Read Ebook: A Color Notation A measured color system based on the three qualities Hue Value and Chroma by Munsell A H Albert Henry

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A COLOR SYSTEM AND COURSE OF STUDY BASED ON THE COLOR SOLID AND ITS CHARTS. Arranged for nine years of school life.

INDEX .

COLOR NAMES.

Writing from Samoa to Sidney Colvin in London, Stevenson says: "Perhaps in the same way it might amuse you to send us any pattern of wall paper that might strike you as cheap, pretty, and suitable for a room in a hot and extremely bright climate. It should be borne in mind that our climate can be extremely dark, too. Our sitting-room is to be in varnished wood. The room I have particularly in mind is a sort of bed and sitting room, pretty large, lit on three sides, and the colour in favour of its proprietor at present is a topazy yellow. But then with what colour to relieve it? For a little work-room of my own at the back I should rather like to see some patterns of unglossy--well, I'll be hanged if I can describe this red. It's not Turkish, and it's not Roman, and it's not Indian; but it seems to partake of the last two, and yet it can't be either of them, because it ought to be able to go with vermilion. Ah, what a tangled web we weave! Anyway, with what brains you have left choose me and send me some--many--patterns of the exact shade."

Where could be found a more delightful cry for some rational way to describe color? He wants "a topazy yellow" and a red that is not Turkish nor Roman nor Indian, but that "seems to partake of the last two, and yet it can't be either of them." As a cap to the climax comes his demand for "patterns of the exact shade." Thus one of the clearest and most forceful writers of English finds himself unable to describe the color he wants. And why? Simply because popular language does not clearly state a single one of the three qualities united in every color, and which must be known before one may even hope to convey his color conceptions to another.

The incongruous and bizarre nature of our present color names must appear to any thoughtful person. Baby blue, peacock blue, Nile green, apple green, lemon yellow, straw yellow, rose pink, heliotrope, royal purple, Magenta, Solferino, plum, and automobile are popular terms, conveying different ideas to different persons and utterly failing to define colors. The terms used for a single hue, such as pea green, sea green, olive green, grass green, sage green, evergreen, invisible green, are not to be trusted in ordering a piece of cloth. They invite mistakes and disappointment. Not only are they inaccurate: they are inappropriate. Can we imagine musical tones called lark, canary, cockatoo, crow, cat, dog, or mouse, because they bear some distant resemblance to the cries of those animals? See paragraph 131.

+Color needs a system.+

Music is equipped with a system by which it defines each sound in terms of its pitch, intensify, and duration, without dragging in loose allusions to the endlessly varying sounds of nature. So should color be supplied with an appropriate system, based on the hue, value, and chroma of our sensations, and not attempting to describe them by the indefinite and varying colors of natural objects. The system now to be considered portrays the three dimensions of color, and measures each by an appropriate scale. It does not rest upon the whim of an individual, but upon physical measurements made possible by special color apparatus. The results may be tested by any one who comes to the problem with "a clear mind, a good eye, and a fair supply of patience."

+Clear mental images make clear speech. Vague thoughts find vague utterance.+

The child gathers flowers, hoards colored beads, chases butterflies, and begs for the gaudiest painted toys. At first his strong color sensations are sufficiently described by the simple terms of red, yellow, green, blue, and purple. But he soon sees that some are light, while others are dark, and later comes to perceive that each hue has many grayer degrees. Now, if he wants to describe a particular red,--such as that of his faded cap,--he is not content to merely call it red, since he is aware of other red objects which are very unlike it. So he gropes for means to define this particular red; and, having no standard of comparison,--no scale by which to estimate,--he hesitatingly says it is a "sort of dull red."

Thus early is he cramped by the poverty of color language. He has never been given an appropriate word for this color quality, and has to borrow one signifying the opposite of sharp, which belongs to edge tools rather than to colors.

+Most color terms are borrowed from other senses.+

When his older sister refers to the "tone" of her green dress, or speaks of the "key of color" in a picture, he is naturally confused, because tone and key are terms associated in his mind with music. It may not be long before he will hear that "a color note has been pitched too high," or that a certain artist "paints in a minor key." All these terms lead to mixed and indefinite ideas, and leave him unequipped for the clear expression of color qualities.

Musical art is not so handicapped. It has an established scale with measured intervals and definite terms. Likewise, coloristic art must establish a scale, measure its intervals, and name its qualities in unmistakable fashion.

+Color has three dimensions.+

It may sound strange to say that color has three dimensions, but it is easily proved by the fact that each of them can be measured. Thus in the case of the boy's faded cap its redness or HUE is determined by one instrument; the amount of light in the red, which is its VALUE, is found by another instrument; while still a third instrument determines the purity or CHROMA of the red.

The omission of any one of these three qualities leaves us in doubt as to the character of a color, just as truly as the character of this studio would remain undefined if the length were omitted and we described it as 22 feet wide by 14 feet high. The imagination would be free to ascribe any length it chose, from 25 to 100 feet. This length might be differently conceived by every individual who tried to supply the missing factor.

The fruit is then filled with assorted colors, graded from white to black, according to their VALUES, and disposed by their HUES in the five sections. A slice near the top will uncover light values in all hues, and a slice near the bottom will find dark values in the same hues. A slice across the middle discloses a circuit of hues all of MIDDLE VALUE; that is, midway between the extremes of white and black.

Two color dimensions are thus shown in the orange, and it remains to exhibit the third, which is called CHROMA, or strength of color. To do this, we have only to take each section in turn, and, without disturbing the values already assorted, shove the grayest in toward the narrow edge, and grade outward to the purest on the surface. Each slice across the fruit still shows the circuit of hues in one uniform value; but the strong chromas are at the outside, while grayer and grayer chromas make a gradation inward to neutral gray at the centre, where all trace of color disappears. The thin edges of all sections unite in a scale of gray from black to white, no matter what hue each contains.

The curved outside of each section shows its particular hue graded from black to white; and, should the section be cut at right angles to the thin edge, it would show the third dimension,--chroma,--for the color is graded evenly from the surface to neutral gray. A pin stuck in at any point traces the third dimension.

+A color sphere can be used to unite the three dimensions of hue, value, and chroma.+

Having used the familiar structure of the orange as a help in classifying colors, let us substitute a geometric solid, like a sphere, and make use of geographical terms. The north pole is white. The south pole is black. The equator is a circuit of middle reds, yellows, greens, blues, and purples. Parallels above the equator describe this circuit in lighter values, and parallels below trace it in darker values. The vertical axis joining black and white is a neutral scale of gray values, while perpendiculars to it are scales of chroma. Thus our color notions may be brought into an orderly relation by the color sphere. Any color describes its light and strength by its location in the solid or on the surface, and is named by its place in the combined scales of hue, value, and chroma.

+Two dimensions fail to describe a color.+

Much of the popular misunderstanding of color is caused by ignorance of these three dimensions or by an attempt to make two dimensions do the work of three.

Flat diagrams showing hues and values, but omitting to define chromas, are as incomplete as would be a map of Switzerland with the mountains left out, or a harbor chart without indications of the depth of water. We find by aid of the measuring instruments that pigments are very unequal in this third dimension,--chroma,--producing mountains and valleys on the color sphere, so that, when the color system is worked out in pigments and charted, some colors must be traced well out beyond the spherical surface . Indeed, a COLOR TREE is needed to display by the unequal levels and lengths of its branches the individuality of pigment colors. But, whatever solid or figure is used to illustrate color relations, it must combine the three scales of hue, value, and chroma, and these definite scales furnish a name for every color based upon its intrinsic qualities, and free from terms purloined in other sensations, or caught from the fluctuating colors of natural objects.

+How this system describes the spectrum.+

The solar spectrum and rainbow are the most stimulating color experiences with which we are acquainted. Can they be described by this solid system?

The lightest part of the spectrum is a narrow field of greenish yellow, grading into darker red on one side and into darker green upon the other, followed by still darker blue and purple. Upon the sphere the values of these spectral colors trace a path high up on the yellow section, near white, and slanting downward across the red and green sections, which are traversed near the level of the equator, it goes on to cross the blue and purple well down toward black.

This forms an inclined circuit, crossing the equator at opposite points, and suggests the ecliptic or the rings of Saturn . A pale rainbow would describe a slanting circuit nearer white, and a dimmer one would fall within the sphere, while an intensely brilliant spectrum projects far beyond the surface of the sphere, so greatly is the chroma of its hues in excess of the common pigments with which we work out our problems.

At the outset it is well to recognize the place of the spectrum in this system, not only because it is the established basis of scientific study, but especially because the invariable order assumed by its hues is the only stable hint which Nature affords us in her infinite color play.

All our color sensations are included in the color solid. None are left out by its scales of hue, value, and chroma. Indeed, the imagination is led to conceive and locate still purer colors than any we now possess. Such increased degrees of color sensation can be named, and clearly conveyed by symbols to another person as soon as the system is comprehended.

+Misnomers for Color.+

Obscure statements were frequent in text-books before these new definitions appeared. Thus the term "shade" should be applied only to darkened values, and not to hues or chromas. Yet one writer says, "This yellow shades into green," which is certainly a change of hue, and then speaks of "a brighter shade" in spite of his evident intention to suggest a stronger chroma, which is neither a shade nor brighter luminosity.

"Intensity" is a misleading term, if chroma be intended, for it depends on the relative light of spectral hues. It is a degree rather than a quality, as appears in the expressions, intense heat, light, sound,--intensity of stimulus and reaction. Being a degree of many qualities, it should not be used to describe the quality itself. The word becomes especially unfit when used to describe two very different phases of a color,--as its intense illumination, where the chroma is greatly weakened, and the strongest chroma which is found in a much lower value. "Purity" is also to be avoided in speaking of pigments, for not one of our pigments represents a single pure ray of the spectrum.

Examples are constantly found of the mental blur caused by such unfortunate terms, and, since misunderstanding becomes impossible with measured degrees of hue, value, and chroma, it seems only a question of time when they will take the place of tint, tone, shade, purity and intensity.

COLOR QUALITIES.

The three color qualities are hue, value, and chroma.

+HUE is the name of a color.+

Hue is the quality by which we distinguish one color from another, as a red from a yellow, a green, a blue, or a purple. This names the hue, but does not tell whether it is light or dark, weak or strong,--leaving us in doubt as to its value and its chroma.

Science attributes this quality to difference in the LENGTH of ether waves impinging on the retina, which causes the sensation of color. The wave length M. 5269 gives a sensation of green, while M. 6867 gives a sensation of red.

+VALUE is the light of a color.+

Value is the quality by which we distinguish a light color from a dark one. Color values are loosely called tints and shades, but the terms are frequently misapplied. A tint should be a light value, and a shade should be darker; but the word "shade" has become a general term for any sort of color, so that a shade of yellow may prove to be lighter than a tint of blue. A photometric scale of value places all colors in relation to the extremes of white and black, but cannot describe their hue or their chroma.

Science describes this quality as due to difference in the HEIGHT or amplitude of ether waves impinging on the retina. Small amplitudes of the wave lengths given in paragraph 21 produce the sensation of dark green and dark red: larger amplitudes give the sensation of lighter green and lighter red.

+CHROMA is the strength of a color.+

Chroma is the quality by which we distinguish a strong color from a weak one. To say that a rug is strong in color gives no hint of its hues or values, only its chromas. Loss of chroma is loosely called fading, but this word is frequently used to include changes of value and hue. Take two autumn leaves, identical in color, and expose one to the weather, while the other is waxed and pressed in a book. Soon the exposed leaf fades into a neutral gray, while the protected one preserves its strong chroma almost intact. If, in fading, the leaf does not change its hue or its value, there is only a loss of chroma, but the fading process is more likely to induce some change of the other two qualities. Fading, however, cannot define these changes.

Science describes chroma as the purity of one wave length separated from all others. Other wave lengths, INTERMINGLING, make its chroma less pure. A beam of daylight can combine all wave lengths in such balance as to give the sensation of whiteness, because no single wave is in excess.

The color sphere is a convenient model to illustrate these three qualities,--hue, value, and chroma,--and unite them by measured scales.

+HUES first appeal to the child, VALUES next, and CHROMAS last.+

Color education begins with ability to recognize and name certain hues, such as red, yellow, green, blue, and purple . Nature presents these hues in union with such varieties of value and chroma that, unless there be some standard of comparison, it is impossible for one person to describe them intelligently to another.

The solar spectrum forms a basis for scientific color analysis, taught in technical schools; but it is quite beyond the comprehension of a child. He needs something more tangible and constantly in view to train his color notions. He needs to handle colors, place them side by side for comparison, imitate them with crayons, paints, and colored stuffs, so as to test the growth of perception, and learn by simple yet accurate terms to describe each by its hue, its value, and its chroma.

Pigments, rather than the solar spectrum, are the practical agents of color work. Certain of them, selected and measured by this system , will be known as MIDDLE COLORS, because they stand midway in the scales of value and chroma. These middle colors are preserved in imperishable enamels, so that the child may handle and fix them in his memory, and thus gain a permanent basis for comparing all degrees of color. He learns to grade each middle color to its extremes of value and chroma.

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