1.
IndiGo
–
Indigo is a deep and rich color close to the color wheel blue, as well as to some variants of ultramarine. The color indigo is named after the indigo dye derived from the plant Indigofera tinctoria, the first known recorded use of indigo as a color name in English was in 1289. Species of Indigofera were cultivated in Peru, India, East Asia, the earliest direct evidence for the use of indigo dates to around 4000 BCE and comes from Huaca Prieta, in contemporary Peru. Pliny mentions India as the source of the dye, imported in small quantities via the Silk Road, the Greek term for the dye was Ἰνδικὸν φάρμακον, which, adopted to Latin as indicum and via Portuguese gave rise to the modern word indigo. El Salvador has lately been the biggest producer of indigo, Indigo was actually a plant that got its name because it came from the Indus Valley, discovered some 5,000 years ago, where it was called nila, meaning dark blue. And by the 7th Century BC, people starting using the plant as a dye — the Mesopotamians were even carving out recipes for making indigo dye onto clay tablets for record-keeping. By 1289, knowledge of the dye made its way to Europe, but it wasn’t until 1640 when demand started to pick up for indigo. Spanish explorers discovered an American species of Indigo and began to cultivate the product in Guatemala, the English and French subsequently began to encourage indigo cultivation in their colonies in the West Indies. Indigo dye could be made from two different types of plants — the indigo plant, which produced the best results, the British were producing indigo with woad, a plant that yielded a lesser quality dye, but a plant they could grow. They even tried to hold their monopoly on indigo dye by managing to ban the indigo plant for years, but eventually the British began to focus on tea and other crops — and meanwhile, the French started to get their fair share of the market. The French had gone to war with Britain, so the British could hardly rely on the French for this precious blue dye, consequently, the British had to turn to their colonies in America. It was Eliza Lucas from South Carolina who figured out how to grow the indigo plant, the same indigo dye is contained in the woad plant, Isatis tinctoria, for a long time the main source of blue dye in Europe. Woad was replaced by true indigo as trade routes opened up, the Early Modern English word indigo referred to the dye, and not to the color itself, and indigo is not traditionally part of the basic color-naming system. Modern sources place indigo in the spectrum between 420 and 450 nanometers, which lies on the side of color wheel blue. However, the correspondence of this definition with colors of actual indigo dyes is disputed, isaac Newton introduced indigo as one of the seven base colors of his work. In a pivotal experiment in the history of optics, the young Newton shone a narrow beam of sunlight through a prism to produce a band of colors on the wall. He linked the seven prismatic colors to the seven notes of a major scale, as shown in his color wheel, with orange. Indigo is therefore counted as one of the colors of the rainbow
IndiGo
–
A piece of indigo plant dye from India, about 2.5 inches (6 cm) square
IndiGo
–
Extract of natural indigo applied to paper
IndiGo
–
Newton's observation of prismatic colors. Comparing this to a color image of the visible light spectrum will show that "Indigo" corresponds to
blue, while "Blue" corresponds to
cyan.
IndiGo
–
Indigo is created in potholes carved in pumice "tufgrond" in Karoland,
Sumatra
2.
India
–
India, officially the Republic of India, is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and it is bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast. It shares land borders with Pakistan to the west, China, Nepal, and Bhutan to the northeast, in the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives. Indias Andaman and Nicobar Islands share a border with Thailand. The Indian subcontinent was home to the urban Indus Valley Civilisation of the 3rd millennium BCE, in the following millennium, the oldest scriptures associated with Hinduism began to be composed. Social stratification, based on caste, emerged in the first millennium BCE, early political consolidations took place under the Maurya and Gupta empires, the later peninsular Middle Kingdoms influenced cultures as far as southeast Asia. In the medieval era, Judaism, Zoroastrianism, Christianity, and Islam arrived, much of the north fell to the Delhi sultanate, the south was united under the Vijayanagara Empire. The economy expanded in the 17th century in the Mughal empire, in the mid-18th century, the subcontinent came under British East India Company rule, and in the mid-19th under British crown rule. A nationalist movement emerged in the late 19th century, which later, under Mahatma Gandhi, was noted for nonviolent resistance, in 2015, the Indian economy was the worlds seventh largest by nominal GDP and third largest by purchasing power parity. Following market-based economic reforms in 1991, India became one of the major economies and is considered a newly industrialised country. However, it continues to face the challenges of poverty, corruption, malnutrition, a nuclear weapons state and regional power, it has the third largest standing army in the world and ranks sixth in military expenditure among nations. India is a constitutional republic governed under a parliamentary system. It is a pluralistic, multilingual and multi-ethnic society and is home to a diversity of wildlife in a variety of protected habitats. The name India is derived from Indus, which originates from the Old Persian word Hindu, the latter term stems from the Sanskrit word Sindhu, which was the historical local appellation for the Indus River. The ancient Greeks referred to the Indians as Indoi, which translates as The people of the Indus, the geographical term Bharat, which is recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations. Scholars believe it to be named after the Vedic tribe of Bharatas in the second millennium B. C. E and it is also traditionally associated with the rule of the legendary emperor Bharata. Gaṇarājya is the Sanskrit/Hindi term for republic dating back to the ancient times, hindustan is a Persian name for India dating back to the 3rd century B. C. E. It was introduced into India by the Mughals and widely used since then and its meaning varied, referring to a region that encompassed northern India and Pakistan or India in its entirety
India
–
Flag
India
–
The granite
tower of
Brihadeeswarar Temple in
Thanjavur was completed in 1010 CE by
Raja Raja Chola I.
India
–
Writing the will and testament of the Mughal king court in Persian, 1590–1595
3.
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
Wavelength
–
Wavelength is decreased in a medium with slower propagation.
Wavelength
–
Wavelength of a
sine wave, λ, can be measured between any two points with the same
phase, such as between crests, or troughs, or corresponding
zero crossings as shown.
Wavelength
–
Various local wavelengths on a crest-to-crest basis in an ocean wave approaching shore
Wavelength
–
A wave on a line of atoms can be interpreted according to a variety of wavelengths.
4.
SRGB color space
–
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
SRGB color space
5.
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
Red
–
Pure, or solid red, the color of most ripe
strawberries.
Red
–
Red
Red
–
Scarlet is one quarter of the way between the colors red and orange. It is the color worn by a
cardinal of the
Roman Catholic Church..
Red
–
The
cardinal takes its name from the color worn by Roman Catholic
cardinals.
6.
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
Green
–
The word green has the same Germanic root as the words for grass and grow.
Green
–
Green
Green
–
Emerald green. The
Gachala Emerald from the
National Museum of Natural History, Washington.
Green
–
Jade. A jade dragon from the
Han Dynasty, China. Jade can be many different shades of green.
7.
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
Blue
–
Sky blue or pale
azure, mid-way on the RBG colour wheel between blue and cyan.
Blue
–
Blue
Blue
–
Extract of natural
indigo, the most popular blue dye before the invention of synthetic dyes. It was the colour of the first
blue jeans.
Blue
–
A block of
lapis lazuli, originally used to make ultramarine.
8.
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
CMYK color model
–
A color photograph of the
Teton Range.
CMYK color model
–
Color printing typically uses ink of four colors: cyan, magenta, yellow, and key (black).
CMYK color model
–
The image above, separated for printing with process cyan, magenta, and yellow inks.
CMYK color model
–
The same image, this time separated with maximum black, to minimize ink use.
9.
Cyan
–
It is evoked by light with a predominant wavelength of between 490–520 nm, between the wavelengths of blue and green. In the subtractive color system, or CMYK, which can be overlaid to produce all colors in paint and color printing, cyan is one of the colors, along with magenta, yellow. In the additive color system, or RGB color model, used to all the colors on a computer or television display, cyan is made by mixing equal amounts of green. Cyan is the complement of red, it can be made by the removal of red from white light, mixing red light and cyan light at the right intensity will make white light. The web color cyan is synonymous with aqua, other colors in the cyan color range are teal, turquoise, electric blue, aquamarine, and others described as blue-green. Its name is derived from the Ancient Greek κύανος, transliterated kyanos, meaning blue, dark blue enamel. It was formerly known as blue or cyan-blue, and its first recorded use as a color name in English was in 1879. Further origins of the name can be traced back to a dye produced from the cornflower. In most languages, cyan is not a color term. Reasons for why cyan is not linguistically acknowledged as a color term can be found in the frequent lack of distinction between blue and green in many languages. The web color cyan shown at right is a color in the RGB color model. In X11 colors, this color is called both cyan and aqua, in the HTML color list, this same color is called aqua. The web colors are more vivid than the used in the CMYK color system. To reproduce the web color cyan in inks, it is necessary to add some white ink to the printers cyan below, so when it is reproduced in printing, it is not a primary subtractive color. It is called aqua because it is a commonly associated with water. Cyan is also one of the inks used in four-color printing, along with magenta, yellow, and black. While both the secondary and the subtractive primary are called cyan, they can be substantially different from one another. Cyan printing ink can be saturated or less saturated than the RGB secondary cyan, depending on what RGB color space
Cyan
–
In the
RGB color model, used to make colors on computer and TV displays, cyan is created by the combination of green and blue light.
Cyan
–
Cyan
Cyan
–
Color printers today use magenta, cyan, and yellow ink to produce the full range of colors.
Cyan
–
Cyan is the color of shallow water over a sandy beach. The water absorbs the color red from the sunlight, leaving a greenish-blue color.
10.
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
Magenta
–
In the
RGB color model, used to make colors on computer and television displays, magenta is created by the combination of equal amounts of blue and red light.
Magenta
–
Magenta
Magenta
–
The flower of
Fuchsia plant was the original inspiration for the dye, which was later renamed magenta dye.
Magenta
–
Magenta took its name in 1860 from this
aniline dye that was originally called "
fuchsine ", after the fuchsia flower.
11.
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
Yellow
–
Yellow is the color of
gold,
butter, and ripe
lemons.
Yellow
–
Yellow
Yellow
–
Image of a horse colored with
yellow ochre. from
Lascaux cave.
Yellow
–
Paintings in the Tomb of Nakht in
ancient Egypt (15th century BC).
12.
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
Black
–
Outer space seen from Mars (Image taken by
NASA 's
MER Spirit rover)
Black
–
Neolithic paintings of bulls in the
Lascaux Cave, more than 17,000 years old
Black
–
Statue of Anubis, guardian of the underworld, from the tomb of
Tutankhamun.
Black
–
Greek
Black-figure pottery.
Ajax and
Achilles playing a game, about 540-530 BC. (Vatican Museums).
13.
HSV color space
–
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
HSV color space
–
Fig. 13a. Color photograph
HSV color space
HSV color space
–
b. CIELAB L *
HSV color space
–
c. Rec. 601 luma Y ′
14.
Saturation (color theory)
–
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
Saturation (color theory)
–
Original image, with relatively muted colors
Saturation (color theory)
–
L*C*h (
CIELAB) chroma increased 50%
Saturation (color theory)
–
HSL saturation increased 50%; notice that changing HSL saturation also affects the perceived lightness of a color
Saturation (color theory)
–
CIELAB lightness preserved, with a * and b * stripped, to make a
grayscale image
15.
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
Brightness
–
Decreasing brightness with depth (underwater photo as example)
16.
Blue (RGB)
–
Varieties of the color blue may differ in hue, chroma, or lightness, or in two or three of these qualities. Variations in value are also called tints and shades, a tint being a blue or other hue mixed with white, a large selection of these various colors is shown below. In this section, the term tint is used in its sense as used in color theory. Baby blue is known as one of the pastel colors, with a hue code of 199, this color is a tone of azure. The first recorded use of blue as a color name in English was in 1892. The web color blue is displayed in the color box at right. Variations of this color are known as sky blue, baby blue, within the X11 color system, with a hue code of 194, this color is closer to cyan than to blue. The first recorded use of blue as a color term in English is in the year 1915. Shown in the right is the color periwinkle, or periwinkle blue, another name for this color is lavender blue. The color is a mixture of white and blue and it is named after the Periwinkle flower and is also commonly referred to as a tone of light blue. The web color blue is shown on the right. The first recorded use of blue as a color name in English was in 1774. Displayed at right is the color morning blue and it is a representation of the color of the morning sky. The year the first recorded use of morning blue as a name in English is unknown. Source of color, ISCC-NBS Dictionary of Color Names --Color Sample of Morning Blue The color defined as blue in the RGB color model and this color is the brightest possible blue that can be reproduced on a computer screen, and is the color named blue in X11. It is one of the three colors used on the RGB color space, along with red and green. This color is called color wheel blue. It is at precisely 240 degrees on the HSV color wheel and it is a spectral color which lies at, or near, the short-wave end of the traditional blue and possibly was classified as indigo by Newton
Blue (RGB)
–
Red, green, and blue
lights, representing the three basic
additive primary colors of the RGB color system, red, green, and blue
Blue (RGB)
–
Blue
Blue (RGB)
–
Blueberries
Blue (RGB)
–
German police officer
17.
RGB color space
–
An RGB color space is any additive color space based on the RGB color model. The complete specification of an RGB color space requires a white point chromaticity. As of 2007, sRGB is by far the most commonly used RGB color space, RGB is an abbreviation for red–green–blue. An RGB color space can be understood by thinking of it as all colors that can be made from three colored lights for red, green, and blue. Imagine, for example, shining three lights together onto a wall in a dark room, one red light, one green light. If only the red light is on, the wall will be red, if only the green light is on, the wall will look green. If the red and green lights are on together, the wall will look yellow, dim the red light and the wall will become more of a yellow-green. Dim the green light instead, and the wall will become more orange, bringing up the blue light a bit will cause the orange to become less saturated and more whitish. In all, each setting of the three dimmers will produce a different result, either in color or in brightness or both, the set of all possible results is the gamut defined by those particular color lamps. An LCD display can be thought of as a grid of thousands of red, green. The gamut of the display will depend on the three used for the red, green, and blue lights. A wide-gamut display will have very saturated, pure light colors, RGB is a convenient color model for computer graphics because the human visual system works in a way that is similar – though not quite identical – to an RGB color space. The most commonly used RGB color spaces are sRGB and Adobe RGB, Adobe has recently developed another color space called Adobe Wide Gamut RGB, which is even larger, in detriment to gamut density. As of 2007, sRGB is by far the most commonly used RGB color space, particularly in consumer digital cameras, HD video cameras. HDTVs use a space, commonly called Rec. The sRGB space is considered adequate for most consumer applications, having all devices use the same color space is convenient in that an image does not need to be converted from one color space to another before being displayed. However, sRGBs limited gamut leaves out many highly saturated colors that can be produced by printers or in film, the wider gamut Adobe RGB is being built into more medium-grade digital cameras, and is favored by many professional graphic artists for its larger gamut. RGB spaces are generally specified by defining three primary colors and a white point, in the table below the three primary colors and white points for various RGB spaces are given
RGB color space
–
RGB-Cube
18.
Ultramarine
–
Ultramarine is a deep blue color and a pigment which was originally made by grinding lapis lazuli into a powder. The name comes from the Latin ultramarinus, literally beyond the sea, Ultramarine was the finest and most expensive blue used by Renaissance painters. It was often used for the robes of the Virgin Mary and it remained an extremely expensive pigment until a synthetic ultramarine was invented in 1826. The pigment consists primarily of a mineral containing small amounts of polysulfides. It occurs in nature as a component of lapis lazuli containing a blue cubic mineral called lazurite. The pigment color code is P, the major component of lazurite is a complex sulfur-containing sodium-silicate, which makes ultramarine the most complex of all mineral pigments. Some chloride is present in the crystal lattice as well. The blue color of the pigment is due to the S−3 radical anion, the preparation is typically made in steps. The first part of the takes place at 700 to 750 °C in a closed furnace, so that sulphur, carbon. This yields a yellow-green product sometimes used as a pigment, in the second step air or sulphur dioxide at 350 to 450 °C is used to oxidise sulphide sulphur in the intermediate product to S2 and Sn chromophore molecules, resulting in the blue pigment. The mixture is heated in a kiln, sometimes in brick-sized amounts, the resultant solids are then ground and washed as per any other insoluble pigment manufacturing process. The chemical reaction produces large amounts of sulfur dioxide, meaning that flue-gas desulfurization is an part of its manufacture to comply with pollution regulations. Large chimneys were used to disperse sulfur dioxide produced in the process, resulting in ultramarine tinting the surrounding ground surfaces, Ultramarine poor in silica is obtained by fusing a mixture of soft clay, sodium sulfate, charcoal, sodium carbonate and sulfur. The product is at first white, but soon turns green green ultramarine when it is mixed with sulfur, the sulfur burns, and a fine blue pigment is obtained. Ultramarine rich in silica is obtained by heating a mixture of pure clay, very fine white sand, sulfur. A blue product is obtained at once, but a red tinge often results, the different ultramarines—green, blue, red and violet—are finely ground and washed with water. Its color is unaffected by light nor by contact with oil or lime as used in painting, hydrochloric acid immediately bleaches it with liberation of hydrogen sulfide. Even a small addition of oxide to the reddish varieties especially causes a considerable diminution in the intensity of the color
Ultramarine
–
Synthetic ultramarine
pigment
Ultramarine
–
Lapis lazuli specimen (rough), Afghanistan
Ultramarine
–
Natural ultramarine
Ultramarine
–
Synthetic ultramarine violet
19.
Visible spectrum
–
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm, in terms of frequency, this corresponds to a band in the vicinity of 430–770 THz. The spectrum does not, however, contain all the colors that the human eyes, unsaturated colors such as pink, or purple variations such as magenta, are absent, for example, because they can be made only by a mix of multiple wavelengths. Colors containing only one wavelength are called pure colors or spectral colors. Visible wavelengths pass through the window, the region of the electromagnetic spectrum that allows wavelengths to pass largely unattenuated through the Earths atmosphere. An example of this phenomenon is that clean air scatters blue light more than red wavelengths, the optical window is also referred to as the visible window because it overlaps the human visible response spectrum. The near infrared window lies just out of the vision, as well as the Medium Wavelength IR window. In the 13th century, Roger Bacon theorized that rainbows were produced by a process to the passage of light through glass or crystal. In the 17th century, Isaac Newton discovered that prisms could disassemble and reassemble white light and he was the first to use the word spectrum in this sense in print in 1671 in describing his experiments in optics. The result is red light is bent less sharply than violet as it passes through the prism. Newton divided the spectrum into seven named colors, red, orange, yellow, green, blue, indigo, the human eye is relatively insensitive to indigos frequencies, and some people who have otherwise-good vision cannot distinguish indigo from blue and violet. For this reason, some commentators, including Isaac Asimov, have suggested that indigo should not be regarded as a color in its own right. However, the evidence indicates that what Newton meant by indigo, comparing Newtons observation of prismatic colors to a color image of the visible light spectrum shows that indigo corresponds to what is today called blue, whereas blue corresponds to cyan. In the 18th century, Goethe wrote about optical spectra in his Theory of Colours, Goethe used the word spectrum to designate a ghostly optical afterimage, as did Schopenhauer in On Vision and Colors. Goethe argued that the spectrum was a compound phenomenon. Where Newton narrowed the beam of light to isolate the phenomenon, Goethe observed that a wider aperture produces not a spectrum but rather reddish-yellow, the spectrum appears only when these edges are close enough to overlap. Young was the first to measure the wavelengths of different colors of light, the connection between the visible spectrum and color vision was explored by Thomas Young and Hermann von Helmholtz in the early 19th century
Visible spectrum
–
White
light is
dispersed by a
prism into the colors of the visible spectrum.
Visible spectrum
–
Newton's observation of prismatic colors (
David Brewster 1855)
20.
Rainbow
–
A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It takes the form of a multicoloured arc, Rainbows caused by sunlight always appear in the section of sky directly opposite the sun. However, the observer sees only an arc formed by illuminated droplets above the ground. In a primary rainbow, the arc shows red on the outer part and this rainbow is caused by light being refracted when entering a droplet of water, then reflected inside on the back of the droplet and refracted again when leaving it. In a double rainbow, an arc is seen outside the primary arc. A rainbow is not located at a distance from the observer. Thus, a rainbow is not an object and cannot be physically approached, indeed, it is impossible for an observer to see a rainbow from water droplets at any angle other than the customary one of 42 degrees from the direction opposite the light source. Even if an observer sees another observer who seems under or at the end of a rainbow, Rainbows span a continuous spectrum of colours. Rainbows can be caused by many forms of airborne water and these include not only rain, but also mist, spray, and airborne dew. Rainbows can be observed there are water drops in the air. Because of this, rainbows are seen in the western sky during the morning. The most spectacular rainbow displays happen when half the sky is dark with raining clouds. The result is a rainbow that contrasts with the darkened background. During such good visibility conditions, the larger but fainter secondary rainbow is often visible and it appears about 10° outside of the primary rainbow, with inverse order of colours. The rainbow effect is commonly seen near waterfalls or fountains. In addition, the effect can be created by dispersing water droplets into the air during a sunny day. Rarely, a moonbow, lunar rainbow or nighttime rainbow, can be seen on strongly moonlit nights, as human visual perception for colour is poor in low light, moonbows are often perceived to be white. It is difficult to photograph the complete semicircle of a rainbow in one frame, for a 35 mm camera, a wide-angle lens with a focal length of 19 mm or less would be required
Rainbow
–
Double rainbow and supernumerary rainbows on the inside of the primary arc. The shadow of the photographer's head on the bottom marks the centre of the rainbow circle (
antisolar point).
Rainbow
–
Image of the end of a rainbow at
Jasper National Park
Rainbow
–
Rainbows can form in mist, such as that of a waterfall.
Rainbow
–
Rainbow with a faint reflected rainbow in the lake
21.
Violet (color)
–
Violet is the color of amethyst, lavender and beautyberries. It takes its name from the violet flower, Violet is the color at the end of the visible spectrum of light between blue and the invisible ultraviolet. Violet color has a predominant light wavelength of roughly 380-450 nanometers, light with a shorter wavelength than violet but longer than X-rays and gamma rays is called ultraviolet. In the color wheel used by painters, it is located between blue and purple. This is not true violet, since it is composed of multiple longer wavelengths rather than a wavelength shorter than that of blue light. Violet and purple look very similar, but violet is a color, with its own set of wavelengths on the spectrum of visible light, while purple is a composite color, made by combining blue. In history, violet and purple have long associated with royalty and majesty. The emperors of Rome wore purple togas, as did the Byzantine emperors, during the Middle Ages violet was worn by bishops and university professors and was often used in art as the color of the robes of the Virgin Mary. According to surveys in Europe and the United States, violet is the people most often associate with extravagance and individualism, the unconventional, the artificial. In Chinese painting, the color represents the harmony of the universe because it is a combination of red. In Hinduism and Buddhism violet is associated with the Crown Chakra, from the Middle English and old French violette, and from the Latin viola, the names of the violet flower. The first recorded use of violet as a name in English was in 1370. Violet can also refer to the first violas which were painted a similar color. In the traditional color used by painters, violet and purple are both placed between red and blue. Purple occupies the space closer to red, between crimson and violet, Violet is closer to blue, and usually less intense and bright than purple. The range of purples is created by combining blue and red light of any intensities, Violet is one of the oldest colors used by man. It has also found in the cave of Altamira and Lascaux. It was sometimes used an alternative to black charcoal, sticks of manganese, used for drawing, have been found at sites occupied by Neanderthal man in France and Israel
Violet (color)
–
The
violet flower
Violet (color)
–
Violet
Violet (color)
–
Amethyst mineral
Violet (color)
–
Lilac flowers
22.
Electromagnetic spectrum
–
The electromagnetic spectrum is the collective term for all known frequencies and their linked wavelengths of the known photons. The electromagnetic spectrum of an object has a different meaning, and is instead the characteristic distribution of radiation emitted or absorbed by that particular object. Visible light lies toward the end, with wavelengths from 400 to 700 nanometres. The limit for long wavelengths is the size of the universe itself, until the middle of the 20th century it was believed by most physicists that this spectrum was infinite and continuous. Nearly all types of radiation can be used for spectroscopy, to study. Other technological uses are described under electromagnetic radiation, for most of history, visible light was the only known part of the electromagnetic spectrum. The ancient Greeks recognized that light traveled in straight lines and studied some of its properties, the study of light continued, and during the 16th and 17th centuries conflicting theories regarded light as either a wave or a particle. The first discovery of electromagnetic radiation other than visible light came in 1800 and he was studying the temperature of different colors by moving a thermometer through light split by a prism. He noticed that the highest temperature was beyond red and he theorized that this temperature change was due to calorific rays that were a type of light ray that could not be seen. The next year, Johann Ritter, working at the end of the spectrum. These behaved similarly to visible light rays, but were beyond them in the spectrum. They were later renamed ultraviolet radiation, during the 1860s James Maxwell developed four partial differential equations for the electromagnetic field. Two of these equations predicted the possibility of, and behavior of, analyzing the speed of these theoretical waves, Maxwell realized that they must travel at a speed that was about the known speed of light. This startling coincidence in value led Maxwell to make the inference that light itself is a type of electromagnetic wave, maxwells equations predicted an infinite number of frequencies of electromagnetic waves, all traveling at the speed of light. This was the first indication of the existence of the electromagnetic spectrum. Maxwells predicted waves included waves at very low compared to infrared. Hertz found the waves and was able to infer that they traveled at the speed of light, Hertz also demonstrated that the new radiation could be both reflected and refracted by various dielectric media, in the same manner as light. For example, Hertz was able to focus the waves using a lens made of tree resin, in a later experiment, Hertz similarly produced and measured the properties of microwaves
Electromagnetic spectrum
–
The electromagnetic spectrum
23.
Indigo dye
–
Indigo dye is an organic compound with a distinctive blue color. Historically, indigo was a dye extracted from the leaves of certain plants. A large percentage of indigo dye produced today – several thousand each year – is synthetic. It is the blue often associated with blue jeans, the primary use for indigo is as a dye for cotton yarn, which is mainly for the production of denim cloth for blue jeans. On average, a pair of blue jean trousers requires 3–12 g of indigo, small amounts are used for dyeing wool and silk. Indigo carmine, or indigo, is a derivative which is also used as a colorant. About 20 thousand tons are produced annually, again mainly for blue jeans and it is also used as a food colorant, and is listed in the United States as FD&C Blue No.2. A variety of plants have provided indigo throughout history, but most natural indigo was obtained from those in the genus Indigofera, the primary commercial indigo species in Asia was true indigo. A common alternative used in the relatively colder subtropical locations such as Japans Ryukyu Islands, dyers knotweed was the most important blue dye in East Asia until the arrival of the Indigofera species from the south, which yield more dye. In Central and South America, the species grown is I. suffruticosa, in Europe woad containing the same dye was used for blue-dying. Several plants contain indigo, but low concentrations make them difficult to work with, natural sources also include mollusks, the Murex sea snails produce a mixture of indigo and dibromoindigo which together produce a range of purple hues known as Tyrian purple. Light exposure during part of the process can convert the dibromoindigo into indigo resulting in blue hues known as royal blue or hyacinth purple. The precursor to indigo is indican, a colorless, water-soluble derivative of the amino acid tryptophan, indican readily hydrolyzes to release β-D-glucose and indoxyl. Oxidation by exposure to air converts indoxyl to indigo, indican was obtained from the processing of the plants leaves, which contain as much as 0. 2–0. 8% of this compound. The leaves were soaked in water and fermented to convert the glycoside indican present in the plant to the blue dye indigotin, the precipitate from the fermented leaf solution was mixed with a strong base such as lye, pressed into cakes, dried, and powdered. The powder was mixed with various other substances to produce different shades of blue. Indigo was used in India, which was also the earliest major center for its production, the I. tinctoria species was domesticated in India. Indigo, used as a dye, made its way to the Greeks and the Romans, Indigo is among the oldest dyes to be used for textile dyeing and printing
Indigo dye
–
Indigo
Indigo dye
–
Indigo dye
Indigo dye
–
Indigo, historical dye collection of the
Technical University of Dresden, Germany
Indigo dye
–
Cake of indigo, about 2 cm
24.
Indigofera tinctoria
–
Indigofera tinctoria, also called true indigo, is a species of plant from the bean family that was one of the original sources of indigo dye. It has been naturalized to tropical and temperate Asia, as well as parts of Africa, today most dye is synthetic, but natural dye from I. tinctoria is still available, marketed as natural coloring where it is known as tarum in Indonesia and nila in Malaysia. In Iran and areas of the former Soviet Union it is known as basma, the plant is also widely grown as a soil-improving groundcover. True indigo is a one to two meters high. It may be an annual, biennial, or perennial, depending on the climate in which it is grown and it has light green pinnate leaves and sheafs of pink or violet flowers. The plant is a legume, so it is rotated into fields to improve the soil in the way that other legume crops such as alfalfa. Dye is obtained from the processing of the plants leaves and they are soaked in water and fermented in order to convert the glycoside indican naturally present in the plant to the blue dye indigotin. The precipitate from the fermented leaf solution is mixed with a base such as lye. The rotenoids deguelin, dehydrodeguelin, rotenol, rotenone, tephrosin, marco Polo was the first to report on the preparation of indigo in India. Indigo was quite often used in European easel painting since the Middle Ages
Indigofera tinctoria
–
Indigofera tinctoria
25.
English language
–
English /ˈɪŋɡlɪʃ/ is a West Germanic language that was first spoken in early medieval England and is now the global lingua franca. Named after the Angles, one of the Germanic tribes that migrated to England, English is either the official language or one of the official languages in almost 60 sovereign states. It is the third most common language in the world, after Mandarin. It is the most widely learned second language and a language of the United Nations, of the European Union. It is the most widely spoken Germanic language, accounting for at least 70% of speakers of this Indo-European branch, English has developed over the course of more than 1,400 years. The earliest forms of English, a set of Anglo-Frisian dialects brought to Great Britain by Anglo-Saxon settlers in the century, are called Old English. Middle English began in the late 11th century with the Norman conquest of England, Early Modern English began in the late 15th century with the introduction of the printing press to London and the King James Bible, and the start of the Great Vowel Shift. Through the worldwide influence of the British Empire, modern English spread around the world from the 17th to mid-20th centuries, English is an Indo-European language, and belongs to the West Germanic group of the Germanic languages. Most closely related to English are the Frisian languages, and English, Old Saxon and its descendent Low German languages are also closely related, and sometimes Low German, English, and Frisian are grouped together as the Ingvaeonic or North Sea Germanic languages. Modern English descends from Middle English, which in turn descends from Old English, particular dialects of Old and Middle English also developed into a number of other English languages, including Scots and the extinct Fingallian and Forth and Bargy dialects of Ireland. English is classified as a Germanic language because it shares new language features with other Germanic languages such as Dutch, German and these shared innovations show that the languages have descended from a single common ancestor, which linguists call Proto-Germanic. Through Grimms law, the word for foot begins with /f/ in Germanic languages, English is classified as an Anglo-Frisian language because Frisian and English share other features, such as the palatalisation of consonants that were velar consonants in Proto-Germanic. The earliest form of English is called Old English or Anglo-Saxon, in the fifth century, the Anglo-Saxons settled Britain and the Romans withdrew from Britain. England and English are named after the Angles, Old English was divided into four dialects, the Anglian dialects, Mercian and Northumbrian, and the Saxon dialects, Kentish and West Saxon. Through the educational reforms of King Alfred in the century and the influence of the kingdom of Wessex. The epic poem Beowulf is written in West Saxon, and the earliest English poem, Modern English developed mainly from Mercian, but the Scots language developed from Northumbrian. A few short inscriptions from the period of Old English were written using a runic script. By the sixth century, a Latin alphabet was adopted, written with half-uncial letterforms and it included the runic letters wynn ⟨ƿ⟩ and thorn ⟨þ⟩, and the modified Latin letters eth ⟨ð⟩, and ash ⟨æ⟩
English language
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The opening to the Old English epic poem
Beowulf,
handwritten in
half-uncial script: Hƿæt ƿē Gārde/na ingēar dagum þēod cyninga / þrym ge frunon... "Listen! We of the Spear-Danes from days of yore have heard of the glory of the folk-kings..."
English language
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Countries of the world where English is a majority native language
English language
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Title page of Geoffrey Chaucer's
Canterbury Tales c.1400
26.
Indigofera
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Indigofera is a large genus of over 750 species of flowering plants belonging to the family Fabaceae. They are widely distributed throughout the tropical and subtropical regions of the world, species of Indigofera are mostly shrubs, though some are small trees or annual or perennial herbs. Racemes of flowers grow in the leaf axils, most species have flowers in hues of red, but there are a few white- and yellow-flowered species. The fruit is a pod of varying size and shape. Indigofera is a genus that has shown unique characteristics that make it an interesting candidate as a potential perennial crop. Specifically, there is variation among species with a number of unique characteristics. Some examples of this diversity include differences in thickness, fruit type. Indigofera is a genus that also shows some unique characteristics in its flowering morphology. For example, one characteristic of Indigofera is that it demonstrates an open carpel not seen among many species. The types of produced by different species of Indigofera can also be divided into broad categories that again show great variation. The three basic types of categories can be separated by their curvature including straight, slightly curved. Another way to categorize Indigofera is by its pericarp thickness, several species, especially Indigofera tinctoria and Indigofera suffruticosa, are used to produce the dye indigo. Scraps of Indigo-dyed fabric likely dyed with plants from the genus Indigofera discovered at Huaca Prieta predate Egyptian indigo-dyed fabrics by more than 1,500 years, exports of the crop did not expand until the mid-to late 18th century. When Eliza Lucas Pinckney and enslaved Africans successfully cultivated new strains near Charleston it became the second most important cash crop in the colony before the American Revolution and it comprised more than one-third of all exports in value. The chemical aniline, from many important dyes are derived, was first synthesized from Indigofera suffruticosa. In Indonesia, the Sundanese use Indigofera tinctoria as dye for batik, marco Polo was the first to report on the preparation of indigo in India. Indigo was quite often used in European easel painting during the Middle Ages, several species of this group are used to alleviate pain. The herbs are generally regarded as an analgesic with anti-inflammatory activity, Indigofera articulata was used for toothache, and Indigofera oblongifolia was used as an anti-inflammatory for insect stings, snakebites, and swellings
Indigofera
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Indigofera
Indigofera
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Indigofera pendula
Indigofera
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Indigofera spicata
Indigofera
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Indigofera astragalina
27.
Egypt
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Egypt, officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia by a land bridge formed by the Sinai Peninsula. Egypt is a Mediterranean country bordered by the Gaza Strip and Israel to the northeast, the Gulf of Aqaba to the east, the Red Sea to the east and south, Sudan to the south, and Libya to the west. Across the Gulf of Aqaba lies Jordan, and across from the Sinai Peninsula lies Saudi Arabia, although Jordan and it is the worlds only contiguous Afrasian nation. Egypt has among the longest histories of any country, emerging as one of the worlds first nation states in the tenth millennium BC. Considered a cradle of civilisation, Ancient Egypt experienced some of the earliest developments of writing, agriculture, urbanisation, organised religion and central government. One of the earliest centres of Christianity, Egypt was Islamised in the century and remains a predominantly Muslim country. With over 92 million inhabitants, Egypt is the most populous country in North Africa and the Arab world, the third-most populous in Africa, and the fifteenth-most populous in the world. The great majority of its people live near the banks of the Nile River, an area of about 40,000 square kilometres, the large regions of the Sahara desert, which constitute most of Egypts territory, are sparsely inhabited. About half of Egypts residents live in areas, with most spread across the densely populated centres of greater Cairo, Alexandria. Modern Egypt is considered to be a regional and middle power, with significant cultural, political, and military influence in North Africa, the Middle East and the Muslim world. Egypts economy is one of the largest and most diversified in the Middle East, Egypt is a member of the United Nations, Non-Aligned Movement, Arab League, African Union, and Organisation of Islamic Cooperation. Miṣr is the Classical Quranic Arabic and modern name of Egypt. The name is of Semitic origin, directly cognate with other Semitic words for Egypt such as the Hebrew מִצְרַיִם, the oldest attestation of this name for Egypt is the Akkadian
Egypt
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The
Giza Necropolis is the oldest of the
ancient Wonders and the only one still in existence.
Egypt
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Flag
Egypt
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The Greek Ptolemaic queen
Cleopatra VII and her son by Julius Caesar,
Caesarion at the
Temple of Dendera.
Egypt
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The 1803
Cedid Atlas, showing
Ottoman Egypt.
28.
Peru
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Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the west by the Pacific Ocean. Peruvian territory was home to ancient cultures spanning from the Norte Chico civilization in Caral, one of the oldest in the world, to the Inca Empire, the largest state in Pre-Columbian America. The Spanish Empire conquered the region in the 16th century and established a Viceroyalty with its capital in Lima, ideas of political autonomy later spread throughout Spanish America and Peru gained its independence, which was formally proclaimed in 1821. After the battle of Ayacucho, three years after proclamation, Peru ensured its independence, subsequently, the country has undergone changes in government from oligarchic to democratic systems. Peru has gone through periods of political unrest and internal conflict as well as periods of stability, Peru is a representative democratic republic divided into 25 regions. It is a country with a high Human Development Index score. Its main economic activities include mining, manufacturing, agriculture and fishing, the Peruvian population, estimated at 31.2 million in 2015, is multiethnic, including Amerindians, Europeans, Africans and Asians. The main spoken language is Spanish, although a significant number of Peruvians speak Quechua or other native languages and this mixture of cultural traditions has resulted in a wide diversity of expressions in fields such as art, cuisine, literature, and music. The name of the country may be derived from Birú, the name of a ruler who lived near the Bay of San Miguel, Panama. When his possessions were visited by Spanish explorers in 1522, they were the southernmost part of the New World yet known to Europeans, thus, when Francisco Pizarro explored the regions farther south, they came to be designated Birú or Perú. An alternative history is provided by the contemporary writer Inca Garcilasco de la Vega, son of an Inca princess, the Spanish Crown gave the name legal status with the 1529 Capitulación de Toledo, which designated the newly encountered Inca Empire as the province of Peru. Under Spanish rule, the country adopted the denomination Viceroyalty of Peru, the earliest evidences of human presence in Peruvian territory have been dated to approximately 9,000 BC. Andean societies were based on agriculture, using such as irrigation and terracing, camelid husbandry. Organization relied on reciprocity and redistribution because these societies had no notion of market or money, the oldest known complex society in Peru, the Norte Chico civilization, flourished along the coast of the Pacific Ocean between 3,000 and 1,800 BC. These early developments were followed by archaeological cultures that developed mostly around the coastal, the Cupisnique culture which flourished from around 1000 to 200 BC along what is now Perus Pacific Coast was an example of early pre-Incan culture. The Chavín culture that developed from 1500 to 300 BC was probably more of a religious than a political phenomenon, on the coast, these included the civilizations of the Paracas, Nazca, Wari, and the more outstanding Chimu and Mochica. Their capital was at Chan Chan outside of modern-day Trujillo, in the 15th century, the Incas emerged as a powerful state which, in the span of a century, formed the largest empire in pre-Columbian America with their capital in Cusco
Peru
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Sculpted
Chavin head embedded in one of the walls of the temple of
Chavín de Huantar
Peru
Peru
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A
Moche ceramic vessel from the 5th century depicting a man's head
Peru
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The citadel of
Machu Picchu, an iconic symbol of pre-Columbian Peru
29.
Huaca Prieta
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Huaca Prieta is the site of a prehistoric settlement beside the Pacific Ocean in the Chicama Valley, just north of Trujillo, La Libertad Province, Peru. It is a part of the El Brujo Archaeological Complex, which also includes Moche sites, Huaca Prieta was occupied as early as 4700 BC, before the ceramics were introduced. It consisted of a mound of ash, stones, textiles, plants and shells, with some burials. It was first excavated by Junius B, Bird in 1946–1947 who excavated three large test pits in or beside it. The many stone artifacts were not fancy—fish net weights, flakes and simple pebble tools, in the upper part of the mound there were many underground structures of unknown function, some with burials. They were made of cobblestones cemented with an ash-water mixture, the inhabitants fished, gathered shellfish, and grew fruit, gourds, squash, peppers, beans, tubers and, importantly, cotton. There is a low mound 70–170 m to the north where Bird excavated three test pits and he found many ruins and much refuse, including ceramics of the Guañape, Early Cupisnique and Cupisnique cultures. The last is linked to the highland Chavín culture, a large tsunami damaged both mounds leaving a thick layer of cobblestones just north of the preceramic mound, at about 850 BCE, between the two Cupisnique phases. Until recently, it was beilieved that maize was introduced to the rather late. In 2012, it was reported that corncobs found at two ancient sites in Peru may date from as early as 4700 B. C and this suggests that people living along the coast of northern Peru were already eating corn by that time. These results were reported by Dolores Piperno, and other scientists from Washingtons National Museum of Natural History This is the earliest maize discovered so far in South America, in 2016, 6000-year-old dyed cotton fabric was discovered at the Preceramic site of Huaca Prieta. Analysis of the pigment identified it as indigotin, an indigoid dye and this marks the earliest recorded use of indigo dye to date, predating the use of indigo in Egypts Fifth Dynasty by about 1,500 years. Andean preceramic Norte Chico civilization Cupisnique culture Huaca Ventarron K. Kris Hirst, Huaca Prieta, Formative Mound Construction in Peru archaeology. about. com
Huaca Prieta
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Panoramic view of Huaca Prieta
Huaca Prieta
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Cotton cloth fragment from Huaca Prieta, 2500 BC -
American Museum of Natural History, New York
30.
Pliny the Elder
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In the latter number will be my uncle, by virtue of his own and of your compositions. Pliny is referring to the fact that Tacitus relied on his uncles now missing work on the History of the German Wars. The wind caused by the sixth and largest pyroclastic surge of the eruption would not allow his ship to leave the shore, and Pliny probably died during this event. Plinys dates are pinned to the eruption of Mount Vesuvius in AD79 and a statement of his nephew that he died in his 56th year, Pliny was the son of an equestrian, Gaius Plinius Celer, and his wife, Marcella. Neither the younger nor the elder Pliny mention the names and their ultimate source is a fragmentary inscription found in a field in Verona and recorded by the 16th century Augustinian monk Onofrio Panvinio at Verona. The reading of the inscription depends on the reconstruction, but in all cases the names come through, whether he was an augur and whether she was named Grania Marcella are less certain. Jean Hardouin presents a statement from a source that he claims was ancient, that Pliny was from Verona. Hardouin also cites the conterraneity of Catullus, additional efforts to connect Celer and Marcella with other gentes are highly speculative. Hardouin is the scholar to use his unknown source. He kept statues of his ancestors there, a statue of Pliny on the facade of the Duomo of Como celebrates him as a native son. He had a sister, Plinia, who married into the Caecilii and was the mother of his nephew, Pliny the Younger, whose letters describe his work and study regimen in detail. In one of his letters to Tacitus, Pliny the Younger details how his uncles breakfasts would be light and simple following the customs of our forefathers. This shows that Pliny the Younger wanted it to be conveyed that Pliny the Elder was a good Roman and this statement would have pleased Tacitus. Two inscriptions identifying the hometown of Pliny the Younger as Como take precedence over the Verona theory, one commemorates the youngers career as imperial magistrate and details his considerable charitable and municipal expenses on behalf of the people of Como. Another identifies his father Lucius village as Fecchio near Como and it is likely therefore that Plinia was a local girl and Pliny the Elder, her brother, was from Como. Gaius was a member of the Plinii gens and he did not take his fathers cognomen, Celer, but assumed his own, Secundus. As his adopted son took the same cognomen, Pliny founded a branch, no earlier instances of the Plinii are known. In 59 BC, only about 82 years before Plinys birth, Julius Caesar founded Novum Comum as a colonia to secure the region against the Alpine tribes, whom he had been unable to defeat
Pliny the Elder
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One of the
Xanten Horse-Phalerae located in the
British Museum, measuring 10.5 cm (4.1 in). It bears an inscription formed from punched dots: PLINIO PRAEF EQ; i.e., Plinio praefecto equitum, "Pliny prefect of cavalry". It was perhaps issued to every man in Pliny's unit. The figure is the bust of the emperor.
Pliny the Elder
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Pliny the Elder, as imagined by a 19th-century artist. No contemporary depiction of Pliny is known to survive.
Pliny the Elder
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City and Lake of
Como, painted by
Jean-Baptiste-Camille Corot, 1834.
Pliny the Elder
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The temple of
Castor and Pollux in Rome
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