factors, and similar to the factors obtained by FA. The results of ICA suggest that the evaluation, activity, and potency factors are independent dimensions in psychological space of color emotions for color pairs. The distributions of the factor scores in FA and the scores of the independent components obtained by ICA for negative kurtosis were not Gaussian, but they had negative kurtosis. These support the use ofICA instead of FA. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012

People get cataract in their eyes when they age. The color perceived by the senile cataract eyes desaturates because of the environment light that scatters in the eyes by the hazy crystalline lenses. We investigated the effect of the desaturation on brightness of objects in terms of the equivalent lightness L, which is composed of the achromatic lightness L and the chromatic lightness L. If the color desaturates, L becomes smaller and consequently L becomes smaller in the cataract eyes. L with and without cataract experiencing goggles at room illuminances to cover mesopic to photopic level was measured. Red, yellow, green, and blue patches of size 2° × 2° arc of the visual angle were investigated with the direct heterochromatic brightness matching between the color patches and a gray scale. Both L took about the same value. L with goggles was then transferred to the final L where the matching gray scale was observed without goggles to express the equivalent lightness of cataract eyes by the gray scale perceived by normal eyes. L with goggles was lower than L without goggles by about 10 L* units in all the four colors. This reduction was almost equal to the reduction of L* by the reduced transmittance of the goggles showing that there was no effect of color desaturation. The color appearance in the color patches was measured by the elementary color naming method, and the results clearly showed the color desaturation with goggles implying decrease of L. We concluded that the scattered environment light compensated the decrease of L to keep the brightness of stimuli unchanged. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011;

Our technique first creates abstract colour schemes by applying those rules to specific features of the interface or web page; the user then holistically modifies the scheme's overall colour cast, overall saturation, and light–dark distribution, producing colourings that are both harmonious and usable. We demonstrate experimentally that the software is relatively simple to use and produces colourings that are well-received by humans.

In an earlier article, the criteria for a colour harmony tool for computer interfaces and websites were described and used in the design of the Colour Harmoniser, our software implementation of a system that is based on classical rules of colour harmony, adapted and extended to suit graphical user interfaces.

In this article, we describe two sets of experiments that have demonstrated the usability and effectiveness of the Colour Harmoniser tool, compared with standard methods of colour selection. These experiments suggest that the tool functions somewhat more effectively than we originally anticipated, producing colour schemes that were rated more highly on several quality scales than those produced by random choice, by humans who self-classify as nonartists, and by humans who self-classify as artists. © 2011 Wiley Periodicals, Inc. Col Res Appl, 38, 218–228, 2013.