Color

Color is an individual visual perception, which is caused by light. The perceptible to the human color stimuli are in the range between 380 nm and 780 nm of the electromagnetic spectrum. The color perception is subjective distinguished by the nature of the eyes, sensitivity of the receptors and the following perceptual apparatus. Other optical perceptions like structure ( light-shadow effects ), gloss or roughness, as well as psychological effects and phenomena of the visual system, such as re-tuning or adaptation must be distinguished from the concept of color.

"Color is the one visual sensation of the eye of the metallic shine part of the visual field by which this part of Color derives from one-eyed observation with an impassive eye of a the same time, also structureless adjacent district may differ alone. " ( Definition according to DIN 5033 )

• 7.1 Cold or warm
• 7.2 color groups

Sense of the word color

Color has several meanings of words.

In other languages ​​stronger between the effect color ( " color " ) and is the cause of color ( " color" ) distinguished, as in English, color and dye ( stuff ), or in the Romance languages ​​(Spanish: color and teñir ).

"Colors are a complex matter that interest them both physiologists and psychologists as the artist and esthetician, they play a role in radiotherapy, but they do not form less a physical issue. However, we need to delineate this correctly, us three times the conscious use of language. [ ... ] If we ignore the spectral colors, but can the same color (now always meant in the sense of feeling ) are produced by an infinite number of combinations of light rays. A color is indeed uniquely determined by its " physical composition ", but not characterized. And yet it has, regardless of the nature of her arousal, a " self- existence ". "

In this article, not the origination of colors is explained and the supplementary terms for color treated under color.

Perception

Color is perceived, it is produced by the visual appeal in the color receptors in response to a color stimulus is like the mechanical stimulus caused by pressure or roughness. Color is not the property of seen the light ( color stimulus ), it is the subjective perception of the physical cause of electromagnetic waves between 380 nm and 780 nm According to the spectral color stimulus (different intensities of light ) different color stimuli caused, the different qualities of color perception forming, as a result, different colors to be perceived.

The optical phenomenon of color perception is a research field of comprehensive complexity. There are intertwined physical ( spectrum), physiological perception ( color stimulus ) and perceptual psychology ( color valency ) and linguistically -conventional aspects. The visual perception of humans by receptors that are located on the retina: rods for Hell-/Dunkel-Kontrast, the cones for color perception (not suppository ).

Journals are available in three versions, each of which have their maximum sensitivity in the spectral " red", " green " and "blue". Color can be represented on the basis of three types of color receptors in humans as three-dimensional property. Any combination of the three types of cones with suggestions (light) radiation that impinges on the retina, causes a specific color impression. Thus, Schwarz ( no excitation), neutral gray (same excitation) and white ( full excitation of all three cone types) also colors that are classifying named as achromatic colors.

Spectrum, as they occur in the wavelength- dependent refractive behind a prism, illustrated as a circle of bright colors, just include a few color perceptions. Visible radiation is electromagnetic radiation in the wavelength range from 380 nm to 780 nm Become colors triggered by colorant on the surface, must necessarily be a source of illumination available. Due to geographical proximity contrasts caused called simultaneous contrast, the effect of succession opponent colors successive contrast. Related to the simultaneous contrast are the colored shadows: An illuminated with green light object thus has a red shade.

Color impression of the people

Within a preamble color ( color ) color is also an expression of the distinguishing criteria of this quality. Grass has the color green, blood has the color red, a lemon, the color yellow. Clear glass is colorless (without custom color ). This perception of a quality of a visual impression created prior to the designation by words.

Words to describe impressions: blue, deep blue, pale blue, sky blue, red blue. Color differences can rename and so you can share your perceptions. In addition to the showing of material samples you can therefore also by words and colors of talk (so-called second signal system ). This is based on the conventional bargain, marked by generations and learned in childhood. In various human individual perception ( objectively ) the same named colors can be quite different. These individualities go to the partial or total failure of receptors to the color-vision deficiency.

Color names are for common understanding of the environment. There are also other non-verbal conventions: Red is at the traffic lights up and green is at the traffic below. In addition, influence the color effect and the impression of even color moods, the temporal and spatial prior effect, individual experience and training of perception.

Color names

Color terms

In all languages, there are a large number nuancierender words for individual colors. Sometimes " missing " in a language color names that others have. Examples are the late appearance of orange or magenta in German. The word meanings are also subject to social change. In German, meant brown in the 17th century rather dark purple to dark blue, as in the hymn down is light of the sun / the brown night breaks in strong. Also, the discussion point of the blue and green tones, as in the Asian region, leading to irritation in translations. Furthermore, there are approaches to express the availability of names for specific colors as a language universal in the form of a implikationalen hierarchy. Thus, all languages ​​have about a Schwarz/Dunkel- and white / light distinction if they offer three color terms, continues to have a term for red and so on.

There are separate color names for certain purposes, for example, applies only to human blonde, fawn, apply only to animal hair.

The emotional impact of color names uses the advertising of commercial products, since links to " attractive ", well-known objects or situations are available. The name Sahara as surface color of cars is symbolic, for example, for longing or width, and Ferrari red to evoke thoughts of speed and performance.

Undoubtedly, by culture, psyche and upbringing a symbolism of colors available, which sometimes is expressed in proverbs and reviews. In this sense, color names are also for feelings and vice versa.

Due to the influences of today's environmental know according to a study from the 2010s now four years old so many color names such as 100 years ago, eight- year-old.

Color coordinates

For the color representation on technological systems has several national and international standards and quasi- standards, such as " web colors " as part of the published by the World Wide Web Consortium CSS 3 specification. Color catalogs with color illustrations provide a connection between color names and two-dimensional color representation, such as the HKS color system or the German-speaking area of the RAL color catalog. In Germany, not so much, but still very common is the Pantone color system.

As described in Section perception, a color can be represented as a three-dimensional property. Therefore, technical color are usually given as a 3- tuple in a color space; Accordingly, there is often three primary colors or primary colors, to which the respective color space is constructed. Information such color coordinates as color coordinates, are little graphic, for technical applications ( for example, tolerance specifications in contracts ) necessary and inevitable. The only way to " color" Convert and color management is possible.

The specification of three color coordinates alone means nothing unless the corresponding color system is given in order to make intelligible statements. Especially in the case of a device color space, ie for the particular (individual ) device, this relationship is observed. On the same screen, the three bars look the same, it seems the colors (red, green, blue ) = { # 800080 } defined enough for a purple in the RGB system. When viewing the color stimulus thus produced at different ( side by side ) monitors, however, the bars appear different, especially if the monitors are not calibrated. For the examination of the used monitor for viewing this article and its setting, the bottom graph can serve. An LC - screens often affects even the viewing angle altering the perceived color impression.

Light color

So that color can be seen, the light is needed. This is caused by thermal motion of molecules or atoms, or by changes in the energy levels of the electron shell of atoms.

Body colors

Body color is that visual perception of objects, which is reflected by specific changes of the reflected spectrum due to absorption of substance-specific wavelengths of optical radiation or by scattering from the surface. In painting, the term is used object color and in the special case local color as opposed to overall tone. It can also by the structure of a physically based surface staining ( structural colors ), such as the iridescent patches on the wings of a butterfly to emerge.

Effect of

Irritating light of a particular spectrum of light the eye, has the except the simple sensation ( such as " cherry red ", " blue sky " ) and complex color-specific psychological effects in the central nervous system.

When people of the same cultural group composed by tradition and education many similarities, but there are also individual differences. Such psychological effects of color perception are - intuitively or consciously - used for effects in the artistic design as well as in the fashion and advertising industry. Help psychological color tests to achieve a desired effect. Color perception works exactly as other impressions on the psyche. Unusual coloration can also highlight details or hide and confuse by it.

Psychological color tests such as the Lüscher color test is attributed to be able to close by the preference for certain colors and color combinations on the personality of the subject. General color tests should also provide information as to what colors personalities react. Psychological effects of colors are accepted in many cultures, which is reflected in proverbs and sayings. Findings thereof are specifically used in advertising.

Cold or warm

Through the experience results in the simplest relations with the colors, as is the case for the temperature sensitivity.

• Warm colors: The warm season is determined by the yellow and red tones, open fire by glowing carbon particles has these colors. From the experience and the tradition, the colors are from yellow -green to purple to red in a " warm".
• Cold colors: The cold, blue water, the turquoise Eisschatten in winter and on icebergs, the " toxic " Blue Green repellent and act cool. Shades that are opposite to the warm colors on the color wheel are "cold" and accordingly perceived as called cold colors.

This relationship should not be confused with the color temperature of light sources physically defined. In addition, it is subject to individual and cultural differences in the perception of color. So Blue is now usually called cold color, but was classified in the Middle Ages as a warm and eg associated with the Virgin Mary.

Color groups

The effects and symbolic meanings of colors, also in relation to different cultural groups, can be found in the relevant articles to the colors and achromatic colors.

• → Red
• → Yellow
• → Blue

• → Purple
• → cyan, turquoise
• → Orange
• → Green

• → purple, magenta,
• → Brown, Olive,
• → White
• → Grey
• → Black

The visual system

The operation of the visual system in the central nervous system and especially in the brain in interaction with the feeling center is yet unexplored. On the other hand, the perception of different wavelengths image is perceived in the rods and cones of the retina not only for the emergence of responsible. The process of seeing color and shape of an object is also shaped by the fact that the cerebrum connects a sensation with an associated memory. The perceived color of an object is not always comparable to the metrological ( as physical ). Rather, the perceived image of the information currently recorded is covered, from the knowledge about this object.

In psychology, the term is naturalized memory colors when it comes to color perception. Objects with a typical color are so perceived by recourse to the value stored in memory prototypical color. So tomatoes are perceived in a more intense red as it corresponds to their actual appearance. A meadow appears even still green at dusk. Also, the blue sky is such an education, for the Romans was the sky "light", in the sense of bright

In colorimetry, this individualization lead to difficulties because two colors are not necessarily perceived the same by different personalities when the measurement has the same L * a * b * value. The CIE colorimetry ultimately relies on standard observer with the statistics and the light and color technology of the 1920s.

The perception of color affects psychologically in two ways

• Color evokes associations, ie ideas, mostly memories of things like red = fire, green = grass, yellow = lemon. More examples can be found in the table.
• Color invokes feelings (Color feeling feeling- quality look, feel, character ) out. These are expressed, if one turns nouns into adjectives or used from the outset adjectives that are able most likely to express feelings, red = dangerous, Green = toxic, Yellow = fresh. Color can activate past experiences on an emotional level.

Associations and feelings due to color perception, are included in the traditions of the culture in the respective ethnic area. After the " Empiricist theory of emotional effect of colors " are color emotions individually and implicit ( unconscious, not erinnerbar ) learned: These are especially feelings that the person on the basis of inherited instinctual structure and existence issues initially against certain ubiquitous " universal objects " or " universal situations " developed.

• Universal objects: blue sky, clear water, green vegetation, red fire, red blood ( "as the lifeblood " ), yellow sun, brown soil, brown to gray faeces, gray rocks, black fire residues.
• Universal situations are those in which man finds himself daily: dark (black ) night, light (white ) day.

Because the experience and education this emotion occupied beigibt things a certain ( culture of ) Colour, man already when he perceives the color alone develops feelings. The reaction to the color is then already impressed: Red alert, even if the supposedly related fires is missing and only the wall of the room is brightly painted red. This is equivalent to the learned conditioned reflexes in Pavlov's dogs through classical conditioning.

History of color

Color is a showy material property. Already the Stone Age people was this visual quality is known that is all primates own. Evidence of an active perception are the stone-age cave drawings in which people have reproduced the > popular < color of nature in their own creation with other types of dyes.

Artisanal activity requires the reproduction of color originals religious views of nature led to philosophical reflections on this material property and light phenomena. First notes of this kind can be found in classical China, in the Near East and especially in ancient times. The brilliant yellow of gold material, the substance of the gods, the reflection of the sun led to the desire this ending up. Attempts by the metal artisans and philosophical approaches to material conversion based on the theories of the elements promoted the desire expensive pigments different and cheaper in the same " color" to produce. According to the " foreseeable " property In particular, the " beautiful ", but his expensive gold - the color - " recreate " became the foundation and driving force of alchemy, the Hermetic Art.

Theories and doctrines to the color developed as any kind of science in conflict. For Democritus red particles were pointed and the green around.

In German-speaking countries had the biggest investigations and views by Johann Wolfgang von Goethe, supported by Philipp Otto Runge in his opposing view to Isaac Newton. Mention may be made, Hermann von Helmholtz, Ewald Hering, Wilhelm Ostwald and Johannes Itten or Harald Küppers. All Listed also the educational aspect of the " Ratgebens for color application " is available.

Were the basis of color, in terms of dye for the color of the first natural products. Blue was very expensive won ( rare as ) lapis lazuli powder. The blue color of substances served the vat with indigo. Purple from the secretion of the purple snail was the dye for emperors and kings. Red came from the cochineal scale insect. For brown, yellow and red earths were used. Representing are umber and sienna ( sienna ) to call from Italy. White was obtained as white lead from lead. For black soot suitable as a pigment for the difficult blackening of substances there was a special craft: the guild of dyers Black. Gold had in the Byzantine painting as sky color a metaphysical meaning.

In the 19th century, the color palette was expanded by new inorganic dyes and pigments. Berlin or Prussian blue, Rinmanns green, Schweinfurt green. Through imitation rare natural dyes in large quantities by industrial processes or newly created innovations dyeing options were expanded.

Due to the organic aniline colors ( coal tar dyes ) the number of available colorants has been greatly expanded. The natural pigments and dyes have been replaced by synthetic colors the growing need in art and business. The old names with regional references are partially retained until today. Naples yellow, Venetian red, Veronese green are examples of this.

In the 20th century have been enhanced by color photography and color printing, the possibilities of reproduction of natural templates through the " color volume " of paintings or artistic graphics ( Handkoloration ) addition. So, it has now also done research on the laws of color- accurate playback. The development of color television and digital photography in turn allowed improved color reproduction of natural colors, but the viewing habits changed also and require better color matching. Problems in implementing the colors of a template from the scanner for wide format for advertising purposes are newly perceived by " color training " in width of the population.

Due to the resulting higher demands of consumers, the color reproduction, the new technical possibilities and the research results, the " measurement" of the physiological size color for color metric developed.

Color models, color catalogs, color measurement

Color models

Different color models have been developed, in which colors are described quantitatively (using numbers), without necessarily present a intelligibility of the number triples with sensations. The specification (L = 75, a = 5, b = 33) does not call explicitly a perception of a color produced. In the color model, each color is represented as a point contained within a (often) three-dimensional color space - whose maximum extent is determined by the purity of the respective basic components. The models are conditioned and limited by the application whose color space should include all possible in the relevant art colors. In the event that different color reproduction techniques be used in a color workflow, this can only be partially converted into each other. Partial non-linear relationships are possible, but usually are matrices with support points between which must be interpolated linearly then. Different color spaces are not identical - the colors can therefore often only relative to each other, but absolutely not be reproduced identically. The most important case is the image of the RGB color space ( color, designed on the monitor ) to the CMYK color space of the printing inks.

Unlike the CIE Lab model, which is based on studies of human color perception, so that in all human-discernible colors are included. Therefore, " Lab " is often used in color reproduction as a reference color space, via which the other color spaces can be defined.

• RGB - basic colors: red, green and blue in proportions
• CMYK - Components: cyan, magenta, yellow (yellow ) and black (key)
• HSV - values: hue (hue ), saturation ( saturation ) and strength (value)
• CIELab - basic values: L ( lightness ) and the abstract values ​​a (red- green) and b (yellow- blue)
• XYZ: output color body of the CIE / IBKCIE (standard color space).
• YUV ( analog PAL and NTSC analog ), YDbDr in the analog SECAM, YIQ outdated, formerly used for analog NTSC
• YPbPr ( analog HDTV and analog component video)
• YCbCr (digital PAL / SECAM, NTSC digital, DVB, JPEG, MPEG, DVD - video)

Color catalogs

In addition to these only mathematically defined (quasi steady ) color space there are pattern collections, where material samples are comprised of defined colors. These are output depending on the industry as folders or pattern. Ultimately, forms the whole of the mixtures of different pigments in the surface staining ( printing industry ), or mixing with pigments or dyes ( plastic, textile industry) of a color catalog is also a three-dimensional rendering, possibly only one level. Examples are:

• Pantone
• HKS
• Hexachrome
• RAL
• NCS

Transitions between color spaces

Since color catalogs usually color values ​​are included in the three-dimensional system and color values ​​of the different models are defined, they can be converted into each. For each of the different color range of the associated color space conversion results are particularly in the edge regions is not always sufficient. To find a good approximation, one uses the color matching on the target substrate.

Mixing colors

If a large number of different colors are formed, then the desired color is mostly mixed from a small number of colors. Often, to meet the three primary colors, which are not usually available in real-life case available ..

• Additive color mixing: Based on Black ( All basic colors are missing, so each 0 % ), the result color is lighter, the more color is added. If all colors are added to 100 %, the result is bright and white. In this way, work as computer monitors. Typically, red, green and blue mixed in different proportions (RGB).
• Subtractive color mixing: Based on White (all colors to zero percent ), the result color is darker, the more color is added. When all the primary colors are added each to 100%, the resulting color is ( ideally) black. Based on this work as printers. Typical are the primary colors cyan, magenta and yellow ( yellow dt ), also referred to as CMY. Most still is added (CMYK ) black. The K stands for Key plate (Eng. key plate, the black printing plate ).
• The Integrated mixture was proposed by Küppers in his color theory to more realistic to consider the scattering factor of body colors, which remains unnoticed in the usual form of subtractive color mixing. In addition to the absorption of the color layers, the scattering in real surfaces is color- affecting, a theoretical analysis and a theoretical approach provides the Kubelka -Munk function.

Subtractive color mixing with magenta, cyan, yellow colorants

Color circle of Goethe, Original: Freies Deutsches Bishopric - Frankfurt Goethe Museum

The rhombohedron ( color bodies ) of color theory by Küppers

The color cube of the RGB color space and the CMY space

Spectral and mixed colors

• Kurzendfarben (short -wavelength side is 1): Blue
• Langendfarben (long -wavelength side is 1 ): Red
• Coloring ( in the long - and short-wavelength end no remission ): Green
• Means off-color (remission at both ends 1 but no remission in the middle): Veil, the purple colors.

Hue, brightness, colorful and achromatic colors

• The everyday language are black and white as " colors " again, but not referred to them as colored. Sometimes one uses the term achromatic colors to define the neutral gray scale.
• Are, the color (ie leave the an increasing color Nonferrous) impressively between the tint and saturation.

This distinction is due to the perception of color:

• Receptors to perception are the pins that exist in the human eye in three qualities of perception. Depending on the energy of the incident photons (corresponding to the optional wavelength) is activated by a chemical reaction, an electronic stimulus, it goes to the optic nerve. From the ratio of different irritation of the three receiving pins we take a dominant wavelength true hue. Depending on the intensity distribution of the stimuli we take the colors as saturated or had faded. This initial signal is a basis in the three-color theory. From herring, however, comes the four-color theory based on opponent color pairs " green-red " and " yellow-blue " and the rather led by the optic nerve and perceived in the cerebrum correlations than the outside of the body describes to-find physical situation. Gray, White or Black arise here as perceptions when all three cones are excited in almost the same quantity, so that there are no significant differences in nerve signal. The color dimensions color intensity and color saturation are thus due to the strength of the stimuli. Ultimately, one can formulate these relationships as a Act of vision.
• The rods are sensitive to light than the cones. If the amount of photons per unit time wears off, only the rod her charm are excited, continued in the optic nerve. In low light conditions ( night vision), in which the color pin trigger a stimulus to the brain is only information about the illumination. This information is in the original sense of the word " color-less " ( dark), it creates a " gray " impression ( At night all cats are gray ).
• If the amount of incident photons below the threshold of perception and the rod cells gives the impression "black" ( darkness ), physiologically better named as a proper gray.
• Excessive brightness ( in gloss or when looking into the sun ), so large number of photons overwrought both visual systems by glare. The " blinding " white causes pain as a warning response of the body. Since the rhodopsin recombined not sufficiently fast during intense glare temporary blindness can occur.

To be remarked that the cones and rods go back developmentally to the same light output responsive cells. This development led to the perception range of other animal species different from human. Bees are better equipped in the ultraviolet, their photoreceptor cells take shorter wavelength radiation ( higher-energy photons) true than man. In birds, the contrast sensitivity has been shown between red fruit and green foliage as important. For fish, the better perception of short-wave radiation is necessary because longer-wavelength portion of the solar light can be absorbed by water.

"Color" is possible on seeing the animals only in the figurative sense of the word.

The complex nature of the phenomenon of color is ultimately based on different levels of abstraction and seemingly contradictory statements. An example of this can be found at purple line.

• Physical consideration than the wavelength of light ( photon energy ),
• Three-dimensional color stimulus by the action on the pins (three-color theory ), which leads to three primaries in the CIE color space.
• Multi-layered effect of perceived color in the awareness of what presents itself as a Lab color space with equally spaced colors in the color theory.
• The interpretation of the perceived color and its effect on the psyche and through: color theory, harmony, color theory of types.