# A Color Notation/Glossary

GLOSSARY OF COLOR TERMS
TAKEN FROM THE
CENTURY DICTIONARY.
The color definitions here employed are taken from the Century Dictionary. Special attention 1s called to the cross references which serve to differentiate HUE, VALUE, and CHROMA.
After Imaage.—An image perceived after withdrawing the eye from a brilliantly illuminated object. Such images are called positive when their colors are the same as that of the object, and negative when they are its complementary colors.
Blue.—Of the color of the clear sky; of the color of the spectrum between wave lengths .505 and .415 micron, and more especially .487 and .460; or of such light mixed with white; azure, cerulean.
Black.—Possessing in the highest degree the property of absorbing light; reflecting and transmitting little or no light; of the color of soot or coal; of the darkest possible hue; sable. Optically, wholly destitute of color, or absolutely dark, whether from the absence or the total absorption of light. Opposed to white.
Brown.—A dark color, inclined to red or yellow, obtained by mixing red, black, and yellow.
CHROMA.—The degree of departure of a color sensation from that of white or gray; the intensity of distinctive hue; color intensity.
Curomatic.—Relating to or of the nature of color.
Cobalt Blue.—A pure blue tending toward cyan blue and of high luminosity; also called Hungary blue, Lethner’s blue, and Paris blue.
​Color.—Objectively, that quality of a thing or appearance which is perceived by the eye alone, independently of the form of the thing; subjectively, a sensation peculiar to the organ of vision, and arising from the optic nerve.
Color Blindness.—Incapacity for perceiving colors, independent of the capacity for distinguishing light and shade. The most common form is inability to perceive red as a distinct color, red objects being confounded with gray or green; and next in frequency is the inability to perceive green.
Color Constants.—The numbers which measure the quantities, as well as any other system of three numbers for defining colors, are called constants of color.
Color Variables.—Colors vary in CHROMA, or freedom from ad-mixture of white light; in BRIGHTNESS, or luminosity; and in HUE, which roughly corresponds to the mean wave length of the light emitted.
Colors, Complemntary.—Those pairs of color which when mixed produce white or gray light, such as red and green-blue, yellow and indigo-blue, green-yellow and violet.
Colors, Primary.—The red, green, and violet light of the spectrum, from the mixture of which all other colors can be produced. Also called fundamental colors.
Dyestuffs.—In commerce, any dyewood, lichen, or dyecake used in dyeing and staining.
Electric Light.—Light produced by electricity and of two general kinds, the arc. light and the incandescent light. In the first the voltaic arc is employed. In the second a resisting conductor is rendered incandescent by the current.
Enamel.—In the fine arts a vitreous substance or glass, opaque or transparent, and variously colored, applied as a coating on a surface of metal or of porcelain.
​Grating, Diffraction.—A series of fine parallel lines on a surface of glass, or polished metal, ruled very close together, at the rate of 10,000 to 20,000 or even 40,000 to the inch; distinctively called a diffraction or a diffraction grating, much used in spectroscopic work.
Gray.—A color having little or no distinctive hue (chroma) and only moderate luminosity.
Green.—The color of ordinary foliage; the color seen in the solar spectrum between wave lengths 0.511 and 0.543 micron.
Emerald Green.—A highly chromatic and extraordinarily luminous green of the color of the spectrum at wave length 0.524 micron. It recalls the emerald by its brilliancy, but not by its tint; applied generally to the aceto-arsenate of copper. Usually known as Paris green.
High Color.—A hue which excites intensely chromatic color sensations.
HUE.— Specifically and technically, distinctive quality of coloring in an object or on a surface; the respect in which red, yellow, green, blue, etc., differ one from another; that in which colors of equal luminosity and CHROMA may differ.
Indigo.—The violet-blue color of the spectrum, extending, according to Helmholtz, from G two-thirds of the way to F in the prismatic spectrum. ‘The name was introduced by Newton, but has lately been discarded by the best writers.
Light.—Adjective applied to colors highly luminous and more or less deficient in chroma.
Luminosity.—Specifically, the intensity of light in a color, measured photometrically; that is to say, a standard light has its intensity, or vis viva, altered, until it produces the impression of being equally bright with the color whose light is to be ​determined; and the measure of the vis viva of the altered light, relatively to its standard intensity, is then taken as the luminosity of the color in question.
Maxwell Color Discs.—Discs having each a single color, and slit radially so that one may be made to lap over another to any desired extent. By rotating these on a spindle, the effect of combining certain colors in varying proportions can be studied.
Micron.—The millionth part of a metre, or 1/23400 of an English inch. The term has been formally adopted by the International Commission of Weights and Measures, representing the civilized nations of the world, and is adopted by all metrologists.
Orange.—A reddish yellow color, of which the orange is the type.
Vision, Persistence of.—The continuance of a visual impression upon the retina of the eye after the exciting cause is removed. The length of time varies with the intensity of the light and the excitability of the retina, and ordinarily is brief, though the duration may be for hours, or even days. The after image may be either positive or negative, the latter when the bright part appears dark and the colored parts in their corresponding contrast colors. It is because of this persistence that, for example, a firebrand moved very rapidly appears as a band or circle of light.
Photometer.—An instrument used to measure the intensity of light. Specifically, to compare the relative intensities of the light emitted from various sources.
Pigment.—Any substance that is or can be used by painters to impart color to bodies.
Pink.—A red color of low chroma, but high luminosity, inclining toward purple.
​Primary Colors.—See Colors, primary.
Pure Color.—A color produced by homogeneous light. Any very brilliant or decided color.
Purple.—A color formed by the mixture of blue and red, including the violet of the spectrum above wave length 0.417, which is nearly a violet blue, and extending to, but not including, crimson.
Rainbow.—A bow or an arc of a circle, consisting of the prismatic colors, formed by the refraction and the reflection of rays of light from drops of rain or vapor, appearing in the part of-the heavens opposite to the sun.
Red.—A color more or less resembling that of blood, or the lower end of the spectrum. Red is one of the most general color names, and embraces colors ranging in hue from aniline to scarlet iodide of mercury and red lead. A red yellower than vermilion is called scarlet. One much more crimson is called crimson red. A very dark red, if pure or crimson, is called maroon; if brownish, chestnut or chocolate. A pale red—that is, one of low chroma and high luminosity—is called a pink, ranging from rose pink or pale crimson to salmon pink or pale scarlet.
Venetian Red.—An important pigment used by artists, somewhat darker than brick red in color, and very permanent.
Retina.—The innermost and chiefly nervous coat of the posterior part of the eyeball.
Saturation, of colors.—In optics the degree of admixture with white, the saturation diminishing as the amount of white is increased. In other words, the highest degree of saturation belongs to a given color when in the state of greatest purity.
​Scale.—A graded system, by reference to which the degree, intensity, or quality of a sense perception may be estimated.
Shade.—Degree or gradation of defective luminosity in a color, often used vaguely from the fact that paleness, or high luminosity, combined with defective chroma, is confounded with high luminosity by itself. See Color, Hue, and Tint.
Spectrum.—In physics the continuous band of light showing the successive prismatic colors, or the isolated lines or bands of color, observed when the radiation from such a source as the sun or an ignited vapor in a gas flame is viewed after having been passed through a prism (prismatic spectrum) or reflected from a diffraction grating (diffraction or interference spectrum). See Rainbow.
Tint.—A variety of color; especially and properly, a luminous variety of low chroma; also, abstractly, the respect in which a color may be raised by more or less admixture of white, which at once increases the luminosity and diminishes the chroma.
Tone.—A sound having definiteness and continuity enough so that its pitch, force, and quality may be readily estimated by the ear. Musical sound opposed to noise. The prevailing effect of a color.
Ultramarine.—A beautiful natural blue pigment, obtained from the mineral lapis-lazuli.
VALUE.—In painting and the allied arts, relation of one object, part, or atmospheric plane of a picture to the others, with reference to light and shade, the idea of HUE being abstracted.
Vermillion.—The red sulphate of mercury.
Violet.—A general class of colors, of which the violet flower is a ​highly chromatic example. The sensation is produced by a pure blue whose chroma has been diminished while its luminosity has been increased. Thus blue and violet are the same color, though the sensations are different. A mere increase of illumination may cause a violet blue to appear violet, with a diminution of apparent chroma. This color, called violet or blue according to the quality of the sensation it excites, is one of the three fundamental colors of Young’s theory. A deep blue tinged with red.
Virdian.—Same as Veronese green.
White.—A color transmitting, and so reflecting to the eye, all the rays of the spectrum, combined in the same proportion as in the impinging light.
Yellow—The color of gold and of light, of wave length 0.581 micron. ‘The name is restricted to highly chromatic and luminous colors. When reduced in chroma, it becomes buff; when reduced in luminosity, a cool brown. See Brown.
Veronese Green.—A pigment consisting of hydrated chromium sesquioxide. It is a clear bluish green of great permanency. Also called Viridian.