Some modifications to Hering's opponent‐colors theory

Some modifications are made to the achromatic color perceptions in Hering's opponent‐colors theory. They are the introduction of the reference color Gray and the use of the orthogonal coordinate system. The modified opponent‐colors theory has a symmetrical structure for the three opponent‐colors axes, whiteness‐grayness‐blackness, redness‐grayness‐greenness, and yellowness‐grayness‐blueness, and it unifies the Hunt and the Stevens and Jameson–Hurvich effects. It is also noted that two kinds of color‐appearance spaces exist. One is the color‐appearance space derived from color perceptions of object colors (called the CPS color‐appearance space). The other is that modeled from their colorimetric values for predicting color perceptions (called the UCS color‐appearance space). The CPS color‐appearance space is mainly described in this article. Scaling of the CPS color‐appearance space and the existence of the reference color perception Gray are discussed in detail. © 2001 John Wiley & Sons, Inc. Col Res Appl, 26, 290–304, 2001     

Color emotions for multi‐colored images

We investigate the emotional response to colors in ordinary multicolored images. In psychophysical experiments, using both category scaling and interval scaling, observers are asked to judge images using three emotion factors: activity, weight, and heat. The color emotion metric was originally developed for single colors, and later extended to include pairs of colors. The same metric was recently used in image retrieval. The results show that people in general perceive color emotions for multi‐colored images in similar ways, and that observer judgments correlate with the recently proposed method used in image retrieval. The intended usage is in retrieval systems publicly available on the Internet, where both the user and the viewing environment is unknown, which requires novel ways of conducting the psychophysical experiments. © 2010 Wiley Periodicals, Inc. Col Res Appl, 36, 210–221, 2011;     

A quantitative network model for color categorization

To clarify the higher‐order mechanism of human color perception, we measured the color appearances of 78 colored lights by an elemental color‐scaling method and by a categorical color naming method. The colors covered nearly the entire CIE 1931 xy‐chromaticity diagram with three different surrounds. The results showed that firm basic color zones derived by categorical color naming can be mapped with no overlap in an opponent‐color response space. We propose a network model with a threshold selector, maximum selectors, and multiplication units with gain factors to generate the categorical color responses quantitatively from the elemental color responses. The model can predict the categorical color naming results in different surround conditions with no change of parameters. This suggests that a nonlinear color vision mechanism for color categorization exists between the primary visual cortex (V1) and the inferior temporal cortex (IT) in the human brain. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 225–232, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10060     

Adequateness of a newly modified opponent‐colors theory

Two features of a newly modified opponent‐colors theory are examined for correctness: (1) The perceived chroma of pure color is different for different hues. This was confirmed by using Ikeda's UCS (Uniform Color Scales) formula and also by the maximum Munsell Chroma Values for different hues. (2) Chromatic colors with the same values of whiteness, blackness, grayness, and perceived chroma have the same perceived lightness and chromatic tone regardless of hue. This was confirmed by a theoretical analysis and observations of the color samples in the Practical Color Co‐ordinate System (PCCS) developed in Japan. Chromatic tone, a complex concept of object colors, is clarified. The structure of the newly modified theory and its corresponding color space were confirmed by observation of object colors. Furthermore, it was found effective for developing a color‐order system and its corresponding standard color charts to the modified theory. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 298–307, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10164     

Proposal of an opponent‐colors system based on color‐appearance and color‐vision studies

A new theoretical color order system is proposed on the basis of various studies on color appearance and color vision. It has three orthogonal opponent‐colors axes and an improved chromatic strength of each hue. The system has color attributes whiteness w, blackness bk, grayness gr, chroma C, and hue H. A method is given for determining Munsell notations of any colors on any equi‐hue planes in the system. A method is also given for determining grayness regions and grayness values on hue‐chroma planes in the system. It is concluded that colors with the same color attributes [w, gr, bk, C] but with different hues in the theoretical space have approximately the same perceived lightness, the same degree of vividness (“azayakasa” in Japanese), and also the same color tone. The tone concept, for example used in the Practical Color Coordinate System (PCCS), is clarified perceptually. The proposed system is a basic and latent color‐order system to PCCS. In addition, the concept of veiling grayness by a pure color with any hue is introduced. Further, relationships are clarified between generalized chroma c(gen) and grayness. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 135–150, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10234     

A hue rectangle and its color metrics in a modified opponent‐colors system

In the proposed modified opponent‐colors system, the hue regular rectangles show the chromatic coordinates of any chromatic colors better than hue circles. In the hue rectangles equihue and equichroma loci are shown together with equigrayness loci. In the color perception space of the modified opponent‐colors system, a city‐block metric must be used instead of a Euclidean one for distance. The reason for this is described in detail. The proposed color perception space constitutes a regular octahedron. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 171–179, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10046     

Comparing the visibility of low‐contrast color Landolt‐Cs: Effect of aging human lens

We measured response time, the number of nonresponses, response error, and subjective visibility evaluation for color Landolt‐Cs with a gray color background presented on a CRT display to young and old adults (mean ages: 22.3 and 65.9 years, respectively) and to the same young adults wearing glasses with filters simulating an aging human crystalline lens. Comparing the results of elderly and young subjects without the filter, the results of the elderly subjects showed a longer response time, higher nonresponse ratio, slower response speed, and lower visibility, particularly for gray and blue stimuli. Conversely, the results for the young subjects who were fitted with the filters showed tendencies similar to those of the elderly subjects. These results indicate that the yellowing of the human lens strongly influences the visibility of color targets in the elderly and that wearing the filters enables young adults to simulate the visibility of the elderly. It suggests that the simulated filter as well as the aging human lens modifies the effective luminance, effective luminance contrast, and color difference between the color target and the background on the retina. Moreover, the relationship between the subjective evaluation and the response speed changes remarkably with age, regardless of the filters, suggesting that not only the subjective evaluation but also the evaluation of the performance, such as response speed, is important in estimating visibility and controllability in the elderly. The filter used in the present study will be an effective tool for the young to evaluate the visibility of elderly adults in terms of both response speed and subjective evaluation of visibility. © 2004 Wiley Periodicals, Inc. Col Res Appl, 30, 5–12, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20071     

Color vision assessment‐2: Color assessment outcomes using single and multi‐test protocols

The main purpose of this study was to produce reliable, color assessment outcomes to examine the extent to which single and multi‐test protocols in use meet current clinical and occupational needs. The latter include the detection of small changes in chromatic sensitivity as the earliest signs of retinal and/or systemic disease, and the need to assess the class of color vision in congenital deficiency and to quantify severity of loss. Color vision was assessed using Ishihara (IH), Farnsworth Munsell D‐15, City University (CU, 2nd ed.) and Holmes‐Wright type A (HW‐A) lantern tests. All subjects also carried out Colour Assessment and Diagnosis and Nagel anomaloscope tests. The sample included 350 normal trichromats, 1012 deutans and 465 protans (age 31.1 ± 12.4, range 10‐65 years). The results reveal the trade‐off between sensitivity and specificity, depending on the number of errors accepted as a pass on the IH test. The D‐15 and CU tests pass all normals and almost 50% of subjects with color vision deficiency. The HW‐A lantern passes all normals, 22% of deutans and 1% of protans. The multi‐test protocols designed to identify protans and to pass only subjects with mild color loss, pass over 50% of protans and deutans. Many of the subjects who fail exhibit less severe loss of color vision than others who pass. When high sensitivity for detection of congenital deficiency is achieved, single‐test protocols fail many normal trichromats. Multi‐test protocols produce large variability and fail to achieve desired aims.     

Color appearance of afterimages compared to the chromatic adaptation to illumination

The color appearance of negative afterimages was measured by the elementary color naming method, and the results were compared with those obtained by the two‐room technique. Twenty adapting stimuli were presented on a display sequentially. Subjects first assessed the color appearance of the stimuli. After looking at the adapting stimulus for 10 seconds, the subjects assessed color of the afterimage. Apparent hue of the afterimage was in general not opponent color to the adapting color. The relation between the adapting stimuli and the afterimages was analyzed by the angle difference Δθ, when apparent hues are expressed by the angles of the points on the polar diagram of the opponent color theory. The relation relationship of Δθ to the angle of the adapting color θ_ing was quite similar to the results obtained by the two‐room technique, implying that the chromatic adaptation shown by the afterimage also occurs in the brain rather than in the retina.     

Bubble breakup with permanent obstruction in an asymmetric microfluidic T‐junction

Bubble breakup with permanent obstruction in an asymmetric microfluidic T‐junction is investigated experimentally. The breakup process of bubbles can be divided into three stages: squeezing, transition, and pinch‐off stages. In the squeezing stage, the thinning of the bubble neck is mainly controlled by the velocity of the fluid flowing into the T‐junction, and the increase of the liquid viscosity can promote this process. In the transition stage, the minimum width of bubble neck decreases linearly with time. In the pinch‐off stage, the effect of the velocity of the fluid flowing into the T‐junction on the thinning of the bubble neck becomes weaker, and the increase of the liquid viscosity would delay this process. The evolution of the minimum width of the bubble neck with the remaining time before the breakup can be scaled by a power–law relationship. The bubble length has little influence on the whole breakup process of bubbles. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1081–1091, 2015     

Color and culture: Innovations and insights since Basic Color Terms—Their Universality and Evolution (1969)

Fifty years ago, in 1969, Berlin & Kay published Basic Color Terms—Their Universality and Evolution and set in‐motion a large‐scale systematic research program for studying color naming and categorization across first‐language speakers from different ethno‐linguistic societies. While it is difficult to gauge the impact a research program can make over 50‐years, many linguists, anthropologists, cognitive scientists, and perceptual psychologists consider the Berlin & Kay book as one of the top‐most influential works in cross‐cultural studies not only of color linguistics, but of cognition and language more generally. Today reverberations from the Berlin & Kay (1969) research program continue to resonate through recently available data sets that are being examined with new quantitative analysis methods and modeling approaches. Here we review the origins of the Basic Color Terms phenomenon, and note a few of the numerous directions from which on‐going related work continues to bring forth interesting results in the color categorization arena.     

Color characteristics of costumes for Korean folk festivals and color consciousness of Koreans

The purpose of this study was to identify the color characteristics of Korean culture, the color consciousness of Korean people based on their arche‐pattern sentiment, and to analyze the colors of the costumes of Korean folk festivals, which clearly suggest the archetype of Korean tradition. The range of this study is focused on Korea's important intangible cultural assets in which the colors used in folk festivals were fully expressed, and 20 folk games and plays were selected from among different festival events. Hundred and fifteen pictures from these 20 folk games/plays were used to extract the costume colors and conduct color analyses. Among 647 colors extracted in total, this article used 199 colors after excluding overlapping colors. The results show that Korean folk festivals have served as the medium of nondifferentiation that goes beyond the differentiated order of reality. Costumes for these Korean folk festivals, such as folk games and folk plays, have a sacred meaning as ritualistic robes. Five element colors in these costumes for the Korean folk festival are used as a means of circulatory thinking and as a symbol of Chaos—the very origin of undifferentiated thinking—beyond one's daily lives. It was found that these highly chromatic five element colors have always been used, wherever this undifferentiated thinking was strongly expressed. Delivering visually strong impacts, these five element colors symbolize the concept of the Arche‐pattern theory, being related to infinite freedom without any restrictions. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010     

Large‐field color matching functions

Color‐matching functions (CMFs) were derived with the Maxwell method for 10 subjects using two field conditions: (1) horizontally bisected circular 10° and (2) vertically bisected rectangular 102° (wide) × 50° (high). The primary set was composed of 453–533–601 nm components with a mean full‐width at half maximum of 18.3 nm; the reference field was illuminated with daylight fluorescent lamplight. Field size had a significant effect on the shape of the resulting CMFs. Under the large‐field conditions subjects were less sensitive to shorter wavelengths as characterized with the b? function and had higher sensitivities to the longer wavelengths as characterized with the r? function. © 2005 Wiley Periodicals, Inc. Col Res Appl, 31, 18–29, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20170     

Practical color barrier‐free illumination for deuteranopia using LEDs

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

Optimization of LED‐based light blendings for object presentation

This study looks at the perceived quality of light‐emitting diode (LED)‐based lighting of various colors. The objective was to find out whether LEDs could provide better (i.e., more relevant and acceptable) lighting than that which is obtained with standard halogen or fluorescent sources. The perception of objects was assessed under different lighting schemes. Subjects were invited to add red, cyan and/or amber to white LED‐based light to match the halogen and fluorescence rendering on specific targets: a color chart and a painting. They were also asked to rate the difference between the two, and to express their preference. The results obtained for the perception of LED‐based lighting were quite positive. Color blendings of LED light were found to provide illuminated situations similar to halogens or fluorescent sources. These blendings were well accepted, and indeed often preferred, although the color rendering index (CRI) was always low. This indicates that the CRI as it stands is inadequate to characterize the color rendering of solid‐state light sources, and needs to be updated. LED‐based lighting systems seem to have considerable potential for use in shops and display units, where they may well outperform existing lighting systems. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 310–320, 2009     

A new approach for open‐end sequential change point monitoring

We propose a new sequential monitoring scheme for changes in the parameters of a multivariate time series. In contrast to procedures proposed in the literature which compare an estimator from the training sample with an estimator calculated from the remaining data, we suggest to divide the sample at each time point after the training sample. Estimators from the sample before and after all separation points are then continuously compared calculating a maximum of norms of their differences. For open‐end scenarios our approach yields an asymptotic level $\alpha$ procedure, which is consistent under the alternative of a change in the parameter. By means of a simulation study it is demonstrated that the new method outperforms the commonly used procedures with respect to power and the feasibility of our approach is illustrated by analyzing two data examples.     

Phase morphologies of vulcanized chlorobutyl rubber/polyamide 12 blends: The breakup of pre‐crosslinked CIIR phase

Dynamic vulcanization to prepare blended thermoplastic vulcanizates (TPV) is a kind of complicated blending technology, where the breakup of the rubber phase happens accompanying with the crosslinking of rubber. In this study, we aim to investigate the effect of crosslinking on the breakup of chlorobutyl rubber (CIIR) phase in thermoplastic polyamide 12 (PA 12) matrix by purposely using pre‐crosslinked CIIR with different crosslink degrees and plasticizer contents. Besides, the effect of blending conditions on the breakup of crosslinked CIIR phase was studied. The results show that a low crosslink degree, a high content of plasticizer, a low blending temperature and a morderate rotor speed of 70 rpm facilitate the breakup of pre‐crosslinked CIIR in PA 12 matrix. This is ascribed to the decrease in the modulus of pre‐crosslinked CIIR phase because of either a low crosslink degree or a high content of plasticizer, the increase in the molten viscosity of thermoplastic matrix because of a low blending temperature and a moderate rotor speed. It is indicated that the breakup of pre‐crosslinked rubber is mainly dominated by the modulus of crosslinked rubber phase as well as the molten viscosity of thermoplastic matrix and shear stress. This study will provide guidance for the preparation of CIIR/PA TPV. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40765.