Color Principles

Reexamining The Color Circle

T E X T
INTRODUCTION
Color perception is associated with light and the way it is reflected. Our perception of color changes when a light source is modified, or when the surface that reflects the light is stained or coated with a different pigment.

It is far easier to apply color pigments to a surface than to replace or modify a light source. Today, color pigments take many forms, come ready to use, and can be manipulated to create a variety of desirable effects.

The length of this text precludes extensive discussions of all color systems and theories. I shall therefore concentrate on color principles that relate to phenomena that can be obtained with color pigments and a stationary light source [the sun], providing consistent illumination by which all reflected colors are judged.

Theories are elaborated only as far as they are necessary for the development of a personal color sense. I do not try to advocate a single color system, although my analysis often echoes some theories of the great American colorist, Albert H. Munsell. I have based my basic color circle on Johann Wolfgang von GoetheÍs, an eminent German poet of the late 18th and early 19th centuries, who made important discoveries in the realm of color. I have also tried to reexamine the color circle by comparing our traditional notions of certain colors to recent scientific discoveries.

Illustrations in this part include diagrams as well as many designs created by students, which illustrate the points raised in the text. [Note: These splendid illustrations from the original text are not included here.] [p. 25]

BLACK AND WHITE
Black, the darkest possible color, is most effectively applied to a surface, as it obliterates what originally covered it. White, the lightest possible color, is also opaque, but must be applied thickly in order to cover a surface. It is ideal, however, as a surface for receiving colors, for it can show the faintest stains and does not distort colors, though it slightly darkens them. Neither black nor white can be produced by mixing other pigments.

Black and white used together create the greatest tonal contrast with maximum legibility and economy of means. They are therefore ideal for sketching, drawing, writing, and printing. In most instances, black makes the mark, and white is the surface, accounting for the tendency to read black shapes as positive and white shapes as negative spaces.

Since we are move accustomed to black images on a white background, reversing the two colors suggests something unreal, sometimes creating a dense or heavy design. [p. 26]

Flat Tones with Black and White
A uniform texture can be made with black on white or white on black, resulting in a flat tone that is either light or dark, depending on the proportion of black to white areas in the combination.

The same effect can also be achieved with fine black-and-white patterns, consisting of a regular arrangement of tiny planes, lines, or points.

[Examples show] the black-and-white elements are optically mixed and perceived as gray. [p. 27]

Tonal Transitions with Black and White
A black-and-white pattern consisting of lines or points can show a gradual change in density, subtly lightening or darkening the pattern from one part to another. A black-and-white texture, not necessarily as regular as a pattern, can produce a similar effect.

Although illusions of volume and depth can be achieved with black and white producing flat tones, much finer illusory effects are obtained with varying densities creating complicated areas of tonal transitions. [p. 28]

NEUTRAL COLORS
Mixing black and white pigments in varying proportions produces a range of grays. These grays together with black and white are referred to as neutral colors.

Although numerous steps of gray are possible, it is simpler to create only nine and arrange them into three groups.

a. The dark gray series consists of:
l - extremely dark gray [90% blackness]
2-very dark gray [80% blackness]
3--dark gray [70% blackness]

b. The middle gray series consists of:
4--dark middle gray [60% blackness]
5--middle gray [50% blackness]
6--light middle gray [40% blackness]

c. The light gray series consists of:
7--light gray [30% blackness]
8--very light gray [20% blackness]
9--extremely light gray [10% blackness]

These nine steps provide a basis for the accurate systematization of colors., A chart comprising the steps is called a gray scale. Black and white are not shown, because the scale provides light-dark comparisons to various colors, and no color is as dark as black or as light as white. Black can be given the number 0, meaning the total absence of light, and printed with 100% blackness, and white the number 10, meaning the maximum amount of light, and printed with 0% blackness.

This standard scale is a guide to visual thinking. Judging values with the naked eye can be inaccurate, since we tend to distinguish more gradations in the range of light grays than dark grays.

To obtain the grays that constitute the scale, black and white pigments can be mixed in varying proportions. The gray scale [example] was produced with a mechanical device and features machine-printed halftones; black and white pigments were not physically mixed. [p. 29]

Specific Keys of Neutral Colors
Grays are far more effective in suggesting depth and volume than black and white, which must be applied as textures and patterns to express the densities and weights of shapes and areas.

The terms high key, intermediate key, and low key denote particular tendencies toward specific effects. The application of neutral colors can be limited to a particular key, which emphasizes one portion instead of the entire scale.

High key describes a general lightness in the tonal expression of a design and stresses the light-gray series extending to white.

A design that exclusively features white and light grays creates a sense of mistiness and overall softness.

Some darker grays can be introduced for contrast, distinguishing between the expressed forms. This, however, cannot be overdone or the high-key effect will be destroyed.

Neutral colors in an intermediate key are, for the most part, in the middle-gray series. A design that is restricted to middle grays often lacks sparkle. A small amount of light and dark gray can add variety to the design.

Effective use of the intermediate key results in a well-balanced, intelligible composition.

Dark grays predominate in a low-key design, featuring the shades of gray in steps 1, 2, and 3 of the scale illustrated [example]. The design can also include transitions between these grays as well as black.

Shapes in a low-key design can be articulated and contrast introduced by adding lighter grays. This must be done subtly if the effect of a low-key design is to be maintained. [pp. 31,32]

Chromatic Colors
Our common notion of color refers to the chromatic colors, which relate to the spectrum as can be observed in a rainbow. Neutral colors are not part of these and can be referred to as achromatic colors.

Each chromatic color can be described in three ways. Hue is the attribute that permits colors to be classed as red, yellow, blue, and so on. The description of a hue can be more precise by identifying the colorÍs actual inclination from one hue to the next. For instance, a particular red may be more accurately called orange-red. Different color systems use different codes to describe colors made up of letters, numbers, or a combination of the two.

Value
Value refers to the degree of lightness or darkness in any color. A color of known hue can be more Accurately described by calling it either light or dark. For instance, a red is said to be light red if it is lighter than our notion of a standard red.

Chroma
Chroma indicates the intensity or purity of a color. Colors with strong chroma are the most brilliant, most vivid colors that can be obtained. Colors with weak chroma are dull; they contain a large proportion of gray.

[Example] shows the three aspects of color--hue, value, chroma--as three dimensions of a color cube. These also resemble the letter Y in the illustration: the vertical stroke is the extension in value; the upper-left stroke is the extension in hue, and the upper-right stroke is the extension in chroma. The color swatches immediately surrounding the center Y are identical [a green hue of middle value and strong chroma]. The colors move from green to yellow in the hue extension, from middle to dark in the value extension, and from brilliant to dull in the chroma extension. [p. 33]

VALUE
The first step in the exploration of color is to use all the possible variations of a single hue. As we have seen [in example], by manipulating its value or chroma, a single hue can comprise a range of over twenty colors; additional transitions between colors can always be introduced. Since our vision can easily distinguish between lightness and darkness in a color, and because pigments can be more easily mixed to obtain value changes then chroma changes, we will begin by manipulating the value of a hue.

Contrasting values in a design establish distinctive shapes. Gradual value changes, however, are used to express illusions of curved planes and edges of shapes that dissolve in rippling rhythms.

Value changes can be effected by mixing the color with white and/or black pigments in varying proportions. Value can either be manipulated to maintain maximum chroma or to suppress chroma to a minimum. The two methods might also be combined for a fuller monochromatic expression. [p. 35]

Manipulation of Value
In order to manipulate its value and maintain maximum chroma, a hue must be of considerable brilliance. White is added to obtain steps of lighter values, and black to obtain steps of darker values, but white and black are never added together. The addition of white creates clear tints, and black clear shades [no muddiness or grayness].

Using the gray scale as a guide, we can create nine value steps for a hue. The results resemble those forming the different steps at the right end of each horizontal row [in example] . . . .

The manipulation of value with minimum chroma makes the hue barely identifiable. To obtain the steps, white and black are mixed as different grays, and a small amount of the hue [about 10%] is added to each of them. The results resemble those steps forming the [example in a table corresponding to the gray scale]...[p. 36]

Value Gradations with Maximum Chroma
Colors seem to dissolve when they change gradually over a surface. The strongest color can extend into steps of lighter or darker colors; light steps can follow dark steps, or dark might follow light, to introduce contrast.

Numbers corresponding to the gray scale [in example] can be used to plan color distributions. If gradations are arranged as 1, 2, 3, 4, and 5, the value step proceed from dark to light. If after 8 comes a color corresponding to 2, there will be considerable value contrast. The strongest color may not always be at step 5, as a light hue would have more dark than light steps, and a dark hue more light than dark steps. Also bear in mind that the strongest color sometimes makes as great an impact as the lightest or darkest steps in a design. [p. 37]

Value Gradations with Minimum Chroma
Value gradations with minimum chroma can be used for a subtler effect. The gradual spreading of values creates a pearlike glow, and small areas of light tend to shine amid large dark areas.

Again, the number system can be used to plan color distributions. The steps might proceed smoothly from numbers 1 through 9 without the emergence of a color with full chroma. The lightest and darkest steps tend to be most prominent, and should therefore be positioned for impact. [p. 38]

CHROMA
Value is key to understanding chroma, as the value equivalent of a hue must be determined before chroma can be effectively manipulated.

First, we should have some notion of how a specific hue with the strongest possible chroma can be compared with a particular step of gray along the gray scale. This may not be accurate, as colors of the same hue that are manufactured differently might not be equal in value. The table below, which includes names of colors commonly used, can serve as a guide. Comparing the color in question with a step of gray suggested by the table, and with slightly lighter or darker steps, can help to locate the value equivalent of the color.

Another effective way to establish the value equivalent of a color is to place a sample of that color next to each step of the gray scale. Steps that are obviously too dark or too light can be quickly eliminated. The value equivalent of the color is the step that appears no lighter or darker than the sample.

9 Extremely light gray Lemon yellow
8 Light gray yellow
7 Very light gray Orange-yellow; golden yellow
6 Light middle gray Orange: Yellow-green; Magenta-red
5 Middle gray Red; Orange-red; Green; Cyan-blue
4 Dark middle gray Green-blue; Cobalt blue; Turquoise
3 Dark gray Purple: Ultramarine blue; Violet
2 Very dark gray Purple-blue; Prussian blue; Indigo
1 Extremely dark gray None
[P. 39]

The Manipulation of Chroma
Differences in value make it difficult to detect differences in chroma. If we concentrate on the manipulation of chroma, the value of a hue must be kept relatively constant. This can be done by limiting all changes in chroma to one value step.

The establishment of a value equivalent is affected by the source of illumination. Incandescent light makes blues darker and yellows lighter. Fluorescent light has an effect on color different from that of sunlight. I prefer initially to compare a color to the steps of the gray scale in broad daylight and to check it again in a dim corner, because we are better able to discriminate between values with a low level of light.

Once the equivalent value is determined, white and black pigments should be mixed to obtain the gray in that value step [pigments usually become lighter when they dry]. Gray should then be mixed with the color in the appropriate proportions.

The amount of gray mixed with a color and its possible effects are described in the table below; H stands for hue, N stands for gray. The six steps shown in the table can be increased; however, the number of steps in chroma gradations are usually far fewer than those in value gradations. Once the steps exceed six, the difference between one step and the next is often too close to be recognizable. Certain hues are more suited for a wider range of chroma manipulation than others.

Strong chroma H 100% N 0%
Considerable Chroma H 80% N 20%
Moderate Chroma H 50% N 40%
Weak Chroma H 40% N 60%
Faint Chroma H 20% N 80%
Absence of Chroma H 0% N 100%
[p. 40]

Chroma Gradations with No Shift in Value
[Example] shows chroma gradations of a hue with no change in its value. Ideally, all the steps should have the same level of gray in a black-and-white photograph taken of the [color] image.

When mixing a strong color and a gray of equal value, a small amount of the gray can quickly reduce the chroma of the color. This might also lower the value, in which case a small amount of white must be added to the mixture.

Chroma Gradations with Two Hues
It is possible to develop a design with a single hue of constant value and variations in chroma, but shapes may not emerge with sufficient clarity. In most cases, contrasting strong chroma and faint chroma, or absence of chroma, is more effective than creating fine gradations in chroma. A background of a darkened value or black is sometimes used to define shapes. If values, in addition to chroma, are varied, the result could be a full expression of the monochrome.

Until now I have discussed designs that are limited to one hue. Chroma variations or gradations are much more effective and interesting when two hues are used. The two hues do not have to be related in any particular way, but some contrast between them naturally exists. When the two colors are restricted to one value step, shapes can still be easily distinguished and an interesting color scheme results.

Two hues of the same value step are each mixed with a gray of equal value to obtain a full range of chroma gradations. If two hues have different values, these can be value adjusted by lightening the darker hue with white, or by darkening the lighter hue with black. [p. 41]

The hue that has not been mixed with gray has stronger chroma and will have more chroma gradations. The value-adjusted hue has weaker chroma and fewer chroma gradations.

It is also possible to adjust the value of both hues, mixing one with black and the other with white. The design that results will not feature strong chroma in any of its chroma gradations.... [pp. 41-42]

HUE
The term hue is often confused with color, but there is a distinction: variations of a single hue produce different colors. For instance, a red hue can be light red, dark red, dull or brilliant red, which are color variations within the same hue.

Nature does not provide us with the pigments to describe every hue in the spectrum; pigments that are now available are the products of human efforts throughout many centuries. We therefore have to choose pigments that closely match the standard hues.

It is common knowledge today that red, yellow, and blue can be intermixed to obtain almost any hue. Mixtures, however, weaken chroma, because of inaccurate hue expression, or the physical properties of the pigments, which come from plants, minerals, animal remains, or chemical compounds.

Regardless of these limitations, red, yellow, and blue are the three primary hues, and orange [a mixture of red and yellow], green [a mixture of yellow and blue], and purple [a mixture of blue and red] are the secondary hues. These constitute the six basic hues, which can be arranged in a circle. [p. 43]

Hue Gradations with Maintenance of Chroma
To effect gradations in hue, we should choose a hue [either one of the six basic hues or their intermediates] as a starting point and another as a terminating point on the color circle. In order to maintain strong chroma throughout the transitions, the two hues are not mixed directly, but each is mixed with an adjacent hue gradually approaching the other on the color circle.

It is simplest to begin with a primary and move to another primary hue. This can be done with the two primaries alone, or with all available pigments that represent the intermediate hues. For instance, we can proceed from cadmium red to cadmium orange with cadmium yellow deep and then cadmium yellow pale. If only red and yellow pigments are used, the mixtures will weaken chroma slightly.

It is more difficult to start with a secondary hue and arrive at another secondary hue. To proceed from purple to orange via red, for instance, it is necessary to use two red pigments: a cool red, such as magenta or rose, is mixed with purple; and a warmer red, such as flame red or vermilion, is mixed with orange. Mixing the cooler with the warmer reds produces an intermediate color. Similarly, when moving from orange to green via yellow, a cool yellow, such as lemon, and a warmer yellow, such as cadmium yellow pale, may be necessary. A cool blue, such as cerulean blue, and a warmer blue, such as ultramarine blue, should be considered when moving from green to purple via blue.

Many pigments are needed to effect hue gradations and maintain chroma [see Part III for a recommended list of pigments]. It is most important to acquire pigments with the strongest possible chroma, and if the pigment is a primary hue, it is necessary to determine which adjacent [secondary] hue the pigment most resembles. It is best to compare several pigments of the same hue and experiment with mixtures that produce different results. [p. 45]

Hue Gradations with Chroma Changes
Knowing the positions of hues on the color circle, and mixing these appropriately with all intermediate steps, results in hue gradations with full chroma. Chroma might also be intentionally weakened [to introduce contrast of chroma] by mixing any two secondary hues, or by mixing a primary hue with the secondary hue that is opposite it on the color circle--the two hues neutralize each other and become almost gray.

Another way to weaken chroma is to mix a primary hue with one adjacent [secondary] hue. For instance, a purple biased blue mixed with green produces a much duller blue-green than would result from mixing a green-biased blue with green. [p. 47]

The Color Solid
The three aspects of color--value, chroma, and hue--might be described as the dimensions of color and represented by a color solid. Different color systems use different solids to describe the relationships between colors; the color circle, used here, is most easily transformed into a sphere.

The sphere is composed of segments that represent specific hues in the spectrum. Six segments represent the six basic hues--red, orange, yellow, green, blue, and purple. If the sphere is horizontally divided, a color circle is revealed. The hue contained in each segment is represented in a variety of values. The upper part of the sphere is of higher value, approaching white at the top, and the lower part grows darker, becoming almost black at the bottom.

The inward-facing straight edge of the segment shows the hue in value gradations of minimum chroma. The outward-facing, curved side of the segment shows the hue in value gradations of maximum chroma. The strongest chroma occurs where bulging is most prominent. Amid the segments is a columnar section that represents the gray scale, with white gradually descending to black. [p. 47]

The sphere can be thought of as a globe. At the north pole is white and at the south pole black. Between the two poles, eight parallel latitude lines can be drawn, creating nine value zones, with the middle value zone covering the equator. Longitudinal lines divide the globe into six hue zones. Not all the hues in full chroma appear along the equator--the intrinsic value of a hue determines whether it appears in full chroma at the upper or lower portion of its zone. For instance, the strongest chroma of yellow, because it is of light value, occupies a position in the upper portion of the yellow zone. The strongest chroma of blue, because it is of relatively dark value, occupies a position in the so-called southern hemisphere. [An example] shows the two sides of this color globe; the location of the strongest chroma of each hue is indicated with black dots.

The sphere bulges wherever the strongest chroma occurs in each hue zone. The globe is therefore distorted in the appropriate places. [p. 48]

If the value zones in the globe are numbered, just as the steps of the gray scale were numbered, we can compare different hues of the same value.

[An example] shows how the six basic hues appear at the more common value zones and illustrate the way different hues can be value adjusted. In value zone 8, yellow is of strong chroma, but blue and purple are of faint chroma. At zone 7, orange-yellow is strong. At zone 6, orange and yellow-green are beginning to appear strong. At zone 5, red and green are at full chroma strength. At zone 4, blue-green, blue, and purple display considerable brilliance. [pp. 47-49]