1.
Spectral color
–
A spectral color is a color that is evoked by a single wavelength of light in the visible spectrum, or by a relatively narrow band of wavelengths, also known as monochromatic light. Every wavelength of light is perceived as a spectral color, in a continuous spectrum. The spectrum is divided into named colors, though any division is somewhat arbitrary. Traditional colors include, red, orange, yellow, green, blue, and violet. The division used by Isaac Newton, in his wheel, was, red, orange, yellow, green, blue, indigo and violet. In modern divisions of the spectrum, indigo is often omitted, if luminance is counted, then spectral colors form a surface, otherwise their locus is a curve in a two-dimensional chromaticity space. Theoretically, only RGB-implemented colors which might be really spectral are its primaries, red, green, some samples in the table below provide only rough approximations of spectral and near-spectral colors. Ranges of wavelengths and frequencies are only approximate, among some of the colors that are not spectral colors are, Grayscale colors, such as white, gray, and black. Any color obtained by mixing a gray-scale color and another color, violet-red colors, which in color theory include line of purples colors, and other variations of purple and red. Impossible colors, which can not be seen under normal viewing of light, such as over-saturated colors or colors that are seemingly brighter than white
2.
Wavelength
–
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the waves shape repeats, and thus the inverse of the spatial frequency. Wavelength is commonly designated by the Greek letter lambda, the concept can also be applied to periodic waves of non-sinusoidal shape. The term wavelength is also applied to modulated waves. Wavelength depends on the medium that a wave travels through, examples of wave-like phenomena are sound waves, light, water waves and periodic electrical signals in a conductor. A sound wave is a variation in air pressure, while in light and other electromagnetic radiation the strength of the electric, water waves are variations in the height of a body of water. In a crystal lattice vibration, atomic positions vary, wavelength is a measure of the distance between repetitions of a shape feature such as peaks, valleys, or zero-crossings, not a measure of how far any given particle moves. For example, in waves over deep water a particle near the waters surface moves in a circle of the same diameter as the wave height. The range of wavelengths or frequencies for wave phenomena is called a spectrum, the name originated with the visible light spectrum but now can be applied to the entire electromagnetic spectrum as well as to a sound spectrum or vibration spectrum. In linear media, any pattern can be described in terms of the independent propagation of sinusoidal components. The wavelength λ of a sinusoidal waveform traveling at constant speed v is given by λ = v f, in a dispersive medium, the phase speed itself depends upon the frequency of the wave, making the relationship between wavelength and frequency nonlinear. In the case of electromagnetic radiation—such as light—in free space, the speed is the speed of light. Thus the wavelength of a 100 MHz electromagnetic wave is about, the wavelength of visible light ranges from deep red, roughly 700 nm, to violet, roughly 400 nm. For sound waves in air, the speed of sound is 343 m/s, the wavelengths of sound frequencies audible to the human ear are thus between approximately 17 m and 17 mm, respectively. Note that the wavelengths in audible sound are much longer than those in visible light, a standing wave is an undulatory motion that stays in one place. A sinusoidal standing wave includes stationary points of no motion, called nodes, the upper figure shows three standing waves in a box. The walls of the box are considered to require the wave to have nodes at the walls of the box determining which wavelengths are allowed, the stationary wave can be viewed as the sum of two traveling sinusoidal waves of oppositely directed velocities. Consequently, wavelength, period, and wave velocity are related just as for a traveling wave, for example, the speed of light can be determined from observation of standing waves in a metal box containing an ideal vacuum. In that case, the k, the magnitude of k, is still in the same relationship with wavelength as shown above
3.
Frequency
–
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as frequency, which emphasizes the contrast to spatial frequency. The period is the duration of time of one cycle in a repeating event, for example, if a newborn babys heart beats at a frequency of 120 times a minute, its period—the time interval between beats—is half a second. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as vibrations, audio signals, radio waves. For cyclical processes, such as rotation, oscillations, or waves, in physics and engineering disciplines, such as optics, acoustics, and radio, frequency is usually denoted by a Latin letter f or by the Greek letter ν or ν. For a simple motion, the relation between the frequency and the period T is given by f =1 T. The SI unit of frequency is the hertz, named after the German physicist Heinrich Hertz, a previous name for this unit was cycles per second. The SI unit for period is the second, a traditional unit of measure used with rotating mechanical devices is revolutions per minute, abbreviated r/min or rpm. As a matter of convenience, longer and slower waves, such as ocean surface waves, short and fast waves, like audio and radio, are usually described by their frequency instead of period. Spatial frequency is analogous to temporal frequency, but the axis is replaced by one or more spatial displacement axes. Y = sin = sin d θ d x = k Wavenumber, in the case of more than one spatial dimension, wavenumber is a vector quantity. For periodic waves in nondispersive media, frequency has a relationship to the wavelength. Even in dispersive media, the frequency f of a wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave. In the special case of electromagnetic waves moving through a vacuum, then v = c, where c is the speed of light in a vacuum, and this expression becomes, f = c λ. When waves from a monochrome source travel from one medium to another, their remains the same—only their wavelength. For example, if 71 events occur within 15 seconds the frequency is, the latter method introduces a random error into the count of between zero and one count, so on average half a count. This is called gating error and causes an error in the calculated frequency of Δf = 1/, or a fractional error of Δf / f = 1/ where Tm is the timing interval. This error decreases with frequency, so it is a problem at low frequencies where the number of counts N is small, an older method of measuring the frequency of rotating or vibrating objects is to use a stroboscope
4.
Hertz
–
The hertz is the unit of frequency in the International System of Units and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide proof of the existence of electromagnetic waves. Hertz are commonly expressed in SI multiples kilohertz, megahertz, gigahertz, kilo means thousand, mega meaning million, giga meaning billion and tera for trillion. Some of the units most common uses are in the description of waves and musical tones, particularly those used in radio-. It is also used to describe the speeds at which computers, the hertz is equivalent to cycles per second, i. e. 1/second or s −1. In English, hertz is also used as the plural form, as an SI unit, Hz can be prefixed, commonly used multiples are kHz, MHz, GHz and THz. One hertz simply means one cycle per second,100 Hz means one hundred cycles per second, and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, the rate of aperiodic or stochastic events occur is expressed in reciprocal second or inverse second in general or, the specific case of radioactive decay, becquerels. Whereas 1 Hz is 1 cycle per second,1 Bq is 1 aperiodic radionuclide event per second, the conversion between a frequency f measured in hertz and an angular velocity ω measured in radians per second is ω =2 π f and f = ω2 π. This SI unit is named after Heinrich Hertz, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, the hertz is named after the German physicist Heinrich Hertz, who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission in 1930, the term cycles per second was largely replaced by hertz by the 1970s. One hobby magazine, Electronics Illustrated, declared their intention to stick with the traditional kc. Mc. etc. units, sound is a traveling longitudinal wave which is an oscillation of pressure. Humans perceive frequency of waves as pitch. Each musical note corresponds to a frequency which can be measured in hertz. An infants ear is able to perceive frequencies ranging from 20 Hz to 20,000 Hz, the range of ultrasound, infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtoHz into the terahertz range and beyond. Electromagnetic radiation is described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation is measured in kilohertz, megahertz, or gigahertz
5.
Water
–
Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
6.
SRGB
–
SRGB is the standard RGB color space created cooperatively by HP and Microsoft in 1996 for use on monitors, printers and the Internet, and subsequently standardized by the IEC as IEC 61966-2-1,1999. It is often used as the color space for images that do not contain any color space information. This specification allowed sRGB to be displayed on typical CRT monitors of the time. SRGB defines the chromaticities of the red, green, and blue primaries, the gamut of chromaticities that can be represented in sRGB is the color triangle defined by these primaries. SRGB also defines a transformation between the intensity of these primaries and the actual number stored. The curve is similar to the response of a CRT display. It is more important to replicate this curve than the primaries to get correct display of an sRGB image and this nonlinear conversion means that sRGB is a reasonably efficient use of the values in an integer-based image file to display human-discernible light levels. Unlike most other RGB color spaces, the sRGB gamma cannot be expressed as a numerical value. The overall gamma is approximately 2.2, consisting of a section near black, and a non-linear section elsewhere involving a 2.4 exponent. The purpose of the section is so the curve does not have an infinite slope at zero. The CIE XYZ values must be scaled so that the Y of D65 is 1.0 and this is usually true but some color spaces use 100 or other values. The first step in the calculation of sRGB from CIE XYZ is a linear transformation, = It is important to note that these linear RGB values are not the final result as they have not been adjusted for the gamma correction. SRGB was designed to reflect a typical real-world monitor with a gamma of 2.2, and the following formula transforms the linear RGB values into sRGB. If values in the range 0 to 255 are required, e. g. for video display or 8-bit graphics, the values are usually clipped to the 0 to 1 range. This clipping can be done before or after this gamma calculation, again the sRGB component values R s r g b, G s r g b, B s r g b are in the range 0 to 1. Followed by a multiplication of the linear values to get XYZ, = It is often casually stated that the decoding gamma for sRGB data is 2.2. The transformation was designed to approximate a gamma of about 2.2, but with a portion near zero to avoid having an infinite slope at K =0. The continuity condition for the curve C l i n e a r which is defined above as a function of C s r g b, is γ = K0 ϕ
7.
Red
–
Red is the color at the longer-wavelengths end of the spectrum of visible light next to orange, at the opposite end from violet. Red color has a predominant light wavelength of roughly 620–740 nanometers, light with a longer wavelength than red but shorter than terahertz radiation and microwave is called infrared. Red is one of the secondary colors, resulting from the combination of yellow. Traditionally, it was viewed as a primary colour, along with yellow and blue, in the RYB color space and traditional color wheel formerly used by painters. Reds can vary in shade from light pink to very dark maroon or burgundy. Red is the color of cyan. In nature, the red color of blood comes from hemoglobin, the red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. It also causes the red color of the planet Mars, the color of autumn leaves is caused by pigments called anthocyanins, which are produced towards the end of summer, when the green chlorophyll is no longer produced. One to two percent of the population has red hair, the color is produced by high levels of the reddish pigment pheomelanin. Since red is the color of blood, it has historically been associated with sacrifice, danger, modern surveys in the United States and Europe show red is also the color most commonly associated with heat, activity, passion, sexuality, anger, love and joy. In China, India and many other Asian countries it is the color of symbolizing happiness, since the 19th century, red has also been associated with socialism and communism. The word red is derived from the Old English rēad, the word can be further traced to the Proto-Germanic rauthaz and the Proto-Indo European root rewdʰ-. In Sanskrit, the word means red or blood. In the Akkadian language of Ancient Mesopotamia and in the modern Inuit language of Inuit, the words for colored in Latin and Spanish both also mean red. In Portuguese the word for red is vermelho, which comes from Latin vermiculus, in the Russian language, the word for red, Кра́сный, comes from the same old Slavic root as the words for beautiful—красивый and excellent—прекрасный. Thus Red Square in Moscow, named long before the Russian Revolution, in heraldry, the word gules is used for red. Red can vary in hue from orange-red to violet-red, and for each hue there is a variety of shades and tints. Red hematite powder was found scattered around the remains at a grave site in a Zhoukoudian cave complex near Beijing
8.
Green
–
Green is the color between blue and yellow on the spectrum of visible light. It is evoked by light with a predominant wavelength of roughly 495–570 nm, the modern English word green comes from the Middle English and Anglo-Saxon word grene, from the same Germanic root as the words grass and grow. It is the color of living grass and leaves and as a result is the color most associated with springtime, growth, by far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into chemical energy. Many creatures have adapted to their environments by taking on a green hue themselves as camouflage. Several minerals have a color, including the emerald, which is colored green by its chromium content. In surveys made in Europe and the United States, green is the color most commonly associated with nature, life, health, youth, spring, hope and envy. In Europe and the U. S. green is associated with death, sickness, or the devil. In the Middle Ages and Renaissance, when the color of clothing showed the social status, green was worn by merchants, bankers. The Mona Lisa by Leonardo da Vinci wears green, showing she is not from a noble family, Green is also the traditional color of safety and permission, a green light means go ahead, a green card permits permanent residence in the United States. It is the most important color in Islam and it was the color of the banner of Muhammad, and is found in the flags of nearly all Islamic countries, and represents the lush vegetation of Paradise. It is also associated with the culture of Gaelic Ireland. Because of its association with nature, it is the color of the environmental movement, political groups advocating environmental protection and social justice describe themselves as part of the Green movement, some naming themselves Green parties. This has led to campaigns in advertising, as companies have sold green, or environmentally friendly. The word green comes from the Middle English and Old English word grene, which, like the German word grün, has the same root as the words grass and grow. It is from a Common Germanic *gronja-, which is reflected in Old Norse grænn, Old High German gruoni, ultimately from a PIE root *ghre- to grow. The first recorded use of the word as a term in Old English dates to ca. Latin with viridis also has a genuine and widely used term for green, related to virere to grow and ver spring, it gave rise to words in several Romance languages, French vert, Italian verde. Likewise the Slavic languages with zelenъ, Ancient Greek also had a term for yellowish, pale green – χλωρός, chloros, cognate with χλοερός verdant and χλόη the green of new growth
9.
Blue
–
Blue is the colour between violet and green on the optical spectrum of visible light. Human eyes perceive blue when observing light with a wavelength between 450 and 495 nanometres, which is between 4500 and 4950 ångströms. Blues with a frequency and thus a shorter wavelength gradually look more violet, while those with a lower frequency. Pure blue, in the middle, has a wavelength of 470 nanometers, in painting and traditional colour theory, blue is one of the three primary colours of pigments, along with red and yellow, which can be mixed to form a wide gamut of colours. Red and blue mixed together form violet, blue and yellow together form green, Blue is also a primary colour in the RGB colour model, used to create all the colours on the screen of a television or computer monitor. The clear sky and the sea appear blue because of an optical effect known as Rayleigh scattering. When sunlight passes through the atmosphere, the wavelengths are scattered more widely by the oxygen and nitrogen molecules. An optical effect called Tyndall scattering, similar to Rayleigh scattering, explains blue eyes, distant objects appear more blue because of another optical effect called atmospheric perspective. Blue has been used for art and decoration since ancient times and it is the most important color in Judaism. In the Middle Ages, cobalt blue was used to colour the stained glass windows of cathedrals, beginning in the 9th century, Chinese artists used cobalt to make fine blue and white porcelain. Blue dyes for clothing were made from woad in Europe and indigo in Asia, in 1828 a synthetic ultramarine pigment was developed, and synthetic blue dyes and pigments gradually replaced mineral pigments and vegetable dyes. Pierre-Auguste Renoir, Vincent van Gogh and other late 19th century painters used ultramarine and cobalt blue not just to depict nature, in the late 18th century and 19th century, blue became a popular colour for military uniforms and police uniforms. In the 20th century, because blue was associated with harmony, it was chosen as the colour of the flags of the United Nations. Surveys in the US and Europe show that blue is the colour most commonly associated with harmony, faithfulness, confidence, distance, infinity, the imagination, cold, and sometimes with sadness. In US and European public opinion polls it is the most popular colour, Blue is the colour of light between violet and green on the visible spectrum. Blues also vary in shade or tint, darker shades of blue contain black or grey, darker shades of blue include ultramarine, cobalt blue, navy blue, and Prussian blue, while lighter tints include sky blue, azure, and Egyptian blue. Today most blue pigments and dyes are made by a chemical process, the modern English word blue comes from Middle English bleu or blewe, from the Old French bleu, a word of Germanic origin, related to the Old High German word blao. In heraldry, the azure is used for blue
10.
CMYK color model
–
The CMYK color model is a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four used in some color printing, cyan, magenta, yellow. Though it varies by print house, press operator, press manufacturer, the K in CMYK stands for key because in four-color printing, cyan, magenta and yellow printing plates are carefully keyed, or aligned, with the key of the black key plate. Some sources suggest that the K in CMYK comes from the last letter in black and was chosen because B already means blue. Some sources claim this explanation, although useful as a mnemonic, is incorrect, the CMYK model works by partially or entirely masking colors on a lighter, usually white, background. The ink reduces the light that would otherwise be reflected, such a model is called subtractive because inks subtract brightness from white. In additive color models such as RGB, white is the combination of all primary colored lights. In the CMYK model, it is the opposite, white is the color of the paper or other background. To save cost on ink, and to produce deeper black tones, unsaturated and dark colors are produced by using black ink instead of the combination of cyan, magenta, with halftoning, a full continuous range of colors can be produced. To improve print quality and reduce moiré patterns, the screen for each color is set at a different angle. Common reasons for using black ink include, In traditional preparation of color separations, in some cases a black keyline was used when it served as both a color indicator and an outline to be printed in black. Because usually the black plate contained the keyline, the K in CMYK represents the keyline or black plate, also sometimes called the key plate. A combination of 100% cyan, magenta, and yellow inks soaks the paper with ink, making it slower to dry, causing bleeding, adding black ink absorbs more light and yields much better blacks. Using black ink is less expensive than using the corresponding amounts of colored inks. When a very dark area is desirable, a colored or gray CMY bedding is applied first, then a black layer is applied on top, making a rich, deep black. A black made with just CMY inks is sometimes called a composite black, the amount of black to use to replace amounts of the other ink is variable, and the choice depends on the technology, paper and ink in use. Processes called under color removal, under addition, and gray component replacement are used to decide on the final mix. CMYK or process color printing is contrasted with spot color printing, some printing presses are capable of printing with both four-color process inks and additional spot color inks at the same time
11.
Magenta
–
Magenta is a color that is variously defined as purplish-red, reddish-purple, or mauvish-crimson. On computer screens, it is made by mixing equal amounts of blue, on color wheels of the RGB and CMY color models, it is located midway between red and blue. It is the color of green. It is one of the four colors of ink used in printing and by an inkjet printer, along with cyan, yellow. The tone of magenta used in printing is called printers magenta, Magenta was first introduced as the color of a new aniline dye called fuchsine, patented in 1859 by the French chemist François-Emmanuel Verguin. Its name was changed the year to magenta, to celebrate a victory of the French and Sardinian army at the Battle of Magenta on June 4,1859. The web color magenta is called fuchsia. Magenta is a color, meaning that it is not found in the visible spectrum of light. Rather, it is physiologically and psychologically perceived as the mixture of red and violet/blue light, with the absence of green. In the RGB color system, used to all the colors on a television or computer display, magenta is a secondary color, made by combining equal amounts of red. In this system, magenta is the color of green. In the CMYK color model, used in printing, it is one of the three primary colors, along with cyan and yellow, used to print all the rest of the colors. If magenta, cyan, and yellow are printed on top of each other on a page, in this model, magenta is the complementary color of green, and these two colors have the highest contrast and the greatest harmony. If combined, green and magenta ink will look dark gray or black, the magenta used in color printing, sometimes called process magenta, is a darker shade than the color used on computer screens. A purple hue in terms of theory, magenta is evoked by light having less power in green wavelengths than in blue/violet. In the Munsell color system, magenta is called red–purple, if the spectrum is wrapped to form a color wheel, magenta appears midway between red and violet. Violet and red, the two components of magenta, are at opposite ends of the spectrum and have very different wavelengths. The additive secondary color magenta, as noted above, is made by combining violet and red light at equal intensity, in optics, fuchsia and magenta are essentially the same color
12.
Yellow
–
Yellow is the color between green and orange on the spectrum of visible light. It is evoked by light with a predominant wavelength of roughly 570–590 nm, in traditional color theory, used in painting, and in the subtractive color system, used in color printing, yellow is a primary color. In the RGB color model, used to create colors on television and computer screens, yellow is made by combining red, the word yellow comes from the Old English geolu, geolwe, meaning yellow, yellowish, derived from the Proto-Germanic word gelwaz yellow. It has the same Indo-European base, gʰel-, as the gold and yell. In Iran it has connotations of pallor/sickness, but also wisdom and it plays an important role in Asian culture, particularly in China, where it is seen as the color of happiness, glory, wisdom, harmony, and culture. The word yellow comes from the Old English geolu, geolwe, meaning yellow, yellowish and it has the same Indo-European base, gʰel-, as the words gold and yell, gʰel- means both bright and gleaming, and to cry out. The English term is related to other Germanic words for yellow, namely Scots yella, East Frisian jeel, West Frisian giel, Dutch geel, German gelb, and Swedish and Norwegian gul. According to the Oxford English Dictionary, the oldest known use of word in English is from The Epinal Glossary in 700. Yellow, in the form of yellow pigment made from clay, was one of the first colors used in prehistoric cave art. The cave of Lascaux has an image of a horse colored with yellow estimated to be 17,300 years old, in Ancient Egypt, yellow was associated with gold, which was considered to be imperishable, eternal and indestructible. The skin and bones of the gods were believed to be made of gold, the Egyptians used yellow extensively in tomb paintings, they usually used either yellow ochre or the brilliant orpiment, though it was made of arsenic and was highly toxic. A small paintbox with orpiment pigment was found in the tomb of King Tutankhamun, men were always shown with brown faces, women with yellow ochre or gold faces. The ancient Romans used yellow in their paintings to represent gold and it is found frequently in the murals of Pompeii. During the Post-Classical period, yellow became firmly established as the color of Judas Iscariot, from this connection, yellow also took on associations with envy, jealousy and duplicity. The tradition started in the Renaissance of marking non-Christian outsiders, such as Jews, in 16th century Spain, those accused of heresy and who refused to renounce their views were compelled to come before the Spanish Inquisition dressed in a yellow cape. The color yellow has been associated with moneylenders and finance. The National Pawnbrokers Associations logo depicts three golden spheres hanging from a bar, referencing the three bags of gold that the saint of pawnbroking, St. Nicholas, holds in his hands. Additionally, the symbol of three golden orbs is found in the coat of arms of the House of Medici, a fifteenth century Italian dynasty of bankers and lenders
13.
Black
–
Black is the darkest color resulting from the absence or complete absorption of light. Like white and grey, it is a color, literally a color without hue. It is one of the four colors in the CMYK color model, along with cyan, yellow. Black is often used to represent darkness, it is the symbolic opposite of white, Black was one of the first colors used by artists in neolithic cave paintings. In the 14th century, it began to be worn by royalty and it became the color worn by English romantic poets, businessmen and statesmen in the 19th century, and a high fashion color in the 20th century. In the Roman Empire, it became the color of mourning, according to surveys in Europe and North America, it is the color most commonly associated with mourning, the end, secrets, magic, force, violence, evil, and elegance. More distant cognates include Latin flagrare, and Ancient Greek phlegein, the Ancient Greeks sometimes used the same word to name different colors, if they had the same intensity. Kuanos could mean both dark blue and black, the Ancient Romans had two words for black, ater was a flat, dull black, while niger was a brilliant, saturated black. Ater has vanished from the vocabulary, but niger was the source of the country name Nigeria the English word Negro, old High German also had two words for black, swartz for dull black and blach for a luminous black. These are parallelled in Middle English by the terms swart for dull black, swart still survives as the word swarthy, while blaek became the modern English black. In heraldry, the used for the black color is sable, named for the black fur of the sable. Black was one of the first colors used in art, the Lascaux Cave in France contains drawings of bulls and other animals drawn by paleolithic artists between 18,000 and 17,000 years ago. They began by using charcoal, and then made more vivid black pigments by burning bones or grinding a powder of manganese oxide, for the ancient Egyptians, black had positive associations, being the color of fertility and the rich black soil flooded by the Nile. It was the color of Anubis, the god of the underworld, who took the form of a black jackal, and offered protection against evil to the dead. For the ancient Greeks, black was also the color of the underworld, separated from the world of the living by the river Acheron and those who had committed the worst sins were sent to Tartarus, the deepest and darkest level. In the center was the palace of Hades, the king of the underworld, Black was one of the most important colors used by ancient Greek artists. In the 6th century BC, they began making pottery and later red figure pottery. In black-figure pottery, the artist would paint figures with a clay slip on a red clay pot
14.
HSL and HSV
–
HSL and HSV are the two most common cylindrical-coordinate representations of points in an RGB color model. The two representations rearrange the geometry of RGB in an attempt to be intuitive and perceptually relevant than the cartesian representation. Developed in the 1970s for computer applications, HSL and HSV are used today in color pickers, in image editing software. HSL stands for hue, saturation, and lightness, and is often called HLS. HSV stands for hue, saturation, and value, and is often called HSB. A third model, common in computer applications, is HSI. However, while typically consistent, these definitions are not standardized, note that while hue in HSL and HSV refers to the same attribute, their definitions of saturation differ dramatically. As a result, each unique RGB device has unique HSL and HSV absolute color spaces to accompany it, other more computationally intensive models, such as CIELAB or CIECAM02, are said to better achieve these goals. In each geometry, the vertical axis comprises the neutral, achromatic, or gray colors, ranging from black at lightness 0 or value 0, the bottom, to white at lightness 1 or value 1. These saturated colors have lightness ½ in HSL, while in HSV they have value 1, mixing these pure colors with black—producing so-called shades—leaves saturation unchanged. In HSL, saturation is also unchanged by tinting with white, in HSV, tinting alone reduces saturation. Confusingly, such diagrams usually label this radial dimension saturation, blurring or erasing the distinction between saturation and chroma, as described below, computing chroma is a helpful step in the derivation of each model. Most televisions, computer displays, and projectors produce colors by combining red, green, furthermore, neither additive nor subtractive color models define color relationships the same way the human eye does. For example, imagine we have an RGB display whose color is controlled by three sliders ranging from 0–255, one controlling the intensity of each of the red, green, consequently, these models and similar ones have become ubiquitous throughout image editing and graphics software since then. Some of their uses are described below, nonetheless, it is worth reviewing those definitions before leaping into the derivation of our models. Hue The attribute of a visual sensation according to which an area appears to be similar to one of the colors, red, yellow, green. Radiance The radiant power of passing through a particular surface per unit solid angle per unit projected area. Luminance The radiance weighted by the effect of each wavelength on a human observer
15.
Hue
–
Orange and violet are the other hues, for a total of six, as in the rainbow, red, orange, yellow, green, blue, violet. The other color appearance parameters are colorfulness, chroma, saturation, lightness, usually, colors with the same hue are distinguished with adjectives referring to their lightness and/or colorfulness, such as with light blue, pastel blue, vivid blue. Exceptions include brown, which is a dark orange, in painting color theory, a hue refers to a pure color—one without tint or shade. A hue is an element of the color wheel, hues are first processed in the brain in areas in the extended V4 called globs. Hue is the component of the polar representation, while chroma is the radial component. Specifically, in CIELAB h a b = a t a n 2, while, analogously, in CIELUV h u v = a t a n 2 = a t a n 2, where, atan2 is a two-argument inverse tangent. Preucil describes a color hexagon, similar to a trilinear plot described by Evans, Hanson, and Brewer, to place red at 0°, green at 120°, and blue at 240°, h r g b = a t a n 2. Equivalently, one may solve tan =3 ⋅2 ⋅ R − G − B, Preucil used a polar plot, which he termed a color circle. Using R, G, and B, one may compute hue angle using the scheme, determine which of the six possible orderings of R, G. Note that in case the formula contains the fraction M − L H − L, where H is the highest of R, G, and B, L is the lowest. This is referred to as the Preucil hue error and was used in the computation of mask strength in photomechanical color reproduction, the formulae used are those in the table above. The hues exhibited by caramel colorings and beers are fairly limited in range, the Linner hue index is used to quantify the hue of such products. Replacements are often used for chromium, cadmium and alizarin, dominant wavelength is a physical analog to the perceptual attribute hue. On a chromaticity diagram, a line is drawn from a point through the coordinates of the color in question. There are two ways in which hue difference is quantified. The first is the difference between the two hue angles. The symbol for expression of hue difference is Δ h a b in CIELAB. The other is computed as the total color difference after Lightness and Chroma differences have been accounted for, its symbol is Δ H a b ∗ in CIELAB
16.
Colorfulness
–
Colorfulness or saturation in colorimetry and color theory refers to the perceived intensity of a specific color. Colorfulness is the visual sensation according to which the color of an area appears to be more or less chromatic. Chroma is the relative to the brightness of a similarly illuminated area that appears to be white or highly transmitting. Therefore, chroma should not be confused with colorfulness, saturation is the colorfulness of a color relative to its own brightness. A highly colorful stimulus is vivid and intense, while a less colorful stimulus appears more muted, with no colorfulness at all, a color is a “neutral” gray. Any color can be described using three color appearance parameters — colorfulness, lightness, and hue, saturation is one of three coordinates in the HSL and HSV color spaces. The saturation of a color is determined by a combination of light intensity, the purest color is achieved by using just one wavelength at a high intensity, such as in laser light. If the intensity drops, then as a result the saturation drops, to desaturate a color of given intensity in a subtractive system, one can add white, black, gray, or the hues complement. CIELUV The chroma normalized by the lightness, s u v = C u v ∗ L ∗ =132 +2 where is the chromaticity of the white point, and chroma is defined below. Nevertheless, this provides a reasonable predictor of saturation. S a b = C a b ∗ C a b ∗2 + L ∗2100 % where Sab is the saturation, L* the lightness and C*ab is the chroma of the color. CIECAM02 The square root of the colorfulness divided by the brightness, M is proportional to the chroma C, thus the CIECAM02 definition bears some similarity to the CIELUV definition. An important difference is that the CIECAM02 model accounts for the conditions through the parameter FL. Different color spaces, such as CIELAB or CIELUV may be used, the naïve definition of saturation does not specify its response function. However, both color spaces are nonlinear in terms of perceived color differences. It is also possible—and sometimes desirable—to define a quantity that is linearized in term of the psychovisual perception. The transformation of to is given by, C a b ∗ = a ∗2 + b ∗2 h a b = arctan b ∗ a ∗ and analogously for CIE L*C*h. The chroma in the CIE L*C*h and CIE L*C*h coordinates has the advantage of being more psychovisually linear, and therefore, chroma in CIE1976 L*a*b* and L*u*v* color spaces is very much different from the traditional sense of saturation
17.
Brightness
–
Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target and it is not necessarily proportional to luminance. This is a subjective attribute/property of an object being observed and one of the color appearance parameters of color appearance models, brightness refers to an absolute term and should not be confused with Lightness. The adjective bright derives from an Old English beorht with the same meaning via metathesis giving Middle English briht, the word is from a Common Germanic *berhtaz, ultimately from a PIE root with a closely related meaning, *bhereg- white, bright. Brightness was formerly used as a synonym for the term luminance. As defined by the US Federal Glossary of Telecommunication Terms, brightness should now be used only for non-quantitative references to physiological sensations and perceptions of light, a given target luminance can elicit different perceptions of brightness in different contexts, see, for example, Whites illusion. With regard to stars, brightness is quantified as apparent magnitude, brightness is, at least in some respects, the antonym of darkness. The United States Federal Trade Commission has assigned a meaning to brightness when applied to lamps. When appearing on light bulb packages, brightness means Luminous flux, Luminous flux is the total amount of light coming from a source, such as a lighting device. Luminance, the meaning of brightness, is the amount of light per solid angle coming from an area. The table below shows the ways of indicating the amount of light. The term brightness is used in discussions of sound timbres. Luma Luminance Luminosity Media related to brightness at Wikimedia Commons Poyntons Color FAQ
18.
Subtractive color
–
The color that a surface displays depends on which parts of the visible spectrum are not absorbed and therefore remain visible. Subtractive color systems start with light, presumably white light, colored inks, paints, or filters between the watchers and the light source or reflective surface subtract wavelengths from the light, giving it color. If the incident light is other than white, our visual mechanisms are able to compensate well, conversely, additive color systems start with darkness. Light sources of various wavelengths are added in proportions to produce a range of colors. Usually, three colors are combined to stimulate humans’ trichromatic color vision, sensed by the three types of cone cells in the eye, giving an apparently full range. RYB is the standard set of subtractive primary colors used for mixing pigments. It is used in art and art education, particularly in painting and it predated modern scientific color theory. Red, yellow, and blue are the colors of the standard color wheel. The secondary colors, violet, orange, and green make up another triad, formed by mixing equal amounts of red and blue, red and yellow, in color printing, the usual primary colors are cyan, magenta and yellow. Cyan is the complement of red, meaning that the cyan serves as a filter that absorbs red, the amount of cyan applied to a white sheet of paper controls how much of the red in white light will be reflected back from the paper. Ideally, the cyan is completely transparent to green and blue light and has no effect on those parts of the spectrum, magenta is the complement of green, and yellow the complement of blue. Combinations of different amounts of the three can produce a range of colors with good saturation. In inkjet color printing and typical mass production photomechanical printing processes, additive color Color mixing Color motion picture film Color space Color theory Primary color Berns, Roy S. Billmeyer and Saltzmans Principles of Color Technology, 3rd edition. Stroebel, Leslie, John Compton, Ira Current, and Richard Zakia, basic Photographic Materials and Processes, 2nd edition. CS1 maint, Multiple names, authors list Wyszecki, Günther & W. S. Stiles, colour Science, Concept and Methods, Quantitative Data and Formulae. Stanford University CS178 interactive Flash demo comparing additive and subtractive color mixing
19.
Primary color
–
A set of primary colors is a small, arbitrary set of pigmented physical media, lights or purely abstract elements of a mathematical colorspace model. Distinct colors from a larger gamut can be specified in terms of a mixture of colors which facilitates technological applications such as painting, electronic displays. Any small set of pigments or lights are imperfect physical primary colors in that they cannot be mixed to yield all possible colors that can be perceived by the color vision system. In an additive set of colors, as in coincident projected lights or in electronic visual displays, in a subtractive set of colors, as in mixing of pigments or dyes for printing, the colors magenta, yellow and cyan are normally used. See RGB color model, and CMYK color model for more on these sets of primary colors. Primary colors are not a property of light but are related to the color vision system in animals. The human eye normally contains three types of color photoreceptors that are associated with specialized cone cells. Each photoreceptor responds to different ranges of the electromagnetic spectrum. Humans and other species with three types of color photoreceptor are known as trichromats. Color appearance models like CIECAM02 describe color more generally in six dimensions, most placental mammals other than primates have only two types of color photoreceptor and are therefore dichromats while birds and marsupials are tetrachromats with four color photoreceptor types. There is no peer reviewed scholarly work that has confirmed the existence of a functional human tetrachromat though they are suspected to exist. Demonstrating improved spectral discrimination in any animal can be difficult since complex sets of neurons affect color perception in ways that are difficult to interrogate. Before the nature of colorimetry and visual physiology were well understood a number of color models assigned primary colors to different hues. Young originally proposed red, green and violet, and Maxwell changed violet to blue, Helmholtz proposed a slightly red, a vegetation-green, slightly yellowish. In modern understanding, human cells do not correspond precisely to a specific set of primary colors. There are hundreds of available pigments for visual artists to use. A common approach is to use just a palette of pigments that can be physically mixed to any color that the artist desires in the final work. Contemporary classical realists have often advocated that a palette of white, red, yellow
20.
Additive color
–
Additive color is color created by mixing a number of different light colors, with shades of red, green, and blue being the most common primary colors used in additive color system. Computer monitors and televisions are the most common examples of additive color, the colored sub-pixels do not overlap on the screen, but when viewed from a normal distance they overlap and blend on the eyes retina, producing the same result as external superimposition. Another example of color can be found in the overlapping projected colored lights often used in theatrical lighting for plays, concerts, circus shows. The full gamut of color available in any additive color system is defined by all the combinations of all the possible luminosities of each primary color in that system. In chromaticity space, the gamut is a convex polygon with corners at the primaries. For three primaries, it is a triangle, for example, in subtractive color systems, green is a combination of yellow and cyan, in additive color, red plus green makes yellow. Additive color is a result of the way the eye detects color, there is a vast difference between a pure spectral yellow light, with a wavelength of approximately 580 nm, and a mixture of red and green light. However, both stimulate our eyes in a manner, so we do not detect that difference. Systems of additive color are motivated by the Young–Helmholtz theory of color vision. For his experimental work on the subject, James Clerk Maxwell is sometimes credited as being the father of additive color. He had the photographer Thomas Sutton photograph a tartan ribbon on black-and-white film three times, first with a red, then green, then blue color filter over the lens. When brought into alignment, the three formed a full color image, thus demonstrating the principles of additive color. The following chart demonstrates an example of the mixing and perception of additive primaries, to fully understand the process, it should be demonstrated how dull colors are obtained using cyan, magenta, and yellow instead of red, green, and blue. Color mixing Color space Color theory Color motion picture film Kinemacolor Prizma Color RGB color model Subtractive color Technicolor William Friese-Greene RGB, http, //www. edinphoto. org. uk/1_P/1_photographers_maxwell. htm - Photos and stories from the James Clerk Maxwell Foundation. Stanford University CS178 interactive Flash demo comparing additive and subtractive color mixing
21.
RGB color model
–
The RGB color model is an additive color model in which red, green and blue light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three primary colors, red, green and blue. Before the electronic age, the RGB color model already had a theory behind it. Thus an RGB value does not define the same color across devices without some kind of color management, typical RGB input devices are color TV and video cameras, image scanners, video games, and digital cameras. Typical RGB output devices are TV sets of technologies, computer and mobile phone displays, video projectors, multicolor LED displays. Color printers, on the hand are not RGB devices. This article discusses concepts common to all the different color spaces that use the RGB color model, to form a color with RGB, three light beams must be superimposed. Each of the three beams is called a component of color, and each of them can have an arbitrary intensity, from fully off to fully on. The RGB color model is additive in the sense that the three beams are added together, and their light spectra add, wavelength for wavelength. This is essentially opposite to the color model that applies to paints, inks, dyes. When the intensities for all the components are the same, the result is a shade of gray, darker or lighter depending on the intensity. When the intensities are different, the result is a colorized hue, a secondary color is formed by the sum of two primary colors of equal intensity, cyan is green+blue, magenta is red+blue, and yellow is red+green. The RGB color model itself does not define what is meant by red, green and blue colorimetrically, and so the results of mixing them are not specified as absolute, but relative to the primary colors. When the exact chromaticities of the red, green and blue primaries are defined, the normal three kinds of light-sensitive photoreceptor cells in the human eye respond most to yellow, green, and violet light. As an example, suppose that light in the range of wavelengths enters the eye. Light of these wavelengths would activate both the medium and long wavelength cones of the retina, but not equally—the long-wavelength cells will respond more, the difference in the response can be detected by the brain, and this difference is the basis of our perception of orange. Thus, the appearance of an object results from light from the object entering our eye and stimulating the different cones simultaneously. The first experiments with RGB in early color photography were made in 1861 by Maxwell himself, to reproduce the color photograph, three matching projections over a screen in a dark room were necessary
22.
Light
–
Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to light, which is visible to the human eye and is responsible for the sense of sight. Visible light is defined as having wavelengths in the range of 400–700 nanometres, or 4.00 × 10−7 to 7.00 × 10−7 m. This wavelength means a range of roughly 430–750 terahertz. The main source of light on Earth is the Sun, sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them. This process of photosynthesis provides virtually all the used by living things. Historically, another important source of light for humans has been fire, with the development of electric lights and power systems, electric lighting has effectively replaced firelight. Some species of animals generate their own light, a process called bioluminescence, for example, fireflies use light to locate mates, and vampire squids use it to hide themselves from prey. Visible light, as all types of electromagnetic radiation, is experimentally found to always move at this speed in a vacuum. In physics, the term sometimes refers to electromagnetic radiation of any wavelength. In this sense, gamma rays, X-rays, microwaves and radio waves are also light, like all types of light, visible light is emitted and absorbed in tiny packets called photons and exhibits properties of both waves and particles. This property is referred to as the wave–particle duality, the study of light, known as optics, is an important research area in modern physics. Generally, EM radiation, or EMR, is classified by wavelength into radio, microwave, infrared, the behavior of EMR depends on its wavelength. Higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths, when EMR interacts with single atoms and molecules, its behavior depends on the amount of energy per quantum it carries. There exist animals that are sensitive to various types of infrared, infrared sensing in snakes depends on a kind of natural thermal imaging, in which tiny packets of cellular water are raised in temperature by the infrared radiation. EMR in this range causes molecular vibration and heating effects, which is how these animals detect it, above the range of visible light, ultraviolet light becomes invisible to humans, mostly because it is absorbed by the cornea below 360 nanometers and the internal lens below 400. Furthermore, the rods and cones located in the retina of the eye cannot detect the very short ultraviolet wavelengths and are in fact damaged by ultraviolet. Many animals with eyes that do not require lenses are able to detect ultraviolet, by quantum photon-absorption mechanisms, various sources define visible light as narrowly as 420 to 680 to as broadly as 380 to 800 nm
23.
Complementary colors
–
Complementary colors are pairs of colors which, when combined, cancel each other out. This means that combined, they produce a grey-scale color like white or black. When placed next to other, they create the strongest contrast for those particular two colors. Due to this striking color clash, the term opposite colors is considered more appropriate than complementary colors. Opponent process theory suggests that the most contrasting color pairs are red–green, in the traditional representation, a complementary color pair is made up of a primary color and a secondary color. For example, yellow is a color, and painters can make purple by mixing of red and blue, so when yellow and purple paint are mixed. Since paints work by absorbing light, having all three primaries together results in a black or gray color, in more recent painting manuals, the more precise subtractive primary colors are magenta, cyan and yellow. Complementary colors can create some striking optical effects, the shadow of an object appears to contain some of the complementary color of the object. For example, the shadow of a red apple will appear to contain a little blue-green and this effect is often copied by painters who want to create more luminous and realistic shadows. Also, if you stare at a square of color for a period of time. Placed side by side as tiny dots, in color mixing. In the RGB model, the colors are red, green. The complementary primary–secondary combinations are red–cyan, green–magenta, and blue–yellow, if the light is not fully intense, the resulting light will be gray. In some other models, such as the HSV color space. Complementary colors lie opposite each other on any horizontal cross-section, for example, in the CIE1931 color space a color of a dominant wavelength can be mixed with an amount of the complementary wavelength to produce a neutral color. Color printing, like painting, also uses subtractive colors, but the colors are different from those used in painting. As a result, the logic applies as to colors produced by light. Color printing uses the CMYK color model, making colors by overprinting cyan, magenta, yellow, in printing the most common complementary colors are magenta–green, yellow–blue, and cyan–red
24.
White
–
White is an achromatic color, a color without hue. An incoming light to the eye that stimulates all its three types of color sensitive cone cells in nearly equal amounts results in white. White is one of the most common colors in nature, the color of sunlight, snow, milk, chalk, limestone, in many cultures white represents or signifies purity, innocence, and light, and is the symbolic opposite of black, or darkness. According to surveys in Europe and the United States, white is the color most often associated with perfection, the good, honesty, cleanliness, the beginning, the new, neutrality, and exactitude. In ancient Egypt and ancient Rome, priestesses wore white as a symbol of purity, in the Middle Ages and Renaissance a white unicorn symbolized chastity, and a white lamb sacrifice and purity, the widows of kings dressed in white rather than black as the color of mourning. It was also used in 20th century modern architecture as a symbol of modernity, simplicity. White is an important color for almost all world religions, the Pope, the head of the Roman Catholic Church, has worn white since 1566, as a symbol of purity and sacrifice. In Islam, and in the Shinto religion of Japan, it is worn by pilgrims, in Western cultures and in Japan, white is the most common color for wedding dresses, symbolizing purity and virginity. In many Asian cultures, white is also the color of mourning, the white color on television screens and computer monitors is created with the RGB color model by mixing red, green and blue light at equal intensities. The word white continues Old English hwīt, ultimately from a Common Germanic *χwītaz also reflected in OHG wîz, ON hvítr, the root is ultimately from Proto-Indo-European language *kwid-, surviving also in Sanskrit śveta to be white or bright and Slavonic světŭ light. The Icelandic word for white, hvítur, is derived from the Old Norse form of the word hvítr. Common Germanic also had the word *blankaz, borrowed into Late Latin as *blancus, the antonym of white is black. Some non-European languages have a variety of terms for white. The Inuit language has seven different words for seven different nuances of white, Japanese has six different words, depending upon brilliance or dullness, or if the color is inert or dynamic. White was one of the first colors used in art, the Lascaux Cave in France contains drawings of bulls and other animals drawn by paleolithic artists between 18,000 and 17,000 years ago. Paleolithic artists used calcite or chalk, they sometimes as a background, sometimes as a highlight, along with charcoal and red, in ancient Egypt, white was connected with the goddess Isis. The priests and priestesses of Isis dressed only in white linen, in Greece and other ancient civilizations, white was often associated with mothers milk. In Greek mythology, the chief god Zeus was nourished at the breast of the nymph Amalthea, in the Talmud, milk was one of four sacred substances, along with wine, honey, and the rose
25.
Turquoise (color)
–
Turquoise /ˈtɜːrkɔɪz/ or /ˈtɜːrkwɔɪz/ is the name of a bluish-green color, based on the gem of the same name. The word turquoise comes from the French for Turkish, as the gem was originally imported from Turkey, the first recorded use of turquoise as a color name in English was in 1573. It is, generally thought to consist of 70% blue and 30% green, the X11 color named turquoise is displayed on the right. Turquoise is an opaque, blue-to-green mineral that is a phosphate of copper and aluminium. It is rare and valuable in finer grades and has been prized as a gem, in many cultures of the Old and New Worlds, this gemstone has been esteemed for thousands of years as a holy stone, a bringer of good fortune or a talisman. The oldest evidence for this claim was found in ancient Egypt, in the ancient Persian Empire, the sky-blue gemstones were earlier worn round the neck or wrist as protection against unnatural death. If they changed color, the wearer was thought to have reason to fear the approach of doom, meanwhile, it has been discovered that turquoise can change color. The change can be caused by light, or by a chemical reaction brought about by cosmetics, Turquoise is a stone and color that is strongly associated with the domes and interiors of large mosques in Iran, Central Asia and Russia. The color Celeste is a sky bluish turquoise, light Turquoise is a lighter tone of turquoise. Turquoise blue is a close to turquoise on the color wheel. The first recorded use of blue as a color name in English was in 1900. Turquoise association of Iran is developer center of Iranian turquoise all of the world and this association started their work as the only authentic representative and exporter of precious Persian Turquoise since 1998 and now our honor is getting more and more well-thought-of in market. At right is displayed the web color medium turquoise, at right is displayed the web color dark turquoise. At right is displayed the color pearl mystic turquoise
26.
Electric blue (color)
–
The first recorded use of electric blue as a color name in English was in 1845. The color electric blue was in vogue in the 1890s, the deep tone of electric blue displayed at right is the color called bleu électrique in the Pourpre. com color list, a color list widely popular in France. This shade of electric blue reflects the kind which is only metaphorically electric, the color displayed at right titled medium electric blue matches the color of the color sample of the original called electric blue that had an immense vogue in the latter 19th century. Still today, this tone of blue is a typical contemporary electric blue fabric color that is used in manufacturing for the mass market. Dark electric blue is a cyan color that is the color called electric blue in the ISCC-NBS color list. Source of the color dark electric blue, The electric blue crayfish is a species of crayfish endemic to Florida. The electric blue gecko was first discovered by biologist William in the 1950s, the color electric blue is associated with the astrological sign of Aquarius. The color electric blue is used in the logo and site of Arch Linux, Electric Blue was the name of a 1980s soft-core pornographic television series on The Playboy Channel and its feature film spin-off. An electric blue dress features in Sir Arthur Conan Doyles The Adventure of the Copper Beeches, gerty MacDowell wears an electric blue blouse in James Joyces novel Ulysses, set in 1904, because it was expected in the Ladys Pictorial that electric blue would be worn. Electric Blue is a 1987 song released by the Australian band Icehouse, the color of the album is shown at right. Electric/Blue is a 1997 jazz fusion album by Joe Deninzon, Electric Blue is the debut solo album by Erasure frontman Andy Bell, released October 3,2005. The Electric Blue 14 are a band based in London. Strange Brew is a song by the band Cream from the 1967 album Disraeli Gears which features the lyric Shes a witch of trouble in electric blue, sound and Vision is a 1977 song released by David Bowie which features the lyric Blue, blue, electric blue. Thats the colour of my room, the Art of Storytelling, pt.2 is a 1998 ballad released by OutKast. An account of the biblical Apocalypse, the contains the lyric Look out the window. Golly, the sky is electric blue, cosmic Charlie is a song by the Grateful Dead, performed live between 1968 and 1976. It contains the lyric Rosy red and electric blue, I bought you a paddle for your paper canoe, Electric Blue is the name of a song by Nicole Scherzinger and T. I. from Scherzingers 2014 album Big Fat Lie. While retaining most of his abilities, he could now also generate electric attacks rather than his original heat-vision and this version of Superman was referred to by some comic book fans as Electric Blue Superman
27.
Blue-green
–
Blue-green is a color that is a representation of the color that is between blue and green on a typical traditional old-fashioned RYB color wheel. Blue-green belongs to the family of colors. The source of color is the List of Crayola crayon colors. Blue-green has been a Crayola crayon color since 1930, cyan, also called aqua, is the blue-green color that is between blue and green on a modern RGB color wheel. In the terminology of color theory, RGB color space has a larger color gamut than RYB color space. The first recorded use of cyan as a name in English was in 1879. At right is displayed the color turquoise, a representation of the color of the stone turquoise. The first recorded use of turquoise as a name in English was in 1573. The color turquoise is a tone of blue-green. Displayed at right is the color Ming This color was formulated in 2001 as one of the colors on the Xona. com Color List, displayed at right is the color Pacific blue. Pacific blue was formulated as a Crayola color in 1993, the color is a representation of the waters of the Pacific. Bondi blue is a color belonging to the family of blues. It is very similar to the Crayola crayon color blue-green, apple christened the color of the exterior of its original iMac G3 personal computer Bondi blue when it was introduced in 1998. The color is said to be named for the color of the water at Bondi Beach in Sydney, green-blue had been a Crayola color since 1958. It was continued as a Crayola crayon color until 1990, cerulean is a medium blue-green color that is used to represent or symbolize either the sky or the ocean. The first recorded use of cerulean as a name in English was in 1590. Teal is a medium blue-green color and it is named after the common teal, a member of the duck family, whose eyes are surrounded by the color. The color teal has a hue that is halfway between blue and green and a value that is exactly halfway between white and black
28.
Samarkand
–
Samarkand, alternatively Samarqand or Samarcand, is a city in modern-day Uzbekistan and is one of the oldest inhabited cities in Central Asia. Prospering from its location on the Silk Road between China and the Mediterranean, at times Samarkand was one of the greatest cities of Central Asia, by the time of the Achaemenid Empire of Persia, it was the capital of the Sogdian satrapy. The city was taken by Alexander the Great in 329 BC, the city was ruled by a succession of Iranian, Persian, and Turkic peoples until the Mongols under Genghis Khan conquered Samarkand in 1220. Today, Samarkand is the capital of Samarqand Region, and Uzbekistans second largest city, the city is noted for being an Islamic centre for scholarly study. In the 14th century it became the capital of the empire of Timur and is the site of his mausoleum, the Bibi-Khanym Mosque remains one of the citys most notable landmarks. The Registan was the ancient center of the city, the city has carefully preserved the traditions of ancient crafts, embroidery, gold embroidery, silk weaving, engraving on copper, ceramics, carving, and painting on wood. In 2001, UNESCO added the city to its World Heritage List as Samarkand – Crossroads of Cultures, the name probably originates in the Sogdian words asmara, stone, rock and kand, fort, town. Along with Bukhara, Samarkand is one of the oldest inhabited cities in Central Asia, archeological excavations held within the city limits as well as suburban areas unearthed evidence of human activity as early as 40,000 years old, in the late Paleolithic era. A group of Mesolithic era archeological sites were discovered at Sazagon-1, Zamichatosh, the Syob and Dargom canals, supplying the city and its suburbs with water, appeared around the 7th to 5th centuries BC. There is no evidence when Samarkand was founded. Researchers of the Institute of Archeology of Samarkand argue for the existence of the city between the 8th and 7th centuries BC, Samarkand has been one of the main centres of Sogdian civilization from its early days. By the time of the Achaemenid dynasty of Persia it had become the capital of the Sogdian satrapy, Alexander the Great conquered Samarkand in 329 BC. The city was known as Maracanda by the Greeks, written sources offer small clues as to the subsequent system of government. They tell of an Orepius who became ruler not from ancestors, while Samarkand suffered significant damage during Alexanders initial conquest, the city recovered rapidly and under the new Hellenic influence flourished. There were also major new construction techniques, oblong bricks were replaced with square ones and superior methods of masonry, Alexanders conquests introduced into Central Asia classical Greek culture, at least for a time the Greek models were followed closely by the local artisans. After the Kushan era the city declined, it did not really revive until the 5th century, Samarkand was conquered by the Sassanians around 260 AD. Under Sassanian rule, the became an essential site for Manichaeism. After the Hephtalites conquered Samarkand, they controlled it until the Göktürks, in an alliance with the Sassanid Persians, the Turks ruled over Samarkand until they were defeated by the Sassanids during the Göktürk–Persian Wars
29.
Uzbekistan
–
Uzbekistan, officially the Republic of Uzbekistan, is one of only two doubly landlocked countries in the world. Located in Central Asia, it is a unitary, constitutional, presidential republic, comprising twelve provinces, one autonomous republic and a capital city. Uzbekistan is bordered by five landlocked countries, Kazakhstan to the north, Tajikistan to the southeast, Kyrgyzstan to the northeast, Afghanistan to the south, and Turkmenistan to the southwest. Once part of the Turkic Khaganate and later Timurid Empires, the region that includes the Republic of Uzbekistan was conquered in the early 16th century by Eastern Turkic-speaking nomads. Following the breakup of the Soviet Union, it declared independence as the Republic of Uzbekistan on 31 August 1991, Uzbekistan is officially a democratic, secular, unitary, constitutional republic with a diverse cultural heritage. The countrys official language is Uzbek, a Turkic language written in the Latin alphabet and spoken natively by approximately 85% of the population, however, Uzbeks constitute 81% of the population, followed by Russians, Tajiks, Kazakhs, and others. A majority of Uzbeks are non-denominational Muslims, Uzbekistan is a member of the Commonwealth of Independent States, Organization for Security and Co-operation in Europe, UN, and the SCO. While officially a republic, non-governmental human rights organizations define Uzbekistan as an authoritarian state with limited civil rights. Uzbekistans economy relies mainly on commodity production, including cotton, gold, uranium, despite the declared objective of transition to a market economy, its government continues to maintain economic controls which imports in favour of domestic import substitution. Uzbekistan has an area of 447,400 square kilometres and it is the 56th largest country in the world by area and the 42nd by population. Among the CIS countries, it is the 4th largest by area, Uzbekistan lies between latitudes 37° and 46° N, and longitudes 56° and 74° E. It stretches 1,425 kilometres from west to east and 930 kilometres from north to south, Uzbekistan also shares a short border with Afghanistan to the south. Uzbekistan is a dry, landlocked country and it is one of two doubly landlocked countries in the world, the other being Liechtenstein. In addition, due to its location within a series of endorheic basins, less than 10% of its territory is intensively cultivated irrigated land in river valleys and oases. The rest is vast desert and mountains, the climate in the Republic of Uzbekistan is continental, with little precipitation expected annually. The average summer high temperature tends to be 40 °C, while the winter low temperature is around −23 °C. Uzbekistan has a rich and diverse natural environment, the Aral Sea used to be the fourth-largest inland sea on Earth, acting as an influencing factor in the air moisture and arid land use. Since the 1960s, the decade when the misuse of the Aral Sea water began, it has shrunk to less than 50% of its former area, reliable, or even approximate data, have not been collected, stored or provided by any organization or official agency
30.
Uranus
–
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System, Uranus is similar in composition to Neptune, and both have different bulk chemical composition from that of the larger gas giants Jupiter and Saturn. For this reason, scientists often classify Uranus and Neptune as ice giants to distinguish them from the gas giants, the interior of Uranus is mainly composed of ices and rock. Uranus is the planet whose name is derived from a figure from Greek mythology. Like the other giant planets, Uranus has a system, a magnetosphere. The Uranian system has a unique configuration among those of the planets because its axis of rotation is tilted sideways and its north and south poles, therefore, lie where most other planets have their equators. In 1986, images from Voyager 2 showed Uranus as an almost featureless planet in visible light, observations from Earth have shown seasonal change and increased weather activity as Uranus approached its equinox in 2007. Wind speeds can reach 250 metres per second, like the classical planets, Uranus is visible to the naked eye, but it was never recognised as a planet by ancient observers because of its dimness and slow orbit. Uranus had been observed on many occasions before its recognition as a planet, possibly the earliest known observation was by Hipparchos, who in 128 BCE might have recorded it as a star for his star catalogue that was later incorporated into Ptolemys Almagest. The earliest definite sighting was in 1690 when John Flamsteed observed it at least six times, the French astronomer Pierre Lemonnier observed Uranus at least twelve times between 1750 and 1769, including on four consecutive nights. Sir William Herschel observed Uranus on March 13,1781 from the garden of his house at 19 New King Street in Bath, Somerset, England, Herschel engaged in a series of observations on the parallax of the fixed stars, using a telescope of his own design. Herschel recorded in his journal, In the quartile near ζ Tauri, either Nebulous star or perhaps a comet. On March 17 he noted, I looked for the Comet or Nebulous Star and found that it is a Comet, the sequel has shown that my surmises were well-founded, this proving to be the Comet we have lately observed. Herschel notified the Astronomer Royal, Nevil Maskelyne, of his discovery and received this flummoxed reply from him on April 23,1781, I dont know what to call it. It is as likely to be a planet moving in an orbit nearly circular to the sun as a Comet moving in a very eccentric ellipsis. I have not yet seen any coma or tail to it, although Herschel continued to describe his new object as a comet, other astronomers had already begun to suspect otherwise. Finnish-Swedish astronomer Anders Johan Lexell, working in Russia, was the first to compute the orbit of the new object and its nearly circular orbit led him to a conclusion that it was a planet rather than a comet. Berlin astronomer Johann Elert Bode described Herschels discovery as a star that can be deemed a hitherto unknown planet-like object circulating beyond the orbit of Saturn
31.
Voyager 2
–
Voyager 2 is a space probe launched by NASA on August 20,1977, to study the outer planets. Part of the Voyager program, it was launched 16 days before its twin, Voyager 1, on a trajectory that took longer to reach Jupiter and Saturn but enabled further encounters with Uranus and it is the only spacecraft to have visited either of the ice giants. Voyager 2 is now in its mission to study the outer reaches of the Solar System and has been operating for 39 years,7 months and 17 days. It remains in contact through the Deep Space Network, at a distance of 114 AU from the Sun as of April 5th,2017, Voyager 2 is one of the most distant human-made objects, along with Voyager 1, New Horizons, Pioneer 10 and Pioneer 11. The probe was moving at a velocity of 15.4 km/s relative to the Sun as of December 2014 and is traveling through the heliosheath, upon reaching interstellar space, Voyager 2 is expected to provide the first direct measurements of the density and temperature of the interstellar plasma. The spacecraft would be designed with redundant systems to ensure survival through the entire tour, by 1972 the mission was scaled back and replaced with two Mariner-derived spacecraft, the Mariner Jupiter-Saturn probes. To keep apparent lifetime program costs low, the mission would include only flybys of Jupiter and Saturn, as the program progressed, the name was changed to Voyager. The primary mission of Voyager 1 was to explore Jupiter, Saturn, Voyager 2 was also to explore Jupiter and Saturn, but on a trajectory that would have option of continuing on to Uranus and Neptune, or being redirected to Titan as a backup for Voyager 1. Upon successful completion of Voyager 1s objectives, Voyager 2 would get an extension to send the probe on towards Uranus. Collectively these instruments are part of the Attitude and Articulation Control Subsystem along with redundant units of most instruments and 8 backup thrusters, the spacecraft also included 11 scientific instruments to study celestial objects as it traveled through space. Built with the intent for eventual interstellar travel, Voyager 2 included a large,3.7 m parabolic, when the spacecraft is unable to communicate with Earth, the Digital Tape Recorder can record about 64 kilobytes of data for transmission at another time. The spacecraft was built with 3 Multihundred-Watt radioisotope thermoelectric generators, each RTG includes 24 pressed plutonium oxide spheres and provides enough heat to generate approximately 157 watts of power at launch. Collectively, the RTGs supply the spacecraft with 470 watts at launch, for more details on the Voyager space probes identical instrument packages, see the separate article on the overall Voyager Program. The Voyager 2 probe was launched on August 20,1977, by NASA from Space Launch Complex 41 at Cape Canaveral, Florida, two weeks later, the twin Voyager 1 probe would be launched on September 5,1977. However, Voyager 1 would reach both Jupiter and Saturn sooner, as Voyager 2 had been launched into a longer, more circular trajectory, Voyager 2s closest approach to Jupiter occurred on July 9,1979. It came within 570,000 km of the cloud tops. It discovered a few rings around Jupiter, as well as volcanic activity on the moon Io, the Great Red Spot was revealed as a complex storm moving in a counterclockwise direction. An array of other storms and eddies were found throughout the banded clouds
32.
Ancient Greek
–
Ancient Greek includes the forms of Greek used in ancient Greece and the ancient world from around the 9th century BC to the 6th century AD. It is often divided into the Archaic period, Classical period. It is antedated in the second millennium BC by Mycenaean Greek, the language of the Hellenistic phase is known as Koine. Koine is regarded as a historical stage of its own, although in its earliest form it closely resembled Attic Greek. Prior to the Koine period, Greek of the classic and earlier periods included several regional dialects, Ancient Greek was the language of Homer and of fifth-century Athenian historians, playwrights, and philosophers. It has contributed many words to English vocabulary and has been a subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Epic and Classical phases of the language, Ancient Greek was a pluricentric language, divided into many dialects. The main dialect groups are Attic and Ionic, Aeolic, Arcadocypriot, some dialects are found in standardized literary forms used in literature, while others are attested only in inscriptions. There are also several historical forms, homeric Greek is a literary form of Archaic Greek used in the epic poems, the Iliad and Odyssey, and in later poems by other authors. Homeric Greek had significant differences in grammar and pronunciation from Classical Attic, the origins, early form and development of the Hellenic language family are not well understood because of a lack of contemporaneous evidence. Several theories exist about what Hellenic dialect groups may have existed between the divergence of early Greek-like speech from the common Proto-Indo-European language and the Classical period and they have the same general outline, but differ in some of the detail. The invasion would not be Dorian unless the invaders had some relationship to the historical Dorians. The invasion is known to have displaced population to the later Attic-Ionic regions, the Greeks of this period believed there were three major divisions of all Greek people—Dorians, Aeolians, and Ionians, each with their own defining and distinctive dialects. Often non-west is called East Greek, Arcadocypriot apparently descended more closely from the Mycenaean Greek of the Bronze Age. Boeotian had come under a strong Northwest Greek influence, and can in some respects be considered a transitional dialect, thessalian likewise had come under Northwest Greek influence, though to a lesser degree. Most of the dialect sub-groups listed above had further subdivisions, generally equivalent to a city-state and its surrounding territory, Doric notably had several intermediate divisions as well, into Island Doric, Southern Peloponnesus Doric, and Northern Peloponnesus Doric. The Lesbian dialect was Aeolic Greek and this dialect slowly replaced most of the older dialects, although Doric dialect has survived in the Tsakonian language, which is spoken in the region of modern Sparta. Doric has also passed down its aorist terminations into most verbs of Demotic Greek, by about the 6th century AD, the Koine had slowly metamorphosized into Medieval Greek
33.
Dye
–
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber. Both dyes and pigments are colored because they absorb some wavelengths of light more than others, in contrast to dyes, pigments are insoluble and have no affinity for the substrate. Some dyes can be precipitated with a salt to produce a lake pigment. The majority of natural dyes are from plant sources, roots, berries, bark, leaves, and wood, fungi, textile dyeing dates back to the Neolithic period. Throughout history, people have dyed their textiles using common, locally available materials, scarce dyestuffs that produced brilliant and permanent colors such as the natural invertebrate dyes Tyrian purple and crimson kermes were highly prized luxury items in the ancient and medieval world. Plant-based dyes such as woad, indigo, saffron, and madder were raised commercially and were important trade goods in the economies of Asia, across Asia and Africa, patterned fabrics were produced using resist dyeing techniques to control the absorption of color in piece-dyed cloth. Dyes from the New World such as cochineal and logwood were brought to Europe by the Spanish treasure fleets, dyed flax fibers have been found in the Republic of Georgia in a prehistoric cave dated to 36,000 BP. Archaeological evidence shows that, particularly in India and Phoenicia, dyeing has been carried out for over 5,000 years. The dyes were obtained from animal, vegetable or mineral origin, by far the greatest source of dyes has been from the plant kingdom, notably roots, berries, bark, leaves and wood, but only a few have ever been used on a commercial scale. The discovery of synthetic dyes late in the 19th century ended the large-scale market for natural dyes. These dyes are made from synthetic resources such as petroleum by-products, the first human-made organic aniline dye, mauveine, was discovered serendipitously by William Henry Perkin in 1856, the result of a failed attempt at the total synthesis of quinine. Other aniline dyes followed, such as fuchsine, safranine, many thousands of synthetic dyes have since been prepared. These may be natural or synthetic, other than pigmentation, they have a range of applications including organic dye lasers, optical media and camera sensors. This is the basic classification Dyes are classified according to their solubility, acid dyes are water-soluble anionic dyes that are applied to fibers such as silk, wool, nylon and modified acrylic fibers using neutral to acid dye baths. Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and cationic groups in the fiber, acid dyes are not substantive to cellulosic fibers. Most synthetic food colors fall in this category, basic dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers, but find some use for wool and silk. Usually acetic acid is added to the dye bath to help the uptake of the dye onto the fiber, basic dyes are also used in the coloration of paper
34.
Centaurea cyanus
–
Centaurea cyanus, commonly known as cornflower, is an annual flowering plant in the family Asteraceae, native to Europe. In the past it often grew as a weed in cornfields, in reaction to this, the conservation charity Plantlife named it as one of 101 species it would actively work to bring Back from the Brink. Cornflower is a plant growing to 16-35 inches tall, with grey-green branched stems. The leaves are lanceolate, 1–4 cm long, the flowers are most commonly an intense blue colour, produced in flowerheads 1. 5–3 cm diameter, with a ring of a few large, spreading ray florets surrounding a central cluster of disc florets. The blue pigment is protocyanin, which in roses is red, Centaurea cyanus is native to temperate Europe, but is widely naturalized outside its native range. It has been present in the British Isles as an archaeophyte since the Iron Age, in Ireland, in Co. Clare Centaurea cyanus is recorded in arable fields as very rare and almost extinct. While in the north-east of Ireland it was abundant before 1930s, the common names bachelors button, bluebottle, boutonniere flower, hurtsickle or cyani flower are also used. It may also be referred to as basketflower, though the term refers to the Plectocephalus group of Centaurea. Cornflower is also used for chicory, and a few other Centaurea species and it is grown as an ornamental plant in gardens, where several cultivars have been selected with varying pastel colours, including pink and purple. Cornflower is also grown for the industry in Canada for use by florists. The most common variety for this use is a doubled blue variety such as Blue Boy or Blue Diadem. White, pink, lavender and black are used but less commonly. A relative, Centaurea montana, is a plant which is also cultivated as a garden plant. Soil pH requirements, neutral to mildly alkaline, the cornflower is considered a beneficial weed, and its edible flower can be used for culinary decoration, for example to add colour to salads. In herbalism, a decoction of cornflower is effective in treating conjunctivitis, cornflowers have been used and prized historically for their blue pigment. Cornflowers are often used as an ingredient in some tea blends and herbal teas, in folklore, cornflowers were worn by young men in love, if the flower faded too quickly, it was taken as a sign that the mans love was not returned. The blue cornflower has been the national flower of Estonia since 1968, the blue cornflower was one of the national symbols of Germany. The flower thus became identified with Prussia, not least because it was the color as the Prussian military uniform
35.
Distinction of blue and green in various languages
–
Many languages do not distinguish between what in English are described as blue and green. They instead use a cover term spanning both, when the issue is discussed in linguistics, this cover term is sometimes called grue in English. For example, blue and green might be distinguished, but a term might be used for both if the color is dark. Furthermore, green might be associated with yellow, and blue with black or gray, in their account of the development of color terms the first terms to emerge are those for white/black, red and green/yellow. The word for blue in Amazigh language is Azerwal, in some dialects of Amazigh, like Shelha, the word Azegzaw is used for both green and blue. The color of the sky is sometimes referred to as the green in Classical Arabic poetry, in Arabic the word for blue is generally azraq. The Arabic word for green is akhḍar, in Moroccan Arabic, the word for light blue is šíbi, whereas zraq stands for blue and khḍar for green. The word zrag is used to describe the color of a suffocated person, the ancient Egyptian word wadjet covers the range of blue, blue-green, and green. On the one hand, it was the name of a goddess, the patroness of Lower Egypt, represented as a cobra called Wadjet, on the other hand, wedjet was the word used for Egyptian blue in faience ceramics. In Hebrew, the word כחול means blue, while ירוק means green and has the root, י־ר־ק. However, in classical Hebrew, ירוק can mean green and yellow, giving rise to such expressions as ירוק כרתי, leek green. Like Russian and Italian, Hebrew has a name for light blue —the color of the sky. This color has special significance in Judaism and Jewish culture. There are separate words for green and blue in Latvian, both zils and zaļš stem from the same Proto-Indo-European word for yellow. Several other words in Latvian have been derived from these colors, the now archaic word mēļš was used to describe both dark blue and black. For instance, blueberries and blackberries are called mellenes, in Lithuanian žalias is green, mėlynas is blue and žilas is grey, grizzled. Bulgarian, a South Slavic language, makes a distinction between blue, green, and black. In the Polish language, blue and green are treated as separate colors, the word for sky blue or azure—błękitny—might be considered either a basic color or a shade of blue by different speakers
Color coordinates
