Saturday, November 3, 2012

The Munsell Color Classification System [1-3]
Art Resource

Marie-Therese Wisniowski

This is the nineth blog in the "Art Resource" series, specifically aimed to construct an appropriate knowledge base in order to develop an artistic voice in ArtCloth. Other posts in this series are:
Glossary of Terms
Units Used In Dyeing And Printing Of Fabrics
Occupational, Health & Safety
A Brief History Of Color
The Nature Of Color
Psychology of Color
Color Schemes
The Naming Of Colors
Methuen Color Index And Classification System
The CIE System
Pantone - A Modern Color Classification System
Optical Properties of Fiber Materials
General Properties of Fiber Polymers and Fibers - Part I
General Properties of Fiber Polymers and Fibers - Part II
General Properties of Fiber Polymers and Fibers - Part III
General Properties of Fiber Polymers and Fibers - Part IV
General Properties of Fiber Polymers and Fibers - Part V
Protein Fibers - Wool
Protein Fibers - Speciality Hair Fibers
Protein Fibers - Silk
Protein Fibers - Wool versus Silk
Timelines of Fabrics, Dyes and Other Stuff
Cellulosic Fibers (Natural) - Cotton
Cellulosic Fibers (Natural) - Linen
Other Natural Cellulosic Fibers
General Overview of Man-Made Fibers
Man-Made Cellulosic Fibers - Viscose
Man-Made Cellulosic Fibers - Esters
Man-Made Synthetic Fibers - Nylon
Man-Made Synthetic Fibers - Polyester
Man-Made Synthetic Fibers - Acrylic and Modacrylic
Man-Made Synthetic Fibers - Olefins
Man-Made Synthetic Fibers - Elastomers
Man-Made Synthetic Fibers - Mineral Fibers
Man Made Fibers - Other Textile Fibers
Fiber Blends
From Fiber To Yarn: Overview - Part I
From Fiber to Yarn: Overview - Part II
Melt-Spun Fibers
Characteristics of Filament Yarn
Yarn Classification
Direct Spun Yarns
Textured Filament Yarns
Fabric Construction - Felt
Fabric Construction - Nonwoven Fabrics
A Fashion Data Base
Fiber Construction - Leather
Fabric Construction - Films
Glossary of Colors, Dyes, Inks, Pigments and Resins
Fabric Construction – Foams and Poromeric Material
Glossary of Fabrics, Fibers, Finishes, Garments and Yarns
Weaving and the Loom
Similarities and Differences in Woven Fabrics
The Three Basic Weaves - Plain Weave (Part I)
The Three Basic Weaves - Plain Weave (Part II)
The Three Basic Weaves - Twill Weave
The Three Basic Weaves - Satin Weave
Figured Weaves - Leno Weave
Figured Weaves – Piqué Weave
Figured Fabrics
Glossary of Art, Artists, Art Motifs and Art Movements

The Glossary of Terms, Timelines of Fabrics, Dyes and Other Stuff, A Fashion Data Base, Glossary of Colors, Dyes, Inks, Pigments and Resins, Glossary of Fabrics, Fibers, Finishes, Garments and Yarns and Glossary of Art, Artists, Art Motifs and Art Movements have been updated in order to better inform your art practice.

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Color is a critical component in creating art. It is not by accident that human beings can perceive color in the visible region of the electromagnetic spectrum. If our eyes were sensitive to infrared or ultraviolet radiation (which they are not) we could not perceive objects - such as food sources - from long distances, since in these regions of the electromagnetic spectrum the Earth's atmosphere is fairly opaque.

Many names are given to different colors, which makes it difficult for designers and dyers to reproduce the “exact” color of choice. For example, a particular hue of blue can be labelled as navy blue, delft blue, aquamarine, sky blue and azure. Hence it is difficult to: (i) readily identify a hue from a particular name; (ii) provide a formula or recipe, which would enable a particular hue to be reproduced consistently.

The object of any color specification system is not just to give a commonplace description of a color, but to specify that particular color accurately for reproduction. Today we shall explore the Munsell color specifying system, which was developed in 1915 by American Albert Munsell. It is a subjective color ordering system, which attempts to provide a precise nomenclature for colors. Using water-colors, he painted many hues on small square tiles of white paper and arranged these in the order that eventually became known as the Munsell system.

Albert Henry Munsell.

The Munsell Color Solid
Munsell used a three-dimensional color solid in order to arrange his color scheme. The solid, which is shaped like a spinning top or like the planet Earth, is pure black at the bottom and pure white at the top, with pure red, blue and green in equal intervals around the latitudes. Horizontally travelling around the circumference of the solid from left to right, blue tends to purple and then to red; red tends to yellow, which becomes green; and green tends to blue-green, which becomes blue. Thus each color in the Munsell scheme has three parameters – hue, chroma and value – which are represented by the three dimensions of solid.

The Munsell color solid.
Note: Space has dimensions of width, length, and height, whereas a Munsell color has dimensions of hue, chroma and value.
Courtesy of reference[2].

Cross section of the Munsell color solid.

A Munsell color chart consists of hundreds of small color rectangles, called color chips, which are arranged according to their hue, value and chroma. Each chip represents one specific color. Initially, Munsell subjectively judged the difference in color or the color interval between any two adjacent chips to be the same. Later it was found that more objective color measurements (via instrumentation) between any two adjacent chips resulted in little modification. Thus, it was deemed that any color could be quickly and easily identified using his three parameters of hue, chroma and value.

There are a total of 320 chips in this Munsell hue grid.

The advantage of the Munsell system over other subjective ordering systems is that it can accommodate and specify every color in existence and any new colors, which may be developed in the future. Its advantage over the objective CIE system is that the Munsell color charts allow visual examination of numerous colors.

Munsell Value Dimension
The Munsell value refers to the lightness or darkness of a color. It is represented by the vertical axis of the Munsell color solid (see above). The Munsell value scale ranges from black to white in eleven equal intervals with black having a zero value and white deemed to have a value of 10, with various greys in between having attributed values in between these two extremes. The intervals along the vertical scale are such that the visual difference between any two adjacent shades of grey are the same and so can be stepped one value higher or lower. The vertical value scale in the Munsell Color slide is often referred to as the trunk of the Munsell solid or tree.

Munsell value scale. Black is deemed to have a value of zero, whereas white has a value of 10.

Munsell Hue Dimension
The Munsell hue dimension can be thought of the latitudes of the Munsell color solid (or top). Munsell subjectively decided to base his charts on ten hues: five principal hues and five that are known as intermediate hues. Although these divisions are technically hues, they are also known in common usage as the Munsell colors.

Munsell relationship between chroma, value and hue.
Note: The hue dimension is the latitude of a Munsell color solid. As you go up the central axis the color lightens. As you circumnavigate the latitudes, the colors change into different hues. Going inward or outward, to and from the axis, the chroma must alter.

The figure below shows a disc whose ten equal divisions represent the ten Munsell colors, namely:
(i) Principal Munsell Colors – red (R), yellow (Y), green (G), blue (B) and purple (P).
(ii) Intermediate Munsell Colors – yellow-red (YR), green-yellow (GY), blue-green (BG), purple-blue (PB) and red-purple (RP).

Each of the ten areas of the disc in the figure is sub-divided into ten equal parts, with each part representing a color. The sub-divisions - one to ten - represent the principal and intermediate Munsell colors.

An explanation of the Munsell hue scale.
Courtesy of reference[2].

Munsell Chroma Dimension
The third dimension of the Munsell system is chroma, which refers to the purity, intensity, vividness, saturation or brightness of a particular color. The closer the color is to vertical or neutral axis (or the value scale), the duller the color (see figure above that shows the relationship between hue, chroma and value).

When represented on a disc, as in the figure below, chroma radiates outwards from the center in equal steps of two. Munsell chose a chroma difference of two, because this difference is more easily perceived by the human eye than a chroma difference of one, the latter of which is not easily differentiated.

Munsell chroma scale.
Courtesy of reference[2].

Specifying Color Using The Three Munsell Dimensions
In order to give a simple explanation of the Mansell hue and chroma scales, each were depicted above separately. However, to highlight why the Mansell color specifying system can take into account numerous colors, the figure below illustrates the numerous colors, which are possible in theory for any one of the value intervals ranging from 1 to 9. Note: On the value scale 0 is black and 10 is white.

Combined Munsell hue and chroma scales.
Courtesy of reference[2].

An examination of the Munsell color solid (shown above) highlights that the disc found along the value scale does not have equal diameters (similar to the latitudes of planet Earth). The diameter of the disc depends on its position on the vertical axis (i.e. value scale). The figure below, which is a cut away section of the Munsell solid, shows this more clearly.

Three-dimensional representation of the Munsell color solid.

The following steps specify a color using the Munsell color system. The example used is a slightly dark, bright, purple-blue color indicated by the asterisk in the figure below.

Munsell color chart for hue "Purple-Blue" (5PB) and "Yellow" (5Y) is given in the figure above.

The Munsell parameter description of the color represented by the asterisk (as seen in the black and white version) is as follows:
(i) The hue number is quoted first; for the example it is 5 (since all the squares on the left belong to this hue).
(ii) This is followed by a capital letter, which stands for the principal or intermediate Munsell color: for example PB = purple-blue.
(iii) The next step is to quote its value to indicate the lightness/darkness of the color; for this example it is 4.
(iv) The last step is to home in on the chroma number to indicte brightness/dullness of the color; for example in this case it is 8.

Thus, the slightly dark, bright, purple-blue color has been specified as 5PB/4/8. This means that quoting this specification automatically gives an unambiguous designation of this color and so it can be easily reproduced precisely.

Munsell Color Charts
The three-dimensional representation of the Munsell color solid shows that those hues near the value scale are represented by smaller and smaller wedge-shaped blocks. Munsell did not develop his color system using a solid, but arranged his color chips in the form of charts (see above).

The black and white version of Munsell’s color chart for purple-blue and yellow was produced as follows. Consider a sheet of paper, held standing on its edge, passing through any one of the diameters such as R to BG, G to RP, B to YR, Y to PB, or P to GY as shown in the figure below.

The first step in constructing a Munsell chart.
Courtesy of reference[2].

Consider that this sheet of paper extends the length of the value scale from 0 to 10. Now the Munsell color chart for purple-blue and yellow (see above) show the hues of two Munsell colors. The representation of two Munsell color on each chart was purposely selected since it has the advantages of being economical as well as indicating the hues that are opposite each other in the Munsell system.

In the Munsell color chart for purple-blue and yellow (see above), some of the rectangles have dotted lines. The dotted lines represent hues not yet developed but which may be developed in the future. The rectangles with solid lines are those already developed. The columns of rectangles represent the chroma scale and the rows of rectangles or color chips represent the value scale.

The Munsell system usually consists of about twenty charts, which together are known as the Munsell color atlas. Each of the charts has two Munsell colors, which lie on the same diameter. For example, purple-blue and yellow lie on the same diameter. The twenty charts are at 2.5, 5.0, 7.5 and 10.0 on the hue scale for each of the Munsell colors. There are therefore 960 different color chips in the atlas.

Charts in a Munsell student color set.

[1] A. H. Munsell, Book of Color 1942-1962, The Munsell Color Company, Baltimore USA (1963)

[2] E.P.G. Gohl and L.D. Vilensky, Textile Science, Longman Cheshire, Melbourne (1989).

[3] J. Long and J. T. Luke, The New Munsell Student Color Set, 2nd Edition, Fairchild Books (2001).

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