# Base color

Color wheel according to Johannes Itten (1961)
Color valence = the color of how the light-emitting diodes are perceived
Color stimulus = spectrum of light-emitting diodes in red, green, blue and white

In the narrower sense, basic colors are the color valences theoretically used as a reference value in a selected color space . In a broader sense, it is the for mixing usable colorants to a certain color perception to achieve.

## Terms

### General

A “ three-color theory ” is based on the experience of the artists with the basic colors red, yellow and blue, from which all other colors can be mixed. For the RGB color space, on the other hand, it is the three valences red, green and blue to which the luminescent substances of the monitor are optimally matched. The basic colors of a multicolor print, for example an inkjet print, are: yellow, magenta (red-blue / fuchsia) and cyan (blue-green). Three basic colors are sufficient to describe the color space , but perception is based on pairs of opposites ( four-color theory ). In principle, different color triples are possible as basic colors for the description of the colors .

### Spectral color

Spectral colors are the bright, pure colors as they appear in the solar spectrum, on the edge of CDs or in the rainbow. Because of the sacred number seven, Newton assigned seven basic colors to this continuum: violet , indigo , blue , green , yellow , yellow- red , red , although the continuum offers a continuous color sequence. The "white" light is broken down into the "bright" colors of the spectrum by means of diffraction or interference effects. More precisely, it is color stimuli that are perceived as color valences due to the wavelength-dependent splitting. A spectral color is typically the appearance of a “single” wavelength or (real) monochromatic light. "Mixtures" of several spectral colors are called valence colors , so the valence color magenta is an "overlay" of the spectral colors violet and red.

### Color valence

The triggering event of the color impression is the color stimulus , the calculated quantity (numerical value or vector ) resulting from this is the color valence .

### Primary valences

When developing the CIE standard valence system , three primary valences were determined as calibration color values, which are derived from the sensitivities of the three cones . The primary valences correspond to the LMS color space , the L cone (valence)    is denoted by, the primary valence is   assigned to the M cone and the primary valence derived from the sensitivity spectrum of the S cone is    denoted by. These primary valences are used as basis vectors of a three-dimensional color space. The letters L , M and S for the cones stand for long, medium and shortwave. ${\ displaystyle {\ vec {R}}}$${\ displaystyle {\ vec {G}}}$${\ displaystyle {\ vec {B}}}$

At the beginning of color measurement, these primary valences were measured indirectly. With this measuring technique, light was subtracted (by changing the comparison light), so to speak, color was removed. In order to avoid such negative color values, virtual basic valences were derived according to the calculation rules for vectors , which span the color space, these are

${\ displaystyle {\ vec {X}}}$   as red,   green and   blue valence.${\ displaystyle {\ vec {Y}}}$${\ displaystyle {\ vec {Z}}}$

### Non-color

The parameters required for the 3D model display are selected in various color spaces in such a way that the color valence obtained does not correspond to any visible color or that the result is outside the gamut . In colorimetry, such (imperceptible) color locations are referred to as “non-color” or, better, as imaginary colors .

### Base color

Although the visible spectrum and the variety of all color nuances practically form a continuum, a restriction to a few color names is necessary for communication. Depending on the language and culture, there are two to six names for colors that are considered basic colors.

The term basic color was developed in American linguistics in the 1960s in a (still controversial) language universalist hypothesis. In the influential Basic Color Terms (1969), Brent Berlin and Paul Kay suggested that all languages ​​have a minimum occupation of two color categories in their vocabulary (such as white / light and black / dark); in addition, the third category is red, the fourth yellow or green, etc., up to a maximum of 11 categories. The Berlin / Kaysche model was later applied with considerable modifications by German linguists, who mostly recognize 8 to 11 basic color words (see color ).

In his theoretical writings, Goethe used the word basic color (mostly as plural) in the sense of "primary color valences" (in painting, dyeing, chemistry and optics) ", for example blue, yellow and red. The Goethe dictionary also documents Goethe's varied use of elementary color , main color and primary color , often with reference to his different color schemes. About Goethe's understanding of color and the development of his color theories. (See color theory and color theory (Goethe) )

In the experience of the painters and subsequently theoretically with the French Jacques-Christophe Le Blond and in Young's three-color theory , these are: red, yellow, blue. They are "basic" colors from which all others can be mixed. According to Ewald Hering's counter-color theory, there are four basic colors , these form the pairs green-red and blue-yellow (in addition to light-dark). Ostwald , Itten and Küppers founded their color theories from the possibility of basically finding other basic color triples.

For the RGB color space it is the three valences red, green and blue to which the luminescent substances of the monitor can be optimally matched. As an alternative, in newer devices a yellow is also selected under conversion in order to better simulate the LMS color space of the eye.

### Primary colors and secondary colors

(Subtractive) primary colors in color printing

Historically, a subdivision into primary and secondary colors has emerged, the former being fundamental and the secondary colors being mixed directly from them.

Primary colors are the initial colors of an imaginary or actual mixing process. For the additive mixture are light colors used (usually red, green and blue), for the subtractive mixing of the body colors cyan, yellow and magenta, often with the aid of an additional black pigment, such as a process color in color printing .

Secondary colors are mixtures of two primary colors.

Rudolf Arnheim recommends distinguishing between “generative” and “fundamental” primary colors. Generative primary colors are colors that are used for mixing, i.e. for generating secondary colors. Fundamental primary colors, on the other hand, are the primary colors of the psychological level. It turns out that test subjects can describe any color well by describing the colors as mixtures of the four colors red, yellow, green and blue (this is what the NCS is based on ). On the other hand, it is psychologically hardly possible to imagine yellow as a mixture of red and green (i.e. in an additive mixture). A “bluish yellow” can hardly be imagined as a yellow-green (as a subtractive mixture).

According to this structure, the term tertiary color should be understood to mean those that can be explained by further mixing; in this sense it is the broken colors ( clouded colors ). Typical representatives are the range of brown tones , which can be a broken yellow, red or orange. Tertiary colors from cold shades lead to the group of olive tones. In the real sense, the achromatic colors white, gray and black also belong to the tertiary colors. From Ostwald , the term "veiled colors" was coined in his color theory, since them the clarity of saturated colors is missing.

### Optimal colors

Spectrum of an optimal color over a spectral-like color design

Enhanced by Wilhelm Ostwald and Robert Luther , the term "optimal colors" arose for idealized colors that are based on sections of the spectrum, whereby the intensities only assume the values ​​0 and 1. Depending on the location of the jump wavelengths, there are blue short-end colors, green middle colors, red long-end colors and purple middle-wrong colors.

### Chiaroscuro, achromatic colors

Somewhat apart from the bright colors, there are black and white , the “extreme” cases of neutral gray . These achromatic colors play a separate role because they are (precisely) not colored.

Wilhelm Ostwald uses the terms veiled (that is blackened) and whitish colors, which he opposed to the optimal colors. Siegfried Rösch achieved the breakthrough for this by deriving the concept of relative brightness from the optimal colors .

### Full color

In Ostwald's color wheel, full color is the name for the color. They are the most saturated and purest (because narrowly limited) optimal colors . In this color system, the colors are more cloudy and less saturated by black, and are called blackened light. The addition of white, the whitening, causes an increase in the brightness of the color. If the white component of the full color component is displaced, the achromatic color white is obtained. The total part sum " color = full color part v + white part w + black part s " is always 100%, because more than color is not possible.

### Primordial colors

Ewald Hering based his counter-color theory on the four primary colors red, yellow, blue and green , whereby the color pairs red / green and blue / yellow exclude each other as opposing colors.

For his color theory, Küppers uses the term primordial colors for the color sensations orange-red (R), green (G) and violet-blue (B). These primordial colors result from the (symbolized) "sensory forces" of the visual organ, as they ultimately form the basis of the LMS color space .

## Basic colors in languages

The color wheel , which is perceived as continuous, can be divided differently by basic colors. What is referred to or perceived as the basic color depends on cultural traditions and conventions.

In the European system (Indo-European language area) four (or six) colors are used as a basis: In addition to "black" and "white", the four basic "bright" colors "red", "blue", "yellow" and "green" are known . However, this naming system is relatively new. In ancient times , completely different basic colors were used.

Germanic color names penetrated the Romance languages after the Migration Period : The Germanic color word gel (yellow, English yellow ) can be found as giallo in Italian and similarly in other Romance languages. The Old High German blao (blue) was also adopted from several Romance languages: French bleu , Italian blu and Catalan blue .

The word blanc ( Catalan and French for “white”, also Italian bianco , Spanish blanco and Portuguese branco ) also has a Germanic origin that is still recognizable in the German word “blank”. The actual Latin word for “white”, however, was albus (compare album), which lives on in Portuguese alvo (“white”, “pure”), in Romanian alb (“white”) and in Spanish alba (“dawn”). Compare with blanco and oscuro (for light and dark).

The color word “azur” (cf. “ Côte d'Azur ”) known from older (southern) French varieties can also be found in Italian azzurro and Spanish: azul . Originally Italian speakers perceive blu (dark blue) and azzurro (sky blue) as completely different basic colors, such as how yellow and green represent different colors for a German speaker . For the Romans, the sky was not “blue” but “bright”.

In Greek , χλωρός (chloros) stands for “yellow-green” (compare the element chlorine and chlorophyll ), γλαυκός (glaucos) is a dull “blue-gray-green” (compare glaucoma ).

The Japanese language has other than the borrowing of "gurin" (green) from English No Category Green , but "green" is (yellow) as a shade of blue viewed ( development language ).

The Chinese language differentiates between two types of green: 綠色 (lü se) or just 綠 (lü) for a light, more yellowish green and 青色 (qing se) for a rich, bluish green, turquoise or cyan.