A theory of unique hues and colour categories in the human colour vision

A novel approach to assessing colour appearance is described. It is based on a new technique—partial hue‐matching—which allows for measuring colour in terms of component hues objectively, without resorting to verbal definitions. The new method is believed to have a potential to be as exact as colorimetric techniques. In contrast to classical colour matching, which implies visual equivalence of lights, partial hue‐matching is based on judgements of whether two lights that are different in colour have some hue in common. The major difference between classical colour matching and partial hue‐matching is that the latter is intransitive, whereas the former is generally believed to be transitive (though see Logvinenko, Symposium on 75 years of the CIE Standard Colorimetric Observer, Vienna, Austria, 2006). Formally, partial hue‐matching can be described as a reflexive and symmetric binary relation (i.e., tolerance). The theoretical framework of tolerance spaces is used for developing a theory of partial hue‐matching. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011     

Unique hue data for colour appearance models. Part I: Loci of unique hues and hue uniformity

Psychophysical experiments were conducted to assess unique hues on a CRT display for a large sample of colour‐normal observers (n = 185). These data were then used to evaluate the most commonly used colour appearance model, CIECAM02, by transforming the CIEXYZ tristimulus values of the unique hues to the CIECAM02 colour appearance attributes, lightness, chroma and hue angle. We report two findings: (1) the hue angles derived from our unique hue data are inconsistent with the commonly used Natural Color System hues that are incorporated in the CIECAM02 model. We argue that our predicted unique hue angles (derived from our large dataset) provide a more reliable standard for colour management applications when the precise specification of these salient colours is important. (2) We test hue uniformity for CIECAM02 in all four unique hues and show significant disagreements for all hues, except for unique red which seems to be invariant under lightness changes. Our dataset is useful to improve the CIECAM02 model as it provides reliable data for benchmarking. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2011     

Unique hue data for colour appearance models. Part III: Comparison with NCS unique hues

In this study, Swedish Natural Color System (NCS) unique hue data were used to evaluate the performance of unique hue predictions by the CIECAM02 colour appearance model. The colour appearance of 108 NCS unique hue stimuli was predicted using CIECAM02, and their distributions were represented in a CIECAM02 a_c–b_c chromatic diagram. The best‐fitting line for each of the four unique hues was found using orthogonal distance regression in the a_c–b_c chromatic diagram. Comparison of these predicted unique hue lines (based on the NCS data) with the default unique hue loci in CIECAM02 showed that there were significant differences in both unique yellow (UY) and unique blue (UB). The same tendency was found for hue uniformity: hue uniformity is worse for UY and UB stimuli in comparison with unique red (UR) and unique green (UG). A comparison between NCS unique hue stimuli and another set of unique hue stimuli (obtained on a calibrated cathode ray tube) was conducted in CIECAM02 to investigate possible media differences that might affect unique hue predictions. Data for UY and UB are in very good agreement; largest deviations were found for UR. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 256–263, 2015     

Unique hues and their stimuli—state of the art

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, 39, 279–287, 2014; Published Online 20 March 2013 in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/col.21793     

Unique hue data and CIECAM02: A comment on Xiao et al

This letter to the editor notes the offsets from the origin of unique hue loci in the recent article, Unique Hue Data for Colour Appearance Models. Part III: Comparison with NCS Unique Hues by Xiao et al. [Color Res Appl 2015;40:256–263] and suggests that modifications to the cone response function in CIECAM02 be explored. © 2015 Wiley Periodicals, Inc. Col Res Appl, 2015     

Experimental object color unique hue data for the mean observer for color appearance modeling

Color appearance models, among other things, predict the hue of a stimulus when compared with defined stimuli that represent the four unique hues. Recent studies have indicated that the stimuli representing with high reliability unique hue (UH) percepts vary widely for different color‐normal observers. The average yellow and blue UH stimuli for 102 observers, as determined in a recent experiment at medium chroma, differ considerably from the CIECAM02 defined unique hues, based on the Swedish NCS. Wide inter‐observer variability precludes color appearance models from accurately predicting, for individual observers, all four unique hue stimuli. However, models should predict accurately those of a well‐defined average observer. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 505–506, 2008     

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

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

Comparison of unique hue stimuli determined by two different methods using Munsell color chips

Unique hue stimuli were determined by male and female observers using two different visual experimental procedures involving Munsell color chips of varying hue but identical chroma and value. The hypothesis was that unique hues can be more reliably established by explicit selection from a series of ordered stimuli than implicitly by hue scaling a series of stimuli in terms of neighboring UHs and this was statistically confirmed. The implicit selections based on long term memory of UHs appears to have been more challenging to observers since variability was increased by nearly 50% compared to when UHs were explicitly selected. The ranges of unique hues selected in the two methods were, however, comparable and no statistically significant difference was found between the results of females and males. The intra‐observer variability in picking a stimulus to represent a unique hue, for all observers and averaged for all hues, was approximately 12% of the mean spread of unique hues, confirming that the large inter‐observer variability is driven by differences in color vision and perhaps cognitive processes. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010     

Global color impressions of multicolored textured patterns with equal unique hue elements

A global color impression from a multicolored textured pattern can be identified. It is not clear, however, how such a single color impression can be determined from the elemental colors of the multicolored textured pattern. To investigate this question, two hypotheses were evaluated. The first hypothesis is that a single color impression is determined by the colorimetric average of the elemental colors in the textured pattern (colorimetric average hypothesis). The second hypothesis is that the impression is influenced by the color appearances of the elemental colors in the textured pattern (color appearance hypothesis). Using an asymmetrical color matching method, the authors obtained single color impressions for random‐dot textured patterns consisting of two colors with the same unique hue and brightness but each with a different saturation. Our results showed that the matched colors were not located on the line connecting the two elemental colors of the pattern, but rather were on the curved unique hue loci line. Furthermore, the chromaticities of the matches shifted toward a higher saturation than the colorimetric averages. These results support the color appearance hypothesis and suggest that a single color impression from a multicolored textured pattern is determined by a mechanism that integrates the color appearances, i.e., hue, saturation, and brightness (or lightness), of the elemental colors in the pattern. In addition, it seems that the integration of the color appearances is not a simple process, because the apparent saturation of the color impression was higher than that of the colorimetric average and the average of the chromaticities of the colors in the pattern. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 267–277, 2007     

Principal hue curves and color difference

The size of perceptual difference of colors (j, k) is scaled as d_jk by selecting a pair of Munsell grays in which the lightness difference matches in size with the color difference. Hence, d is given in terms of Munsell V. The degree of principal hue component α in a color j is scaled as ξ_α(j) by making marks on a line segment and the range of ξ_α is from 0 to 10. By plotting ξ_α(H V/C) on Munsell H‐circle, principal hue curves ξ¯_α(H V/C) are defined, where α = R, Y, G, B, V = 4–7, and C = 2–10. In this process, similar plots of NCS codes (cϕ_α) are used as references. The curves ξ¯_α(H V/C) tell us the appearance of Munsell colors (H V/C) and also enable us to predict color differences. The relationship between d_jk and ΔV = |V_j − V_k|, Δξ¯_α = |ξ¯_α(H_j V_j/C_j) − ξ¯_α(H_k V_k/C_k)| is tested in various ways, e.g., logarithmic, power, Minkowski‐type functions. The best predictor d̃ is given by a simple linear form, d̃ = a_VΔV + {d₀ + Σa_αΔξ¯_α}. For 899 pairs (j, k), 706 differing in H, C and 193 differing in H, V, C, a_V = 0.459, d₀ = 0.610, a_R = 0.199, a_Y = 0.031, a_G = 0.098, a_B = 0.136, and the root‐mean‐squares of (d_jk − d̃_jk) is 0.338 in the matched V‐unit. © 1999 John Wiley & Sons, Inc. Col Res Appl, 24, 266–279, 1999     

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

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

奥司米韦中间体的合成工艺研究

以(-)-莽草酸为原料,经酯化、丙酮保护、甲磺酰化后,缩酮交换、还原开环、环氧化得到流感病毒神经氨酸酶抑制剂奥司米韦(Oseltamivir)的重要中间体(3R,4R,5S)-4,5-环氧基-3-(1-乙基丙氧基)-1-环己烯-1-甲酸乙酯,总收率46.4%。化合物的结构经IR、1HNMR、MS确证。该路线原料价廉易得、反应条件温和、危险性小、收率较高,适合于工业化生产。     

氮杂环丁烷类药物中间体的合成

以1-叔丁氧羰基-3-羟基氮杂环丁烷为原料,叠氮化钠和邻苯二甲酰亚胺钾盐为氨源,考察了两种途径合成1-叔丁氧羰基-3-氨基氮杂环丁烷这种药物中间体实验的可操作性、安全性能、产率高低和后处理的繁简。实验表明,当用叠氮化钠为氨源取代羟基成叠氮基时,经过分批加入锌粉可还原成伯氨,得到70%的产率。但是叠氮化钠毒性较强,受热或震动摩擦可发生爆炸,操作难度较大。当用邻苯二甲酰亚胺钾盐为氨源,生成的叔氨在乙醇水合肼溶液中加热回流肼解生成伯氨,产率为63%。产率虽然低于前一种方法,但是实验的可操作性很强,安全且后处理简单。     

去甲基文拉法辛中间体的制备方法

以4-[2-氨基-1-(1-羟基环己基)乙基]苯酚为原料,经氨基保护、缩合、水解、甲基化得到去甲基文拉法辛中间体,总收率在64.8％,色谱纯度99.5％以上,操作简单,副产物少,适合工业化放大.     

莫西沙星中间体的合成

本文以2,3-吡啶二羧酸为原料,依次经过环合、还原吡啶环及羰基、拆分和氢解脱苄基得到莫西沙星的中间体(S,S)-八氢-6H-吡咯并[3,4-b]吡啶,总收率44.1%。     

建筑中水工程应用及若干问题讨论

建筑中水对为缓解北方城市水资源短缺提供了一条途径,本文根据工程实例,讨论了建筑中水工艺中的几个技术问题,以供设计、运行和管理参考。     

The unique characteristics of water in chitosan–polyether semi‐IPN hydrogel

The state and mobility of water in crosslinked chitosan–polyether semi interpenetrating network (IPN) (cr‐CS–PE semi‐IPN) was studied using differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR), respectively. The effect of water content on free volume for water in gel network was investigated by positron annihilation lifetime spectroscopy (PALS) and its effect on the diffusion coefficient are discussed as well. The results show that with the increase of water content, the mobility of water molecules and the free volume of hydrogel network are enhanced. In the following free‐volume diffusion equation: D = Aexp(−B/V_f), A and B are not constant but are considered as the functions of water contents. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 449–453, 1999     

Changes in hue and saturation of chromatic lights presented in the peripheral visual field

The perception of ten different colors on a CRT display presented across the horizontal meridian of the visual field were measured to determine the range of relevant test stimuli for color zone map measurement. Hue and saturation judgments were used based on the opponent‐colors theory. The changes of the unique hue components for eccentric displays of red, yellow, green, and blue fall within the distribution range of previous results obtained using monochromatic lights. Chromatic displays of nearly unique hues with high saturation would be significant as test colors for measurement for a color zone map. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 413–424, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10194     

液态尤里卡沥青在槽罐运输中挂壁特性研究

通过特定组分条件下尤里卡沥青在槽罐中的反复充装试验 ,研究液态尤里卡沥青在槽罐运输中可能的结壳情况 ,观察尤里卡沥青在槽罐运输过程中的温度损失规律 ,以及沥青在槽罐中停留时间与沥青残留量的关系 ,为液体沥青槽车的订货提供依据。