The aim of this study was to investigate the impact of signboard‐building color combinations on color harmony and legibility. Two hundred and three participants rated 54 signboard‐building color combinations against two scales of color harmony and legibility. In this article, the terms “brick,” “stone,” and “glass” refer to three types of building exteriors used in the experiment (ie, brick masonry, greystone, and curtain walls, respectively). Major findings are as follows: (a) there was a positive linear correlation between color harmony and legibility in all three types of building exteriors, (b) the type of building exterior affected the color harmony and legibility of signboard colors, (c) no hue‐related patterns were observed, (d) the effects of chroma differences on color harmony were weak and the effects of chroma differences on legibility were moderate, (e) the effects of lightness differences on color harmony and legibility were strong in brick, but the effects of lightness differences were weak in stone and glass, (f) white color combinations (ie, color pairs including white signboards) turned out to be the most harmonious and legible, and (g) color combinations of light signboards and dark buildings (negative polarity) were rated most harmonious and legible, with the exception of vivid red (positive polarity). The findings of this study provide insight into the characteristics of harmonious and legible colors in the context of signboard design.

There is abundant research indicating the existence of a stable mechanism of correspondence between semantic units and color. Researchers usually refer to it as synesthesia. This mechanism inspired the creation of a cross‐media mapping model (between semantics and color) to execute semantics‐color interaction and design, and a method to generate corresponding color combinations by semantic imagery. In this project, a semantics‐color mapping model was constructed based on user‐evaluated parameters of color relations and semantic dimensions. The model consists of six semantic dimensions corresponding to six multicolor relation scales. An attempt was also made to provide a synesthetic color combination corresponding to a user's semantic expectation. This method paved a path toward restoring semantics‐color synesthesia and generating color combinations by semantic control. The synesthetic mapping model will affect color perception and expression as well. The cross‐media mapping model can be applied not only in semantic‐driven color design but also in cross‐media interaction, cognitive and expressive aid, and other artistic fields.

Increased waste production is a by‐product of economic growth, and that is why countries worldwide are working on turning waste into useful resources and enhancing recycling effectiveness. Aside from using symbols and words for identifying which recycle bins for which types of recyclable materials, color is also a useful code and visual element in recycle bin design. This study conducted questionnaire survey (n = 418) among participants from Taiwan and from East Asia and the Pacific (EAP) to explore the current condition of resource recycling and determine the best color‐material pairings. This study's result suggests that the most frequently recycled material by participants from Taiwan and from EAP were paper and plastic. The study participants sorted and recycled materials as frequently as five to six days a week. From analyzing the pairings of four colors (red, green, blue, and yellow) with four recyclable materials (paper, glass, plastic, and metal), differences were found between participants from Taiwan and those from EAP. Because resource classification and color coding are different from country to country, this study found that color provides limited information of recycle bins.

This article proposed a novel approach to color measurement of a single yarn using hyperspectral imaging system (HIS). Due to the size of a single yarn, it is impossible for spectrophotometers to measure its color directly. The HIS can acquire the spectral reflectance of continuous bands within a region of interest on a yarn sample, which can achieve color measurement of a single yarn compared with traditional spectrophotometers. A single yarn is segmented from the background by a spectral matching method through adaptively setting threshold of Fréchet distance values. The spectral reflectance of single yarn is specified by a method that lightness of pixels used as weight. The experiment based on Pantone Cotton Chip Set shows that the interinstrument agreement between the HIS and a standard spectrophotometer Datacolor SF650 has a significant improvement after using the R‐Model, and the average percentage improvement of the color difference is up to 54.99%. The yarn segmentation comparative experimental results show that the proposed method to segment single yarn from background is better in retaining the edge information of the yarn than the modified K‐means clustering method, and the color of the yarn segmented by the proposed method is more similar to the actual color of single yarn.

In this article, we present an evaluation method for the skin color distribution in the face area. Unlike previous methods that extract a specific area, our method subdivides the entire face into small regions and analyzes detailed, per‐frame textures. Our evaluation method for skin color distribution is based on facial feature points and includes segmentation that takes into account the facial skeleton and muscle orientation. The use of facial feature points enables a comparison at relatively equal positions on the face without depending on the shape or size of the individual's face. Our evaluation method is versatile, and as an application, we clarified age‐specific features and seasonal variations of facial color distribution. As a result of applying this evaluation method to the facial images of women aged 20 to 78 years, we confirmed that the lightness of the face decreased as age increased. In particular, the decrease in lightness was remarkable in the region along the cheekbone, from the temple to the center of the cheek. Furthermore, we analyzed the seasonal changes of melanin distribution in the face area. This showed that the melanin index increased particularly in the cheekbone area in the summer when the influence of ultraviolet rays became large. Our novel methodology and the data presented in this article will be useful in various fields, such as dermatology, cosmetics, and computer vision.

It is common practice in statistics to test the equality of two population means using, for example, the Student's t test, in the univariate case, or the Hotelling's T2 Test in the multivariate case. However, tests on the equality of population means are not well developed for testing the difference between two populations of color measurements. Methods for analyzing populations of spectral reflectance and L*a*b* measurements have been described for applications such as analyzing inter‐instrument agreement and repeatability. Methods have also been proposed for the analysis of color differences, but there are little written about techniques for testing whether two samples have the same probability distribution. This article focuses on testing the difference between color measurement probability distributions based on color difference. In addition, a metric is proposed called the threshold for color difference discrimination (TCDD, in units of ΔE), the color difference at which two populations can be considered to have different population distributions. A lower TCDD means smaller color differences between two samples can be resolved. Two parametric tests based on Hotelling's T2 test and a nonparametric permutation test were used to determine the TCDD for populations of color measurements with different variances and sample sizes. The TCDD was found to be smaller by tests using the Hotelling's T2 statistic, compared with a permutation test performed directly on color difference. It was also found, as expected, that larger sample sizes led to smaller TCDDs, as did smaller population variances.

A precise and shared description of gemstones color could greatly help their classification and market evaluation, and the key to develop an efficient color evaluation system for gemstones is the creation of a common descriptive language and assessment method. Nowadays, there is a lack of standards for the determination of color of gemstones, and traditional color assessment is exclusively based on the direct visual observation in some cases with lenses and microscopes. The underlying problem is that light impinging gemstones, due to their physical characteristics, produce scattering and multiple reflecting phenomena. This puts the process of gemstone color assessment out of the scope of classic colorimetry. What needs to be assessed is the overall appearance of the gemstone and this explain why, so far, it is realized mainly by visual inspection. In this study, we investigate the relationship between the use of color measuring instruments and the visual inspection method for the determination of gems color appearance. We set up a perceptual experiment involving 21 participants to correlate the measured and the perceived colors of a set of gemological samples. Results report the correlations between instrumental measures and the visual assessment of gemstones color appearance and can be a potential base for a future standard method for gemstones color assessment.

Metamer mismatching occurs in both the human visual system and digital imaging systems. Increasing the number of sensors in digital imaging systems is an efficient method to reduce the degree of metamer mismatching. This study investigates the number of sensors that are needed for the digital imaging systems to have a similar ability to the human sensor system in distinguishing colors from the perspective of metamer mismatching. Optimal spectral reflectance was generated, and a dataset with more than 47 million previously collected practical spectral reflectance functions was used to derive the metameric color pairs. Different sets of Gaussian‐shaped functions were designed to model the spectral sensitivity functions of the digital imaging systems. Both the metamer mismatching volumes and color differences were used to characterize the degree of metamer mismatching for pairs of samples, which were metameric to the imaging systems but appeared different to the human sensor system. The results show that the practical metamer mismatching volumes are substantially smaller than the theoretical ones. The results also show that both the metamer mismatching volumes and color differences are significantly reduced by increasing the number of sensors from three to five for the digital imaging system but are only slightly reduced by further increasing the number of sensors from five to seven. This indicates that five sensors is an efficient and optimal solution for an imaging system with Gaussian‐shaped sensors to have a similar ability in distinguishing colors compared to the human sensor system.

Expanded gamut printing is an approach in color reproduction that expands the color gamut of conventional CMYK printing processes via the use of additional colorants, such as Orange, Green, and Violet inks. This study evaluates the ability of commercial color management software to create an accurate solution for an expanded gamut printing system. In this study, two printing processes were used, an Epson SureColor P9000 inkjet printer/proofer and an HP Indigo 7900 digital production press, both with 7‐color expanded gamut ink sets. Software solutions from Alwan, CGS ORIS, ColorLogic, GMG Color, Heidelberg, and Kodak were evaluated. The systems were tested to see how well they could reproduce the colors in the entire PANTONE+ Solid Coated spot color library. It is shown that the solutions are able to reproduce 89% to 94% of the spot colors on the Epson P9000 inkjet printer and 77% to 87% of the library on the Indigo 7900, both to less than two CIEDE2000 (a typical tolerance in label and packaging work). The number of color patches in expanded gamut characterization test charts was noted, as this is still an area of proprietary, nonstandardized working practice. There are many different colorant combinations that can make the same color in expanded gamut printing. The ink build created by the different software solutions was studied, as it relates to press stability through appropriate choice of colorants. Pantone and Adobe provide everyday commercial tools for expanded color workflows. The study identified some issues with products from these companies that could confuse a less‐skilled user in a busy production environment. The conclusion of the study is that expanded gamut solutions for spot color printing produce totally acceptable results for digital printing processes; expanded gamut printing is ready, here and now. The findings show that expanded gamut printing can replace cumbersome conventional spot color workflows creating considerable savings and advantages, especially for label and packaging printers.

Blue colors were sparsely used in the first colored Japanese ukiyo‐e prints but became predominant during the 19th century, mainly due to the integration of the synthetic Prussian blue in the palette of the printers around 1830. For a long time, researchers have assumed that the traditional Japanese organic blue colorants such as indigo were substituted by cheaper Prussian blue. Some analytical studies conducted on such artworks showed evidence of the common use of indigo and Prussian blue in Japanese paintings, alone or mixed together. Recent measurements carried out on bluish areas of an ukiyo‐e designed by Utamaro showed the simultaneous use of the two pigments. However, if visible reflectance spectroscopy suggested the single use of Indigo, Fourier transform infrared spectroscopy (FTIR) also indicated the presence of Prussian blue. These results question about the possible identification of all the pigments of a colored mixture by using a single analytical technique. Without using FTIR spectroscopy, the Prussian blue would not have been detected, whereas on infrared spectra the expected specific bands ascribed to indigo are not identified. The objective of this work is to investigate mixtures of pigments, using noninvasive spectroscopic techniques in order to assess their limits of detection. Fluorimetry, hyperspectral imaging, and infrared spectroscopies have been performed on three color charts made of indigo, Prussian blue, and mixtures of them at different proportions of matter. The results emphasize the systematic identification of Prussian blue thanks to infrared spectroscopy, whereas the identification of indigo, mixed with Prussian blue, appears to be more challenging.

Psychophysical experiments of colour appearance, in terms of lightness, colourfulness, and hue, were conducted outdoors and indoors to investigate whether there was any difference in colour appearance between outdoor and indoor environments. A panel of 10 observers participated in the outdoor experiment, while 13 observers took part in the indoor experiment. The reference white had an average luminance of 12784 cd/m2 in the outdoor experiment and 129 cd/m2 in the indoor experiment. Test colours included 42 colour patches selected from the Practical Coordinate Color System to achieve a reasonable uniform distribution of samples in CIECAM02. Experimental results show that for both outdoor and indoor environments, there was good agreement between visual data and predicted values by CIECAM02 for the three colour appearance scales, with the coefficient of variation values all lower than 25 and the R2 values all higher than 0.73, indicating little difference in the three dimensions of colour appearance between indoor and outdoor viewing conditions. Experimental data also suggest that the observers were more sensitive to variation in lightness for grayish colours than for highly saturated colours, a phenomenon that seems to relate with the Helmholtz‐Kohlrausch effect. This phenomenon was modeled for predicting perceived lightness (J′) using the present experimental data. The new J′ model was tested using three extra sets of visual data obtained both outdoors and indoors, showing good predictive performance of the new model, with an average coefficient of variation of 14, an average R2 of 0.88, and an average STRESS index of 14.18.

The overall objective of this study is to confirm the method of determining the accuracy of Kubelka‐Munk reflectance theory (KMRT) for composite materials after undergoing aging unrelated to surface exposure. The specific aims of this study include comparisons of optical characterizations for two dental resin composite materials before and after aging in darkness. Aging of five shades of two nanohybrid dental resin composite materials was accomplished under relatively normal room conditions in a dark enclosure for over 3 years. The accuracy of KMRT was assessed and optical absorption and scattering and color and translucency characterizations were performed. The magnitudes of the error of nonlinear regression of reflectance after aging to KMRT are well within the limits of expected measurement error as applied to regression analysis. The characterizations of inherent optical scattering, inherent color, and translucency indicate that aging in darkness will have some effect for at least some shades of the materials studied. KMRT is a reliable method to predict the reflectance of dental resin aged in darkness and permits subsequent clinically relevant optical characterizations of materials aged in this manner. Although changes in optical scattering were detected due to this aging, such changes appear to have a negligible clinical effect on color and translucency.

This study investigated the effect of contrast in neutral‐, warm‐, and cool‐colored spaces on spatial memory. Spatial memory was measured in terms of architectural scale and recollection of architectural elements and furniture. Participants (N = 114) viewed a short virtual simulation video of a residential studio and were asked to sketch a map of the architectural elements on distributed grid paper. Spatial memory was measured in terms of scale, and item recall rate. Contrast and hue had no significant effect on the memorization of proportional scale. However, high‐contrast schemes allowed for a significantly higher recollection of architectural elements than low‐contrast schemes. In comparing the effect of hues, a significant difference was seen in recalling detailed furniture and lighting items. Participants reported significantly better spatial memory of neutral and warm color schemes than of cool color schemes. There was no interaction effect between contrast and hue in the color combinations. These results can be applied in the design of color schemes for architectural spaces requiring enhanced spatial cognition and memory.

The color of mineral pigments changes obviously with their particle size. However, how the particle size of these mineral pigments affects the color of the mineral pigment color block remains unclear. Based on optical principles and the physical properties of mineral pigment particles, our analysis found that changes in the particle size not only nonlinearly affect the behavior of light at the first surface of the mineral pigment color block, but also affect the interaction of light with the particles within the body of the mineral pigment color block, ultimately changing the spectral reflectance and color of the mineral pigment color block. Finally, we derived a nonlinear monotonically decreasing relationship between the particle size and the spectral reflectance. The experiment conducted in this article selected six kinds of mineral pigments as color block samples and observed the changes in the spectral reflectance and color value with the particle size. These studies are beneficial for color researchers conducting scientific research related to mineral pigments.

The objective of this study is to determine if men would follow the “red effect” when choosing colors for women to wear on a date, and also to determine if the colors that men would wear when going on a date would be the same as the colors that females (their date) would wish them to wear. A set of psychophysical data was generated from this experiment, where participants were asked to rank a set of 10 colored samples based on preference for each question asked. There were three different sets of colored samples. The set of colored samples given to the participant depended on the question. A total of five questions were asked. Scaling analysis was done on the data to organize a set of items according to preferences providing values, an interval scale (Z values), that correspond to the relative perceptual differences among the stimuli. The Z values were graphed to show the general preference of colors for women to wear, and the preference of colors for men to wear. A Spearman's rank‐order correlation coefficient (SRCC) was calculated comparing each individual's rank order with the mean rank order for that specific question. An average Spearman's rank order was calculated for each question and each gender in order to determine the variability in answers. Scaling results indicate that men follow the “red effect,” but women preferred to wear other colors such as turquoise, blue, or yellow depending on the outfit. Males and females agreed that no matter the colored bottoms (denim or black), blue was the preferred color top for men to wear. SRCC results showed a lot of variability between individual answers and the mean answer indicating that participants' rankings did not necessarily agree with general color preferences presented in the scaling analysis. While scaling analysis might suggest certain color preferences such as men following the “red effect” and women preferring to wear blue, the poor correlation found using SRCC between the individual answers and the mean rank orders suggests that color preferences for each individual are inherently unique.

Small, supra‐threshold color differences are typically described with Euclidean distance metrics, or dimension‐weighted Euclidean metrics, in color appearance spaces such as CIELAB. This research examines the perception and modeling of very large color differences in the order of 10 CIELAB units or larger, with an aim of describing the salience of color differences between distinct objects in real‐world scenes and images. A psychophysical experiment was completed to compare directly large color‐difference pairs designed to probe various Euclidean and non‐Euclidean distance metrics. The results indicate that very large color differences are best described by HyAB, a combination of a Euclidean metric in hue and chroma with a city‐block metric to incorporate lightness differences.

The outcome of a print in production run plays a crucial role in commercial and packaging printing. In the growing packaging industry, colorfulness and saturated prints with high chroma attract the eye of the consumer. The design and layout of a packaging carton comprise of images that consist of halftones in the print process, which demand attractiveness and visibility using bright colors. In this research, an effort has been made to identify and analyze various parameters involved in offset lithography affecting color attributes of prints. This study also focused on the investigation of the best process conditions that would yield optimum color values through multiresponse factors such as chroma and lightness. A general full‐factorial Design of Experiments (DOE) approach was used to evaluate the effect of prepress parameters such as screen ruling and dot shape and press parameters such ink viscosity and paper smoothness. These parameters were then optimized using a customized response surface design. From the experiment, it was observed that viscosity of the ink was a significant factor that majorly controls the color attributes. The surface smoothness of the paperboard was one of the factors influencing the improvement of color reproduction. A smoother surface makes even contact during ink transfer in the offset printing machine and hence reflects color with a higher chroma. The optimum parameters were as follows: 15 Pa s ink viscosity, 0.77 μm paper smoothness, and 200 lines per inch (lpi) screen ruling that resulted in increasing chroma (C*) in the middle and shadow tones in the halftones.

Generating high‐quality sequential color schemes for maps is challenging for most mapmakers. This article presents a harmony‐based approach for automatically generating sequential color schemes for maps. The proposed approach consists of two steps: (a) color harmony quantification for sequential color schemes on maps and (b) color scheme generation using quantified color harmony factors. The approach was tested using three experimental maps, including the Chinese water body density index map, Chinese vegetation cover index map, and Chinese population density map. Effectiveness was evaluated by comparing color schemes generated by the proposed approach with those created by the probability‐based method and ColorBrewer. Twenty‐six participants were invited to rate each map color scheme using a 5‐point scale. A t test was also used to examine the significance of the difference. The results show that the mean points of color schemes using the proposed approach are higher than those using the probability‐based method, and the corresponding P‐values are far lower than .05, which suggests that the proposed approach is better than the probability‐based method and can improve the sequential color scheme quality in automatic ways. The mean points of color schemes created using the proposed approach are also slightly higher than or similar to those of ColorBrewer, which are well‐known map color schemes manually designed by an experienced cartographer. This result further suggests that the proposed approach can meet the requirement of automatic generation for high‐quality sequential color schemes on maps.

This study describes the lightfastness properties of printed foil samples due to long‐time exposure. Lightfastness is an important property for any kind of print products to assess their print stability. The fastness properties of prints can be described in terms of print durability and image stability. It may also be used for verification of printed expiry date and authenticity or validity of the product. Moreover, any kind of deterioration in package print quality will affect the product's sale adversely. Little work has been conducted to study the fastness properties of printed films and foils. In this work, blister foils printed in the gravure printing process have been taken as the sample as they have extensive usage in food and medicine packaging. An artificial lightfastness tester BGD 865/A Bench Xenon Test Chamber (B‐SUN) is used to study the light fastness of Cyan, Magenta, Yellow, and Black inks on the foil. The spectral curves and colorimetric values are measured using an Ocean Optics Spectroradiometer (DH2000BAL) before and after exposure. A kinetic model is proposed to predict the fading rate of the printed foil. The optimal model has given excellent prediction with a correlation coefficient of 0.90 to 0.93 for Cyan, Magenta, Yellow, and Black prints, respectively. The largest color difference ΔE00 is achieved for Yellow print followed by Magenta. Cyan and Black prints have shown small changes with time when the gravure prints are exposed to the artificial aging chamber.

Three numerical methods are presented for finding the smoothest reflectance curve associated with a given triplet of tristimulus values. The methods differ in how “smooth” is defined, and also differ in the domain of colors over which they are applicable. The first method is very quick and applies to any tristimulus values, but sometimes can yield reflectance curves with portions that fall outside the range 0 to 1. The second method applies to colors within the spectral locus (real colors) and guarantees that the reflectances produced are positive. The third method applies to colors within the object color solid (object colors) and guarantees that the reflectances fall within the range 0 to 1. The methods are shown to create reflectances that closely resemble those of real colors (natural and synthetic). Focus is given to implementing the numerical methods in very short MATLAB/Octave functions and to understanding the numerical behavior of the methods near the limits of their respective domains of applicability in terms of matrix conditioning and discretization artifacts.

The proper dispersion and stabilization of titanium dioxide/extender in a coating is critical for color development. Color development is much more challenging when it comes to point of sale tinting. This color needs to be reproducible and accurate after machine tinting. What decides the color development in a zero rutile base containing extenders? This article studies the raw material interactions and its effect on color development.

This research was conducted to evaluate the effects of cold atmospheric plasma treatment on the color of Hyssop (Hyssopus officinalis L.) and also to compare the usage of the spectrophotometer vs the color imaging instrumentation for the evaluation of the treatment on the color parameters. The experiments were investigated at different treatment times of 1, 5, and 10 minutes and the voltage values of 17, 20, and 23 kV. Possible changes of color were evaluated by using CIE L*a*b* values obtained with HunterLab colorimeter and CIE L*a*b* values obtained with a digital still camera (DSC) using digital image processing (MATLAB software). The values of L*, a*, and b* of the samples were obtained using both the methods. The results revealed that the L*, a*, and b* values of the treated Hyssop samples changed with increasing the treatment time and the voltage applied. Evaluating the interaction effects revealed that there was a significant difference in the (−a*/b*) ratio. In addition, the results showed that the effects of all variables on the color parameters were significantly different in the case of the DSC using digital image processing. However, these effects were not significantly different using HunterLab colorimeter except for time variable and interaction effects of a* and (−a*/b*) ratio. The lightest green color and the maximum chlorophyll content loss were observed for 23 kV applied over 10 minutes. Based on the results, the digital image processing can be used as a practical tool to study the variations at the color of dried Hyssop leaves after cold plasma treatment.

We have developed a procedure to achieve a high accuracy of color capture for digital still cameras for cultural heritage digitization. The procedure uses a standard color target and additional spectral measurements directly on the artwork. A set of complementary colors is determined thanks to an initial analysis of the digital image and a comparison with the standard color target. The developed procedure results in a digital copy that better represents the colors of the original than using only standard color targets.

An optimization model for luminous efficacy of a spectrally tunable light‐emitting diode (LED) daylight simulator under constraint of metamerism index was developed. It was first reported that the optimal spectrally tunable LED daylight simulator of AA grade for D50, D55, D65, and D75 standard illuminants could consist of two quantum dot‐integrated LEDs (QDLEDs) with the ultraviolet chip and two other QDLEDs with the blue chip. The optimized spectral parameters of each QDLED, as well as photometric and colorimetric performances of D50, D55, D65, and D75 daylight simulators, were obtained by maximizing luminous efficacy under the metamerism index for both a visible and ultraviolet range less than 0.25. The limit luminous efficacies of four daylight simulators using four QDLEDs under the ideal case will reach 181 lm/W to 205 lm/luminous efficacies with a radiant efficiency of both the ultraviolet and blue chips of 60%, as well as a quantum efficiency of a quantum dots layer of 90%, will reach 100 lm/W to 112 lm/W.

Near‐ and short‐wave IR emission spectra of printed cotton/nylon blend fabrics coated with inorganic compounds in order to tune their diffuse reflectance behavior to the ones with woodland and desert backgrounds are investigated. In this regard, cotton/nylon blend fabrics printed with a four‐color digital pattern were used as the substrate, and different concentrations of zirconium and cerium dioxide (ZrO2 and CeO2) with and without citric acid as a cross‐linker were loaded on these fabrics using the pad‐dry‐cure method. The diffuse reflectance of the coated fabrics with various concentrations of nanoparticles and a cross‐linker was first measured by near‐infrared (NIR) diffuse reflectance spectroscopy (DRS). Then, fabrics with an optimum concentration of nanoparticles and appropriate reflectivity profiles similar to woodland and desert were investigated by field emission scanning electron microscopy (FE‐SEM), energy‐dispersive spectroscopy (EDS), washing, and rubbing fastness properties. In general, NIR and short‐wave infrared (SWIR) reflectance of fabrics coated with ZrO2 and CeO2 nanoparticles in range of 1% to 1.5% (w/v [%]) was suitable for matching with different environments. According to the findings obtained from the durability test, it was concluded that the washing fastness of the treated fabrics with CeO2 nanoparticles was excellent in both environments. FE‐SEM images of the treated fabrics containing ZrO2 and CeO2 indicated that the presence of nanoparticles on the surface of fabrics in woodland patterns was greater than the desert ones. However, the coated fabrics with CeO2 and citric acid in the woodland pattern have shown better dispersion with a mean particle size of 30 to 60 nm.

In this study, our aim is to clarify the color combination rules of the human‐preferred Papilionidae butterflies as aesthetic objects. A set of 118 butterfly images, including color polyphenism from the 47 Papilionidae species that are generally preferred by humans, was selected. These images were classified using hierarchical cluster analysis based on similarities of lightness, chroma, and hue attributes in CIELAB space, determined using histogram intersection. Then, the color distributions and combinations in each cluster were analyzed using a Gaussian mixture model and the color combination types defined in the present study. Accordingly, we obtained the following main color combination rules of human‐preferred Papilionidae: (a) dominant low lightness and contrasting lightness components, (b) dominant low chroma and similar chroma components, and (c) dominant orange to yellow‐green hue and similar hue components. These rules partly agree with the robust harmony principles found in previous research. We infer that the cognitive effects concerning the processing fluency through these color combination rules influence human aesthetic responses.

Strong associations exist between colours and concepts or words. Understanding these associations, sometimes referred to as colour emotions, is important for effective use of colour in art and design. Traditionally the relationships have been systematically explored in experiments where participants scale colours according to bipolar adjectives such as warm‐cool. In this article, a method for exploring the relationships between words and colours is suggested and is demonstrated. A psychophysical experiment is described where participants select colours based on words. The data are used to show that many similarities between the word‐colour relationships for UK and Chinese participants although some interesting differences are also revealed. The method makes explicit the observation that there is not a one‐to‐one relationship between words and colours. The method could be used to explore word‐colour relationship for specific words and participant groups or could be used to generate ground‐truth data for testing methods for automatically generating the word‐colour relationships.

The local environment defines the traditional designs and color of buildings in remote wilderness areas. Color, an integral element of the traditional architecture, is related to the culture, experience, perception, and beliefs, which forms a part of the traditional knowledge of the user. Some ethnic groups have been using some specific color patterns in their houses for generations, which have been carried forward in their traditions and customs. Recognizing this, a study to document the color preference and motivations for the preference of specific colors by an ethnic community residing in the interior valleys of western Himalaya was conducted. By group discussions, 13 indicators, which further merged into five motivation categories, were identified. Semistructured interviews (n = 159) were conducted to assess the perception of selected ethnic groups toward color preference. This study reveals that color preference in architecture is influenced by psychological and sociocultural reasons that vary with gender and age classes.

In this study, the 28 primary colors and 11 complementary colors suggested by Chang et al in their investigation on building colors in Wanhua District of Taipei City were taken as color samples. The two‐color combination mode was adopted to obtain 308 simulation photos, and two‐color harmony was discussed from the perspective of visual evaluation using psychophysical tests. This study explored building façade color harmony in the CIELAB color space, and the relationship between the color attributes (hue, lightness, and chroma) and the color harmony, and between the differences of the color attributes and color harmony. It found that a high lightness of a building's primary color is associated with a high level of building color harmony, while the color harmony is reduced when the color falls in the green or blue sector in the CIELAB color space; a greater lightness difference between building façade colors is associated with a higher level of building color harmony, while the colors are disharmonized when they tend to the blue sector in the CIELAB color space. The contribution of this study is to summarize the principles for the application of building color harmony in urban renewal, and proposed suggestions on building color harmony in the urban renewal process.

Nowadays, many factors are involved in lighting design to achieve targeted lighting in addition to meeting the user's requirements and security to avoid energy loss. As building indexation at night is one of the main reasons for building lighting, it is necessary to make a decision to reduce energy consumption and increase observer's attention. The present study investigated the relationship between the correlated color temperature of the background and building based on the amount of visual attention and the amount of visual desirability. In this article, using a factor analysis approach, a range that attracts visual attention and visual desirability at the same time was obtained, and it is called viewerphilic perspective. The results presented in the form of a diagram show a relationship between the variables that directly and indirectly influence the formation of a viewerphilic night perspective. The results showed that the elements with a high correlated color temperature in the background and a low correlated color temperature and neutral color were in the viewerphilic range, while the elements with a low color temperature and a background with a high color temperature was in the range of viewer phobic.

Emotional reactions to red, green, blue, and gray colors in a living room were investigated using a self‐report measure. Participants first watched a short video of a 3D model of a living room. Next, they were asked to match the living rooms with facial expressions of six basic emotions. The most stated emotions associated for the red room were disgust and happiness, while the least stated emotions were sadness, fear, anger, and surprise; for the green room, neutral and happiness were the most stated emotions, and anger, surprise, fear, and sadness were the least stated ones; for the blue room, neutral was the most stated emotion, while the least stated emotions were anger and surprise. Neutral, disgust, and sadness were the most stated emotions for the gray room. Gender differences were not found in human emotional reactions to living rooms with different wall colors.

When users select products, they consider the emotional experience resulting from the color of the product. However, the emotional demands of users for product color are multidimensional and diverse. It is very important yet difficult to accurately grasp multiemotional image requirements and effectively convert them into design elements. Therefore, multiemotional product color design (MEPCD) has become a very important and challenging research topic. In this article, a novel MEPCD system using gray theory (GT) and nondominated sorting genetic algorithm‐III (NSGA‐III) is proposed to effectively solve the MEPCD problem. First, the image perception spaces of users, which exist in different emotional dimensions, were collected using factor analysis and the semantic differential technique. Then, GT was used to establish a multidimensional emotional product color image evaluation model. Finally, NSGA‐III was used to optimize and design a multiemotional color scheme for a product. Furthermore, according to actual conditions, an MEPCD system was established based on the proposed method. The design case study shows that the method and design system proposed in this article have a certain range of applicability and can effectively improve the practicality of MEPCD.

There are few studies on the tricolor design optimization, and the influence of color‐area ratio on users' emotion has been ignored. This article aims to achieve multiobjective optimization of tricolor product color design. Two modes of color‐area ratio are put forward. Using the proposed method of generating tricolor schemes, 368 tricolor schemes of the representative baby carriage are designed. Through questionnaire survey, color images are screened, and combined with correlation analysis and factor analysis, five perceptual features of color design are determined as “Order,” “Excitement,” “Temperature,” “Color harmony,” and “Users' emotional preference.” From two perspectives of color information processing, radial basis function neural networks are used to construct two emotional evaluation models. By integrating the radial basis function neural networks and a genetic algorithm, this study achieves multiobjective optimization of tricolor product color design for two optimization objectives of color harmony and users' emotional preference. Verification results show that the optimization schemes are significantly better than other schemes. Due to similar product characteristics, children's electric car is utilized to verify the generalization capability of the optimization method proposed in this article. It has been demonstrated that the optimization schemes achieve higher scores than randomly selected color schemes and the actual subjective scores match with the predicted scores computed by the color optimization method.

In recent literature, a new chromatic adaptation transform, CAT16, has been published to improve upon the widely used CAT02 model. The CAT16 model is based on the form of the CAT02 transform adopted in CIECAM02, but uses a slightly different sensor space to fix some gamut problems plaguing CIECAM02 and adopts a two‐step CAT to ensure symmetry and transitivity. CAT16 is included in CAM16 but is also being promoted as a stand‐alone CAT, one that can be used outside of the CAM16 model. However, the use of CAT16 as a stand‐alone model can cause inconsistencies in the calculated corresponding colors due to the presence of the relative luminance of the adapting white (Yw) in the von Kries‐Ives gain control factors. Such inconsistencies are not present for the stand‐alone version of the CAT02 model, which, unlike the version adopted in CIECAM02, does not include the Yw factors. CAT16 should therefore be modified by omitting the Yw factors. In this article, we will briefly discuss these issues in more detail and provide a consistent two‐step CAT adopting the CAT16 sensor space.

Women might experience modulation in their perception and cognition of colours and odours during the menstrual cycle, but how women's impressions of and correspondence between colours and odours differ according to the cycle changes remains unknown. Here, we experimentally examined women's performance of several tasks, including evaluation of impressions of colours and odours, matching/nonmatching of colours with odours, and identification of odours, comparing two phases: the beginning of menstruation and ovulation. The results showed that participants had similar impressions of colours and odours and made similar colour choices for odours in both the menstrual and ovulation phases, while “pleasant‐unpleasant” impressions of colour and odour might vary according to the menstrual cycle. We found no significant differences in odour identification between the phases. The findings imply that hormonal changes during the menstrual cycle might affect “pleasant‐unpleasant” impressions of colour and odour but not other features regarding impressions or crossmodal correspondence. In future studies, examination with a large number of participants is necessary.

Threshold vs. intensity (tvi) functions were measured under conditions in which the slope of the rising branch approximated the deVries-Rose law in order to evaluate the contribution of intrinsic visual noise (dark light, Eigengrau) to age-related elevations in threshold under photopic conditions. Data were obtained from 48 observers (20-88 years) using a temporal 2AFC procedure. The stimulus was centered at 8° nasal retinal eccentricity and consisted of a 560 nm, 14.4' test flash (10 ms) concentric with a steady 500 nm (12.9°) adapting field (13 intensity levels ranging from 0-9 log quanta · sec(-1) · deg(-2)), which resulted in clear scotopic and photopic branches. Photopic thresholds increased linearly with age at a rate of 0.08 log unit per decade at the cornea. The mean slope of the rising portion of the tvi functions (in log-log coordinates) was 0.62, and not correlated with age. Dark light values increased with age, but not significantly. Dark light was a statistically significant predictor of individual differences in absolute photopic threshold, but it is not responsible for age-related increases in threshold under photopic conditions.

The purposes of this study were to measure areas of complete spatial summation (i.e., Ricco's area) for S- and L-cone mechanisms and to evaluate whether the sizes of Ricco's area could be explained in terms of either the densities of photoreceptors or ganglion cells. Increment thresholds were measured at the fovea and at 1.5°, 4°, 8°, and 20° in the superior retina using a temporal two-alternative forced-choice procedure. Test stimuli ranging from -0.36 to 4.61 log area (min(2)) were presented on concentric 12.3° adapting and auxiliary fields, which isolated either an S- or L-cone mechanism on the plateau of the respective threshold vs. intensity function. The data indicate that from 0-20° retinal eccentricity, the size of Ricco's area is larger for the S-cone mechanism than the L-cone mechanism, increases monotonically for the L-cone mechanism, and, for both cone mechanisms, increases between 8-20° retinal eccentricity. This latter finding suggests that ganglion cell density rather than cone density defines the size of Ricco's area in the parafoveal and peripheral retina.

Colour constancy assessed by asymmetric simultaneous colour matching usually reveals limited levels of performance in the unadapted eye. Yet observers can readily discriminate illuminant changes on a scene from changes in the spectral reflectances of the surfaces making up the scene. This ability is probably based on judgements of relational colour constancy, in turn based on the physical stability of spatial ratios of cone excitations under illuminant changes. Evidence is presented suggesting that the ability to detect violations in relational colour constancy depends on temporal transient cues. Because colour constancy and relational colour constancy are closely connected, it should be possible to improve estimates of colour constancy by introducing similar transient cues into the matching task. To test this hypothesis, an experiment was performed in which observers made surface-colour matches between patterns presented in the same position in an alternating sequence with period 2 s or, as a control, presented simultaneously, side-by-side. The degree of constancy was significantly higher for sequential presentation, reaching 87% for matches averaged over 20 observers. Temporal cues may offer a useful source of information for making colour-constancy judgements.

The goal of our study was to evaluate colour vision during high-altitude mountain climbing without supplemental oxygen. Two Himalayan expeditions were invited to test their colour perception at both the highest possible altitude and on the largest possible number of subjects. The panel desaturated D15 was used, because only a simple test could be transported to those altitudes. There were 2 evaluations (i.e., 4 eyes) at 7,000 m during the first expedition in 1997, and 3 evaluations (i.e., 6 eyes) at 6,500 m during the second expedition in 1998. The results were in perfect agreement and can be considered practically normal for all 5 mountain climbers.

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 6 subjects (2 in Experiment 1, 3 in Experiment 2, and 4 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.