Munsell system

It is desirable for the record to have an objective statement of the nature and degree of color deterioration. The simplest, but least desirable, method is comparison of sample color with color charts or plates such as those used in the Munsell system, Ridgeway s color standards, or the Maerz and Paul dictionary of color. Such a method is limited in value because of the difficulty of obtaining true color matches, and because of variations due to human error. The use of color charts or plates may be much improved in the Munsell system by employing a disk colorimeter (29). Kramer and Smith (21) have pointed out that the results obtained in its application to foods are sometimes difficult to explain and compare, and that the method requires special training of the operator and is tedious and cumbersome. 

Nevertheless, it is well to note that it was the subjective observation of the lack of correction for luminosity in the Munsell System that gave impetus to the development of the CIE Color System. The major problem vidth the Munsell system was that each person attempting to match colors did not produce the exact same result. So color matching became dependent upon the person. 

When Munsell devised his color space, he did so on the basis of minimum observable color perception steps. But the problem with the Munsell System was one of reproducibility, which the CIE Standard Observer cured. In formulating a color match, one wants to be able to predict the correct concentration of colorants required, whose scattering and absorption properties are known, i.e.- the lightness, so as to match the sample submitted, starting with their spectrophotometric curves. In practice, this is not so simple, since two colors must have identical spectrophotometric curves to be exactly equal. It turns out that the human eye will identify the two colors to be equal if their spectrophotometric reflectances are reasonably close. Two colors may appear to be equal under Daylight illumination, but quite different under incandescent lamp illumination. These colors are known zus "metamers" and the phenomenon "metamerism". 

Figure F5.1.1 The Munsell system describes color in terms of hue, value, and chroma. Figure courtesy of GretagMacbeth. This black and white facsimile of the figure is intended only as a placeholder for full-color version of figure go to http //www.currentprotocols.com/colorfigures...

The Munsell system provided a model for easily identifying a color. 

Today the Munsell system is widely used as a standard for color identification and is so recognized in the fields of science and industry. (See Figure 1.6.)... 

Adams-Nickerson (AN) system, well known for many decades and derived from the Munsell system, was recommended for pigment testing by DIN (German Standards... 

In contrast to the patchwork-like Munsell system, the CIE system and its modifications (developed by the International Commission on Illumination, CIE, in 1931) create numerically continuous color spaces. They are based on the principle of tricliromaticity of vision which states that the... 

Note that the uniformity of a color space is of concern only if color is regarded as a (visual) quality. When using color as an analytical tool, the color system which differentiates the iron oxides most effectively would be the most favorable, no matter whether it is uniform or not. A discriminant analysis performed with a large number of iron oxide samples showed that CIE-Yxy, CIE-Lab, and the Munsell system performed equally well (Scheinost and Schwertmann, 1999). Therefore, the choice of a color system is not crucial. Furthermore, computer programs are available which transfer colors from one system into another. More details on color theory and color systems are given by Wyszecki and Styles (1982) and Hunter and Harold (1987). 

The Ostwald classification has been replaced by the Munsell system, which leaves spaces to accommodate pigments of greater brightness than have hitherto been made. The three basic attributes used for the description and location of colours are value, hue, and chroma. 

Fig. 3.4b), known as CIELAB, has generally replaced the Hunter space for industrial applications although this has been somewhat slower in parts of the food industry where methods established on the Hunter system have economic reasons for its continued use. The improvements in CIELAB are due to the nonlinear cube root transformation of the 1931 tristimulus values, which more approximate the visual spacing of the coloured samples in the Munsell system. The formulae are... 

What we should get is a circular spacing of the ten Munsell colors, if the Munsell system is truly accurate in regard to the luminosity factor. However, they are not. On the CIE diagram, the spacing is considerably distorted. Since we already know the CIE method to be corrected for the luminosity factor, the conclusion is obvious. In 1920, Priest showed that if the Munsell-Chips were viewed on a white-background, the "brightness", i.e.- lightness as viewed by the human eye, could be related to the Munsell system by ... 

The Munsell system arranges color samples according to a definite systematic process. The differences between the individual colors have been revised many times over the years the improved system is known as the Munsell Renotation System. Two different MR systems are used, one for glossy, the other for mat surfaces. 

In contrast to the Munsell system, the CIE system does not use color samples. The CIE system is based on the Grassmann laws, which state that a color valency is completely described by the sum of the vector products of three color values and their color value proportions ... 

The CIE system, however, is not a metric sensitivity system, that is, color separations are not equally large for equally large sensitivity differences. The human eye has a maximum sensitivity at 555 nm, and often sees a certain color displaced from rather than at the absorption spectrum maximum. The CIE system and the Munsell system are not directly interconvertable for this reason. The shade of the Munsell system, however, corresponds to a ray coming from the neutral color point for the wavelength of the same color shade in the CIE system. The chroma of the Munsell system can be assigned to the spectral color proportions of the CIE system which are given as... 

Values of hue-angle and chroma can be similarly calculated for CIELAB space. Both the CIELUV and CIELAB spaces approximate to the Munsell system for the uniform spacing of colored samples of painted papers. 

We can experience very many just noticeable differences (JND s) of color. The JND, also known as the difference threshold or discrimination threshold, is the smallest change in any physical stimulation that can be observed with the unaided senses. There are a number of models and systems to standardize or predict resultant hues from mixtures of colors. Most notable of these are the standards of Ridgeway (1912), Munsell (1929), and various modifications of the Munsell system as found in the ISCC-NBS method of designating colors (Kelly and Judd, 1955), A Universal Color Language (Kelly, 1965) and the National Bureau of Standards (NBS) special publication 440, "Color. .. Universal Language and Dictionary of Names" (Kelly and Judd, 1976). There are more than 13000 color names in the NBS Special Publication 440. 

Color notion n. Orderly system of numbers, letters, or a combination of both, which serves to describe the relationship of colors in three-dimensional space. Thus, three dimensions must be included for example, hue, value, and chroma of the Munsell System. Single dimensional notations, such as a yellowness sale, can be used only if the other two dimensions are fixed or described two-dimensional notations can be used only if the third is fixed or described. See color order systems. 

Color order systems n. Systems used to describe an orderly three-dimensional arrangement of colors. Three bases can be used for ordering colors (1) an appearance basis, i.e., a psychological basis in terms of hue, saturation, and lightness - an example is the Munsell System (2) an orderly additive color mixture basis, i.e., a psychophysical basis - examples are the CIE System and the Ostwald System and (3) an orderly subtractive color mixture basis - an example is the Plochere Color System, based on an orderly mixture of inks. 

Sanderson-Milner zeta space color difference equation n. A color difference equation designed to fit the spacing of the Munsell system and based on Munsell value functions as described in the Adams chromatic value color difference equation ... 

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