Locating basic colours in the munsell space

This experiment extends the work of Boynton and Olson by providing a replication of their OSA studies, but using the Munsell system. It aims to define the location of the eleven basic surface colours within Munsell space using a monolexemic colour naming technique, and to improve sampling from the red and neutral regions. A comparison of the Munsell and OSA results reveals that while the centroids obtained using the two systems correspond reasonably well, the Munsell focal samples have a much higher saturation than their OSA counterparts. This is undoubtedly due to the more restricted range of the OSA system and calls into question the status of the focal samples previously identified. the existence of Berlin and Kay's eleven basic colour categories is confirmed and their locations identified within Munsell colour space.     

A residual modified transformation formula from munsell to sRGB color system

A residual modified transformation formula from Munsell to sRGB color system is presented in this article. The development of the transformation formula is based on the 1625 Munsell color chips in the Munsell Renotation Data that could be displayed on the sRGB monitor. The developed transformation formula consists of two models, one is named as the corresponding matrix model and the other is the residual modified model. The corresponding matrix model was obtained using numerical analysis methods to map each chip color attribute values from Munsell to sRGB and then its corresponding matrix for each Hue was constructed. The residual modified model was obtained using the discrete cosine transform to construct a residual modified function, which was used to modify the transformation error of each chip after applying the corresponding matrix model. The transformed accuracy rate for the corresponding matrix model is 88.4% and for the residual modified model can be enhanced to 96.6% for all of the chips. The developed transformation formula can be applied to research in which Munsell colors are presented on the sRGB monitor. With the aid of these formulas, designers can show the advanced real‐time results on a sRGB monitor for the product's color planning based on Munsell color system. Therefore, this research has a great contribution on the practical application for color planning in product design. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 243–255, 2015     

Implications of standard states and ideal solution in terms of Raoult's law

Traditionally, Raoult's law has always been considered to describe the vapor-liquid equilibrium of ideal solutions. This treatment not only is awkward but also is not in complete agreement with the definition of an ideal solution in the sense of the Lewis-Randall rule. In this study, the characteristics of a model system of Raoult's law are analyzed. The analysis is based on the application of the Lewis-Randall rule in which the actual states of the pure components are used as the standard states. It is shown that, in the region where vapor-liquid equilibrium exists, neither the vapor nor the liquid is an ideal solution in the strict sense of the Lewis-Randall rule.     

Why does the CIELAB a* axis point toward magenta instead of red?

Red is a basic color. The work of Kay and Berlin on the evolution of color names in languages shows that, after white and black, red is the most basic of color terms. Red plays a key part in Hering's color opponent theory, and is one of the elementary colors in both the Munsell Color system and in the Natural Colour System (NCS). The CIELAB color system has an axis which is sometimes referred to as the red-green axis. But unique red is about 25° degrees counterclockwise from the positive a* axis. This article answers the question of why this is.     

Correlations between color attributes and children's color preferences

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, 39, 452–462, 2014     

Comparison of methods of parameric correction for evaluating metamerism

In practice, most metameric pairs do not achieve colorimetric equality for a set of reference conditions. These parameric pairs are composed of a residual color difference and a metameric difference. Three techniques have been used to correct this residual color difference: an additive correction in L*a*b*, a multiplicative correction in XYZ (recommended by the CIE), and parameric decomposition where the batch's spectrum is adjusted. Parameric decomposition can be viewed as batch correction using three “colorants” (process primaries) where the color‐mixing model is linear in reflectance. Most often, Cohen and Kappauf's Matrix R technique is used where the primaries are color matching functions. Alternative primaries were derived from a Munsell Book of Color and an automotive paint system using principal component analysis (PCA) and independent component analysis (ICA). 1,152 parameric pairs about 24 color centers were synthesized using the paint system and Kubelka–Munk turbid‐media theory. Each parameric pair was corrected to a metameric pair using these methods. Spectral accuracy was evaluated by comparing the corrected spectra to metameric reference spectra calculated using Kubelka–Munk batch correction. The Matrix R technique had the worst spectral accuracy under the reference conditions while both PCA and ICA had similar and reasonable accuracy. The special index of metamerism, change in illuminant, was calculated for each parameric pair using these various correction techniques to achieve colorimetric equality. The Matrix R and CIE‐recommended multiplicative techniques were statistically significantly worse than parameric decomposition using Munsell Book of Color PCA and ICA and automotive ICA process primaries. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 293–303, 2007     

Measuring color-matching functions. Part II. New data for assessing observer metamerism

The Munsell Color Science Laboratory model and visual colorimeter for collecting color-matching-function data were described in Part I of this article. The model and instrument have demonstrated results that correlate well with data collected using the National Research Council of Canada's Trichromator. Color-matching-function data for 18 observers and 20 repetitions on a single observer have been obtained using the Munsell Color Science Laboratory visual colorimeter. The variability for the single observer for 20 repetitions over a month's time was found to be similar to the uncertainty of matching within a single measurement session. The variability of the 18 observers was found to be much larger. The results were compared with the CIE Standard Deviate Observer. The variability of the CIE Standard Deviate Observer was on the order of the single observer variability while the multiple observer variability was significantly larger.     

A structural comparison of the Munsell renotation and the OSA–UCS uniform color systems

A structural comparison has been made of the lightness, chroma, and hue scales of the Munsell system, as expressed in the Munsell Renotations, and of the OSA‐UCS system. While the lightness scales are similar (except for the adjustment for the Helmholtz–Kohlrausch effect and the inclusion of a “crispening” effect in OSA–UCS), there are significant differences in the chroma scales along the major chromatic axes. Unlike in CIELAB, the increments in X and Z along these axes for equal chroma steps in both systems do not fall on a continuous function. In the two systems, as well as in CIELAB lines connecting colors of equal chroma differences at different Y values point to nonreal origins. These differ among the three systems. A major difference between Munsell and OSA–UCS is the size of the first chroma step away from gray. An experiment has been performed with the result that the OSA–UCS system is in much better agreement with the average observer in this respect than the Munsell system. OSA–UCS exhibits considerably more internal uniformity in terms of X and Z increments between steps than the Munsell system. © 2000 John Wiley & Sons, Inc. Col Res Appl, 25, 186–192, 2000     

Soret Diffusion and Non‐Ideal Dufour Conduction in Macroporous Catalysts with Exothermic Chemical Reaction at Large Intrapellet Damköhler Numbers

The adiabatic temperature rise in catalytic pellets is predicted from a modified version of the Prater equation. Onsager reciprocal relations for coupled heat and mass transfer are violated in an analysis of thermal diffusion in macroporous catalysts with exothermic chemical reaction when Dufour conduction (i.e., the diffusion‐thermo effect) is neglected. In this contribution, Dufour conduction is analyzed for both ideal and non‐ideal pseudo‐binary gas mixtures that simulate the production of methanol from carbon monoxide and hydrogen. In the diffusion‐controlled regime at large intrapellet Damköhler numbers where intermolecular collisions provide the dominant resistance to mass transfer within the catalytic pores, temperatures in the catalytic core could be much greater than predictions based on the original Prater equation when the Prater number exceeds 0.30. The molecular flux of thermal energy includes Fourier's law, the interdiffusional flux, and Dufour conduction. Diffusional mass flux includes Fick's law and the Soret effect. All physicochemical properties of the reactive gas mixture exhibit temperature dependence. There is essentially no difference between maximum intrapellet temperature predictions that include or neglect ideal Dufour conduction when external catalytic surface temperatures range from 300‐400 K and thermal diffusion enhances the flux of “smaller” reactants toward the centre of the catalyst. For “large‐molecule reactants” that participate in exothermic reactions, thermal diffusion opposes Fick's law and Dufour conduction opposes Fourier's law. Under these conditions, it is demonstrated that core temperatures are overestimated by neglecting both off‐diagonal coupling mechanisms (i.e., Soret diffusion and Dufour conduction). Prater numbers greater than unity and unrealistically high gas pressures are required to distinguish between maximum intrapellet temperatures for ideal and real gas simulations, where the latter consider two‐body interactions for Lennard‐Jones molecules in the virial equation of state.     

Geometric invariants under illuminant transformations

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, 39, 179–187, 2014     

Addition of carbon black NIR absorber to galvanised steel primer systems: Influence on NIR cure of polyester melamine topcoats and corrosion protection characteristics

Near infrared (NIR) is becoming a popular option for rapid cure of coatings in the coil coating industry particularly where fast line speeds are required. The technology has the potential to reduce the cure time of a 20 μm polyester coating on a galvanised steel substrate from around 30 s via conventional heating methods down to <10 s under the lamps. Previous work suggested that the ideal situation in this case is to have a topcoat which is slightly transparent to NIR and an absorbing substrate to heat the coating from the substrate outwards in a two stage process which separates solvent removal from cross linking and film formation. This can be taken further by tinting the primer layer with a pigment that absorbs in the NIR region. In this study spectroscopy was used to show that a coated steel system could appear white in the visible region because of the reflectance of TiO₂ but the NIR absorption could be altered by adding absorbing pigments such as carbon black. Lamp settings could be reduced by 20% to achieve equivalent cure with tinted primer systems. The potential degradation in corrosion protection afforded by carbon-black containing pigments at various loadings was assessed for model organic coatings applied to galvanised steel specimens. In situ scanning Kelvin probe studies showed that rates of corrosion-driven coating delamination by cathodic disbondment remained unchanged by pigment loadings of up to 3.5 wt%.     

Colorimetric study of SCOTDIC colour specifier

In this study, SCOTDIC cotton standard colours (a physical exemplification of the Munsell system) were studied extensively. L*, a*, b* values were measured and plotted to check the uniformity of the Munsell (SCOTDIC) hue, value and chroma values in a CIELAB diagram. Although for some borderline hues the hue angles were quite different than expected (around 0° or 360°), the correlation between SCOTDIC hue and CIELAB hue angle was fairly good and the correlation between SCOTDIC value and CIELAB lightness was also quite high. However, the correlation between SCOTDIC chroma and CIELAB chroma was only moderate. In the CIELAB diagram, the constant SCOTDIC hue and constant chroma loci took the shape of approximately linear radial lines starting from the origin and approximately concentric circles with the origin as their centres, respectively. However, some deviations were observed for high chroma colours and yellow hues in the respective cases. The instrumentally predicted Munsell notations were compared with the actual SCOTDIC notations. Some deviations of the SCOTDIC system from the Munsell system were observed.     

Hue scale adjustment derived from the Munsell system

Hue scale adjustment factors have been determined for CIELAB using the Munsell system. They have been found to vary significantly as a function of hue angle. A formula has been derived based on the 2° observer color‐matching functions that models the chroma scale of the Munsell system much more accurately than CIELAB using the same opponent color relationships. In this formula, hue differences can be calculated from hue angle differences, hue scale adjustment factors, and chroma. The hue scale adjustment factors based on hue angle required for the Munsell system have been derived. The variability by hue angle of these factors is such that an analytical hue scale adjustment function as those in CMC or BFD appears insufficient. The adjustment factors are compared to those recently derived by Qiao and coworkers. © 1999 John Wiley & Sons, Inc. Col Res Appl, 24, 33–37, 1999     

The primary hue circle

Munsell started to base his color-order system on measured physical quantities, but it came to represent the order of colors us they ure perceived. The hue circle represents fundamental facts about color vision. The Munsell hue circle has anomalous placement of blue and the use ($five principal hues does not relate to color vision nor applied color science. A reoriented hue circle, labeled with the additive and subtractive primariesblue,green, red, yellow, magentu, and cyan-but retaining the existing Munsell hue spacing and sectors is proposed.The primury hue circle relates to vision and color-reproduction processes, so it should exert a unifying influence on color .science. 0 1993 John Wi1ey . & Sons. Inc..     

LNZL水泥厂2500t/d生产线的热工检测与分析

对LNZL水泥厂2500 t/d生产线进行热工标定并分析,该厂熟料产量超过设计产量28.96％,达到3224.1t/d.系统烧成热耗为3302.6kJ/kg熟料,低于全国平均水平,一级筒出口温度为334℃,稍有些偏高;系统的分离效率为91.49％,出预热器飞灰量偏高,还有明显的改善空间.篦式冷却机效果欠佳,直接影响了熟料质量和余热发电量,热回收效率也偏低.该生产线系统还有比较大的潜力,如经过改进和优化,熟料产能还有可能进一步提高,热耗及电耗均可明显下降.     

Hue uniformity and the CIELAB space and color difference formula

The hue uniformity of the CIELAB system is investigated using a hue circle of Munsell colors at value 6 and chroma 14 and experimentally determined hue coefficient data. CIELAB hue differences for equal Munsell hue increments are found to vary up to nearly a factor 4, and hue coefficients differ from the experimentally determined ones by up to 40% at certain wavelengths. Dominant wavelengths assigned by the CIELAB system to individual Munsell hues are found to vary up to 35 nm from those of the Munsell Renotations. Four other color space systems are compared with widely differing but comparable results. The CIE 2° color-matching functions are adapted to result in a set of opponent-color functions accurately representing the Munsell Hue and Chroma data. A call is made for the experimental determination of the “standard hue observer” as a step toward an improved color space/color-difference formula. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23, 314–322, 1998     

Forgotten pioneers of color order. Part I: Gaspard Grégoire (1751–1846)

Some 100 years before Albert Munsell developed his color order system, French silk merchant and inventor of a technology for producing works of art in silk velours, Gaspard Grégoire, introduced a color order system based on the color attributes hue, (relative) chroma, and lightness. Conceived in the mid‐1780s, an atlas with 1350 samples was produced before 1813 and found use in French Royal manufacturing operations and educational institutions. It was followed a few years later by one with 343 samples. Grégoire's work was subsequently overshadowed by Michel‐Eugene Chevreul's more complicated and less intuitive hemispherical system of 1839. © 2007 Wiley Periodicals, Inc. Col Res Appl, 33, 5–9, 2008     

Protic ionic liquids for the selective absorption of H2S from CO2: Thermodynamic analysis

The solubilities of H₂S and CO₂ in four protic ionic liquids (PILs)—methyldiethanolammonium acetate, methyldiethanolammonium formate, dimethylethanolammonium acetate, and dimethylethanolammonium formate were determined at 303.2–333.2 K and 0–1.2 bar. It is shown PILs have higher absorption capacity for H₂S than normal ionic liquids (ILs) and the Henry's law constants of H₂S in PILs (3.5–11.5 bar at 303.2 K) are much lower than those in normal ILs. In contrast, the solubility of CO₂ in PILs is found to be a magnitude lower than that of H₂S, implying these PILs have both higher absorption capacity for H₂S and higher ideal selectivity of H₂S/CO₂ (8.9–19.5 at 303.2 K) in comparison with normal ILs. The behavior of H₂S and CO₂ absorption in PILs is further demonstrated based on thermodynamic analysis. The results illustrate that PILs are a kind of promising absorbents for the selective separation of H₂S/CO₂ and believed to have potential use in gas sweetening. © 2014 American Institute of Chemical Engineers AIChE J 60: 4232–4240, 2014     

Methods for generating spectral reflectance functions leading to color-constant properties

The Munsell color order system was rigorously defined for illuminant, observer, and surround. Using Nayatani's nonlinear model of chromatic adaptation, approximately colorconstant 1931 CIE tristimulus values for the notations of the Munsell Book of Color were calculated for a variety of continuous-spectrum illuminants between CIE A and 7600 K daylight. Several linear-programming models were devised for generating spectral reflectance functions that integrate to these tristimulus values. The most successful of these was a model based on an approximate-hue vector in tristimulus space, in which movement off and along this vector was restricted. Restrictions were also applied to the rate of change of reflectance with wavelength, following Ohta, and the model led to relatively smooth curves, comparable to those of real colorants. Indices of color constancy were devised to estimate the accuracy of the predictions. Comparisons with actual reflectance functions from physical samples revealed, in most cases, an improvement in color constancy and hue constancy.