Definiciones exclusivas para los Valores referenciados a Índices de Renta Variable

Ensembles of garments in monochromatic colors.

These constituents of light are known as the visible spectrum. Each color has a different wavelength. When light strikes a surface certain wavelengths are absorbed, and others are reflected by its pigments or coloring. Most light sources emit light at many different wavelengths, a process that gives a surface its color.

In 1860, Scottish physicist James Clerk Maxwell (1831– 1879) showed that light was a form of electromagnetic energy. The eye is able to receive light waves between 400 and 800 million cycles per second, and we perceive these cycles as color. Violet is the shortest and red the longest.

Hue

The first dimension of color is hue. A hue is the name or type of a color. When we refer to a color by its name we are referring to its hue. A pure hue is one which has no other color mixed in.

Certain hue combinations conform to standard categorizations.

Monochromatic: Of a single hue.

Analogous hues: Colors that are adjacent to each other in the spectrum.

Complementary hues: A pair of opposite colors as viewed on a color wheel. Mixing complementary colors lowers the saturation, or richness, and value, or luminosity, of the resulting color, in other words it has a darkening effect.

Triadic hues: Any three equidistant colors on the color spectrum when it is configured as a circle of hues. Red, yellow, and blue form the primary triad. When the full spectrum of color is presented as a wheel the relative positions of red, yellow, and blue conform to a perfect equilateral triangle.

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Color theory (above) The Itten color wheel organizes the basic theory of the interrelationship between the primary, secondary, and tertiary colors.

(left) The 12-color pigment wheel.

Color wheels

The color spectrum can be organized into wheels to help rationalize and predict color interactions. Color wheels are the first basic tools used in the analysis and discussion of color. There are many variations on the visual organization of color, some are simple in format and others highly complex, but their principles are all linked.

Pigment colors

In subtractive, or pigment, mixtures, the primaries are traditionally said to be red, yellow, and blue. If two primaries are mixed, they theoretically produce the secondaries orange, green, and purple. If all three are mixed, they theoretically produce black.

The pigment and process wheels

On the conventional 12-color wheel of pigment hues, the primaries are red, blue, and yellow; the secondaries are orange, green, and purple; and the tertiaries are mixtures of adjoining primaries and secondaries. If colors are mixed with their complement (the hue lying opposite on the wheel), a neutral gray should be created, as indicated in the center. The 12-step pigment wheel is the basis for working with subtractive color; textile artists will use a subtractive wheel to create colors of yarn and textiles by dyeing.

The 12-step process wheel also deals with subtractive color but the three basic primaries are purer—yellow, magenta, and cyan—that upon mixing also result in purer hues. This arrangement is the standard employed in color printing and photography, as well as pigment manufacture.

The Itten wheel

Devised by Swiss teacher and artist Johannes Itten (1888–1967), the Itten wheel shows a logical and easily remembered format for working with color pigments. Itten was captivated by color, from both a scientific and a spiritual point of view, and taught at the influential Bauhaus School in Germany in the 1920s. He observed that colors can be classified as warm or cool shades, and looked at how the two combined can affect each other. Theoretical elements, including the Itten color wheel, generated from the Bauhaus teachings still inform art instruction around the world today.

The Itten color wheel organizes the basic theory of the interrelationship between the primary, secondary, and tertiary colors in a practical graphic format. The triangle in the center shows the three primary colors, yellow, blue, and red, which cannot be created by mixing any of the other pigments. Surrounding them are the three secondary colors, which are produced by mixing the primaries. The wheel that encircles the primaries and secondaries is divided into 12 sectors. Six of these are primaries and secondaries, and between each of these is another color. Itten referred to these as tertiary colors. A tertiary color is the result of mixing a primary and a secondary color.

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Introducing color

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Light colors

These colors are additive rather than subtractive (like pigments). If primary-colored lights—red-orange, green, and blue-violet— are projected in overlapping circles, they mix to form the light secondaries yellow, magenta, and cyan. In additive mixtures, the secondaries are paler than the primaries. Where all three primaries overlap, they produce white. This system is used for lighting and also forms the basis for video and computer graphics.

Light colors are additive (above), and react differently to pigment colors, which are subtractive (below).

The Munsell wheel

Albert Munsell (1858–1918) developed a partitive color system (below) based on five primary hues, or as he referred to them, principal colors of yellow, red, green, blue, and purple. These primaries are based on after-image perceptions—when the brain supplies the opposite color after staring at a particular hue—that derive from hues we see in nature.

The visual wheel

The 16-step visual wheel (below) was arranged by the Italian artist Leonardo da Vinci (1452–1519), whose understanding of complementary colors greatly influenced Renaissance painting. It is a partitive and subtractive color wheel.

yellow _orangeyellow- orange re d- orange re d re d-violet- re d red-_violet violet-r ed- violet violet violet-blue-_violet blue- violet blue-violet- blue blue blue-gr een- blue blue- gr een gr een -bl ue- gr een green green-y ello w- green yellow- green

yello_yellow-green-w

The Munsell wheel

yellow-gr een- yellow yellow yellow- orange orange re d- orange re d red-_violet violet blue- violet blue blue-gr een- blue blue- gr_een gr een-blue- gr een gr een green-y ello w- green yello w- green F4F_02_colour_2e_US.indd 48 F4F_02_colour_2e_US.indd 48 29/08/2013 07:5129/08/2013 07:51

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