Munsell Colour System

There is a variety of systems used to quantify colour and to assist in the comparison of colours, two important ones being the CIE-Lab system and the Munsell colour classification. Details of these systems are given in Wyszecki Styles (1982) and Heine Volz (1993). Very briefly, the GIF systems are based on the principle of tri-... 

In soil and other geosciences, colour is commonly measured using the Munsell colour classification system. This system defines colour in terms of hue H (position of colour in the spectrum), chroma C (the purity of the hue going from the grey to the pure colour) and value V (the lightness of the colour on a scale ranging from black to white). The reflectance measurements can be converted into the characteristic parameters or coordinates of the different measurement systems. 

In terms of the Munsell hue (see Chap 6) the colour of red beds varies usually between 5YR-2.5YR (reddish-brown to red), but may also extend into 10RP-7.5RP (red-purple). A more detailed colour measurement using the CIE D a b system places the red beds within a space encircled by a range of synthetic hematites of different crystal sizes, as seen in Figure 15.2. This makes it likely that the colour of red beds is determined by hematite. 

The Ostwald classification has been replaced by the Munsell system, which leaves spaces to accommodate pigments of greater brightness than have hitherto been made.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. 

The Munsell chart and Ostwald s system are not all that might be desired because their construction and use are not free from subjective elements they have other limitations such as lack of permanency of the colour standards. In 1931 the Commission Internationale de I Eclairage, usually referred to as the C.I.E., recommended what is known as the C.I.E.. system for numerical specification of colour. The foundation on which the method was based was the colour triangle illustrated in Fig. 26.9. It is assumed that the corners of an equilateral triangle are illuminated by the... 

Use a tape measure to allow the recording of depths and hence the thicknesses of the soil horizons in the profile. Colour is used to identify the different horizons within the profile. Standardized descriptions of colour can be obtained by the use of the Munsell Soil Colour Chart System (see Chapter 1). 

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... 

Each colorimeter system uses different coordinates, yet all can be compared to the colour set X, Y, Z used by the International Commission on Illumination and Munsell systems (Moore and Janick 1983). 

Munsell System. A method of colour notation based on evaluation of three parameters lightness, hue and saturation. (A. H. Munsell, A Colour Notation, Munsell Color Co., Inc., Baltimore, USA.)... 

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