1.
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
2.
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.
3.
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.
4.
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.
5.
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.
6.
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.
7.
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.
8.
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).
9.
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).
10.
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 ′
11.
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
12.
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)
13.
Malva sylvestris
–
Malva sylvestris is a species of the mallow genus Malva in the family of Malvaceae and is considered to be the type species for the genus. It is one of several species of different genera sometimes referred to as Creeping charlie, sylvestris is pleasing in appearance when it first starts to flower, but as the summer advances, the leaves lose their deep green color and the stems assume a ragged appearance. Stems and leaves, A thick, round and strong stem, downy, with hairs radiating from a common center and prominent veins on the underside. Petiole either 2 to 6 centimeters or 2 to 13 centimeters long, M. sylvestris has an epicalyx with oblong segments, two-thirds as long as calyx or 2–3 millimeters long and 1.5 millimeters wide. Its calyx is free to the middle, 3–6 millimeters long, slender flower stalks that are either 2 centimeters long or 1 to 3 centimeters long. Ten broad carpels in axillary clusters, stamen about 3 millimters long, radiating from the center with short soft hairs, fruits Nutlets strongly reticulate (10–12 mericarps, usually without hair, with sharp angle between dorsal and lateral surfaces, 5–6 millimters in diameter. As a native Malva sylvestris spreads itself on waste and rough ground, by roads and railways throughout lowland England, Wales and Channel Islands, Siberia and scattered elsewhere. It has been introduced to and has naturalised in eastern Australia, in the United States, Canada. Decoration In the past, the flowers were spread on doorways, food The young leaves when boiled is a wholesome vegetable and was eaten in several parts of Europe in the 19th century. Medicinal M. sylvestris has been used medicinally since ancient times, mucilage is present in many of the Malvaceae family including M. sylvestris, especially the fruit. The seeds are used internally in a decoction or herbal tea as a demulcent and diuretic, mallow can also be taken internally for its laxative effect. Other The species has long used as a natural yellow dye, perhaps more recently, cream color, yellow and green dyes can be obtained from the plant. A tincture of the flowers can make a very sensitive test for alkalis, Plants previously often described as Malva sylvestris var. malaca are now considered a Cultivar Group Malva sylvestris Mauritiana Group. It is often grown as a plant for its attractive flowers. Numerous cultivars have been selected and named, Malva sylvestris L. Canescens group Every part except for the flower is covered with dense white woolly hair, growing in the Montpellier region of France, and on the Balearic Isles. Some 19th-century botanical works called this group Malva sylvestris L. var. canescens, the virus can be found in Tasmania, Brazil, the former Czechoslovakia, Germany, Israel, Italy, Portugal, California, Russia and the former Yugoslavia. It also contains the naphtoquinone malvone A, which is also a phytoalaxin, data related to Malva sylvestris at Wikispecies Porter, Noah, ed. Websters entry needed. Springfield, Massachusetts, C. & G. Merriam Co, africa Malva sylvestris L. record n°81830
Malva sylvestris
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Malva sylvestris
Malva sylvestris
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Habit
Malva sylvestris
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Leaf
Malva sylvestris
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Flower
14.
Purple
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Purple is a color intermediate between blue and red. It is similar to violet, but unlike violet, which is a color with its own wavelength on the visible spectrum of light, purple is a composite color made by combining red. According to surveys In Europe and the U. S. purple is the color most often associated with royalty, magic, mystery, when combined with pink, it is associated with eroticism, femininity and seduction. Purple was the color worn by Roman magistrates, it became the color worn by the rulers of the Byzantine Empire and the Holy Roman Empire. Similarly in Japan, the color is associated with the Emperor. The first recorded use of the purple in the English language was in the year 975 AD. In heraldry, the word purpure is used for purple, in the traditional color wheel 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 is usually less saturated than purple. While the two look similar, from the point of view of optics there are important differences. There is no such thing as the wavelength of purple light, monochromatic violet light cannot be produced by the red-green-blue color system, the method used to create colors on a television screen or computer display. This means that when light strikes the eye, the S-cone should be stimulated strongly. The resulting color has the same hue as pure violet, however, one curious psychophysical difference between purple and violet is their appearance with an increase in luminance. Violet, as it brightens, looks more and more blue, the same effect does not happen with purple. This is the result of what is known as the Bezold–Brücke shift, while the scientific definitions of violet and purple are clear, the cultural definitions are more varied. The color known in antiquity as Tyrian purple ranged from crimson to a deep bluish-purple, in France, purple is defined as a dark red, inclined toward violet. The color called purple by the French, pourpre, contains red and half the amount of blue of the color called purple in the United States. In German, this color is sometimes called Purpurrot to avoid confusion, Purple first appeared in prehistoric art during the Neolithic era. These works have been dated to between 16,000 and 25,000 BC, as early as the 15th century BC the citizens of Sidon and Tyre, two cities on the coast of Ancient Phoenicia, were producing purple dye from a sea snail called the spiny dye-murex
Purple
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Purple is the color of royalty. A ticket for the coronation of
Elizabeth II (1953)
Purple
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Purple
Purple
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In Catholicism purple is a
liturgical color representing piety
Purple
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Purple has become a popular color for
neckties; it is less aggressive than red, but more active than blue.
15.
Malva
–
The genus is widespread throughout the temperate, subtropical and tropical regions of Africa, Asia and Europe. The word mallow is derived from Old English malwe, which was imported from Latin malva, cognate with Ancient Greek μαλάχη meaning mallow, a number of species, previously considered to belong to Lavatera, have been moved to Malva. The leaves are alternate, palmately lobed, the flowers are from 0. 5–5 cm diameter, with five pink or white petals. The colour mauve was in 1859 named after the French name for this plant, several species are widely grown as garden flowers, while some are invasive weeds, particularly in the Americas where they are not native. Many species are edible as leaf vegetables and commonly foraged in the West, known as ebegümeci in Turkish, it is used as vegetable in Turkey in various forms such as stuffing the leaves with bulgur or rice or using the boiled leaves as side dish. Malva verticillata is grown on a commercial scale in China. Very easily grown, short-lived perennials are grown as ornamental plants. Mild tasting, young leaves can be a substitute for lettuce. The buds and flowers can be used in salads, cultivation is by sowing the seeds directly outdoors in early spring. The seed is easy to collect, and they will spread themselves by seed. In Catalonia they use the leaves to cure stinging nettles sting, bodos of Northeast India cultivate a sub-species of malva called lapha and use it extensively in their traditional cuisine, although its use is not much known among other people of India. Malva Leaves are a highly cherished vegetable dish in north Indian state of Kashmir, Malva sp. leaves have been used in the traditional Austrian medicine internally as tea or externally as baths for treatment of disorders of the skin, gastrointestinal tract and respiratory tract. This plant is one of the earliest cited in recorded literature, the third century BC physician Diphilus of Siphnus wrote that juice lubricates the windpipe, nourishes, and is easily digested. Horace mentions it in reference to his own diet, which he describes as simple, Me pascunt olivae. Sources, Data related to Malva at Wikispecies
Malva
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Malva
Malva
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Malva sylvestris
16.
Flower
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A flower, sometimes known as a bloom or blossom, is the reproductive structure found in plants that are floral. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs, Flowers may facilitate outcrossing or allow selfing. Some flowers produce diaspores without fertilization, Flowers contain sporangia and are the site where gametophytes develop. Many flowers have evolved to be attractive to animals, so as to them to be vectors for the transfer of pollen. After fertilization, the ovary of the flower develops into fruit containing seeds, the essential parts of a flower can be considered in two parts, the vegetative part, consisting of petals and associated structures in the perianth, and the reproductive or sexual parts. A stereotypical flower consists of four kinds of structures attached to the tip of a short stalk, each of these kinds of parts is arranged in a whorl on the receptacle. The four main whorls are as follows, Collectively the calyx, corolla, the next whorl toward the apex, composed of units called petals, which are typically thin, soft and colored to attract animals that help the process of pollination. Androecium, the whorl, consisting of units called stamens. Stamens consist of two parts, a called a filament, topped by an anther where pollen is produced by meiosis. Gynoecium, the innermost whorl of a flower, consisting of one or more units called carpels, the carpel or multiple fused carpels form a hollow structure called an ovary, which produces ovules internally. Ovules are megasporangia and they in turn produce megaspores by meiosis which develop into female gametophytes and these give rise to egg cells. The gynoecium of a flower is described using an alternative terminology wherein the structure one sees in the innermost whorl is called a pistil. A pistil may consist of a carpel or a number of carpels fused together. The sticky tip of the pistil, the stigma, is the receptor of pollen, the supportive stalk, the style, becomes the pathway for pollen tubes to grow from pollen grains adhering to the stigma. The relationship to the gynoecium on the receptacle is described as hypogynous, perigynous, although the arrangement described above is considered typical, plant species show a wide variation in floral structure. These modifications have significance in the evolution of flowering plants and are used extensively by botanists to establish relationships among plant species, the four main parts of a flower are generally defined by their positions on the receptacle and not by their function. Many flowers lack some parts or parts may be modified into other functions and/or look like what is typically another part, in some families, like Ranunculaceae, the petals are greatly reduced and in many species the sepals are colorful and petal-like. Other flowers have modified stamens that are petal-like, the flowers of Peonies and Roses are mostly petaloid stamens
Flower
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A poster with flowers or clusters of flowers produced by twelve species of flowering plants from different families
Flower
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Main parts of a mature flower (
Ranunculus glaberrimus)
Flower
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Reproductive parts of Easter Lily (Lilium longiflorum). 1. Stigma, 2. Style, 3. Stamens, 4. Filament, 5. Petal
Flower
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Left: A normal zygomorphic Streptocarpus flower. Right: An aberrant peloric Streptocarpus flower. Both of these flowers appeared on the Streptocarpus hybrid 'Anderson's Crows' Wings'.
17.
English language
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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
18.
Grey
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Grey or gray is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is a color without color and this means that there are equal components of red, green, and blue. The variations in intensity of these colors uniformly produce different shades of grey and it is the color of a cloud-covered sky, of ash and of lead. The first recorded use of grey as a name in the English language was in AD700. Grey is the dominant spelling in European and Commonwealth English, although remained in common usage in the UK until the second half of the 20th century. Gray has been the preferred American spelling since approximately 1825, although grey is an accepted variant, in Europe and the United States, surveys show that grey is the color most commonly associated with neutrality, conformity, boredom, uncertainty, old age, indifference, and modesty. Only one percent of respondents chose it as their favorite color, Grey comes from the Middle English grai or grei, from the Anglo-Saxon graeg, and is related to the Dutch grauw and grijs and German grau. The first recorded use of grey as a name in the English language was in AD700. In antiquity and the Middle Ages, grey was the color of undyed wool, and thus was the color most commonly worn by peasants and the poor. It was also the color worn by monks of the Franciscan order, Cistercian Order, Franciscan monks in England and Scotland were commonly known as the Grey friars, and that name is now attached to many places in Great Britain. During the Renaissance and the Baroque, grey began to play an important role in fashion, Black became the most popular color of the nobility, particularly in Italy, France, and Spain, and grey and white were harmonious with it. Grey was also used for the drawing of oil paintings. The painting would first be composed in grey and white, and then the colors, made with thin transparent glazes, the grisaille beneath would provide the shading, visible through the layers of color. Sometimes the grisaille was simply left uncovered, giving the appearance of carved stone, Grey was a particularly good background color for gold and for skin tones. It became the most common background for the portraits of Rembrandt Van Rijn and for many of the paintings of El Greco, the palette of Rembrandt was composed almost entirely of somber colors. Over this he put a layer of glaze made of mixture of blue smalt, red ochre. Using these ingredients and many others, he made greys which had, according to art historian Philip Ball, the warm, dark and rich greys and browns served to emphasize the golden light on the faces in the paintings. Grey became a fashionable color in the 18th century, both for womens dresses and for mens waistcoats and coats
Grey
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Fog in
Venice
Grey
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Grey
Grey
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Blocks of
lead shielding a radioactive sample
Grey
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Column of volcanic ash from vent on Crater Peak,
Mount Spurr
19.
Violet (color)
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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)
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The
violet flower
Violet (color)
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Violet
Violet (color)
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Amethyst mineral
Violet (color)
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Lilac flowers
20.
Mauveine
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Mauveine, also known as aniline purple and Perkins mauve, was the first synthetic organic chemical dye, discovered serendipitously in 1856. It is also among the first chemical dyes to have been mass-produced, mauveine is a mixture of four related aromatic compounds differing in number and placement of methyl groups. Its organic synthesis involves dissolving aniline, p-toluidine, and o-toluidine in sulfuric acid and water in a roughly 1,1,2 ratio, mauveine A incorporates 2 molecules of aniline, one of p-toluidine, and one of o-toluidine. Mauveine B incorporates one molecule each of aniline, p-toluidine, in 1879, Perkin showed mauveine B related to safranines by oxidative/reductive loss of the p-tolyl group. In fact, safranine is a 2, 8-dimethyl phenazinium salt, whereas the produced by Perkin is presumed to be the 1. The molecular structure of mauveine proved difficult to determine, finally being identified in 1994. In 2007, two more were isolated and identified, mauveine B2, an isomer of mauveine B with methyl on different aryl group, and mauveine C, in 2008, additional mauveines and pseudomauveines were discovered, bringing the total number of these compounds up to 12. In 1856, William Henry Perkin, then age 18, was given a challenge by his professor, August Wilhelm von Hofmann, in one attempt, Perkin oxidized aniline using potassium dichromate, whose toluidine impurities reacted with the aniline and yielded a black solid—suggesting a failed organic synthesis. Cleaning the flask with alcohol, Perkin noticed purple portions of the solution, suitable as a dye of silk and other textiles, it was patented by Perkin, who the next year opened a dyeworks mass-producing it at Greenford on the banks of the Grand Union Canal in London. It was originally called aniline purple or Tyrian purple, the name of an ancient natural dye derived from mollusks, in 1859, it attained the name mauve in England via the French name for the mallow flower, and chemists later called it mauveine. By 1870, its great demand succumbed to newer synthetic colors in the dye industry launched by mauveine. In the early 20th century, the U. S. Perkin anniversary website Rotatable 3D models of mauveine are available using Jmol
Mauveine
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Letter from Perkin's son, with a sample of dyed silk
Mauveine
–
Professor
Charles Rees —wearing bow tie dyed with original sample of mauveine—holding
RSC journal named after Perkin
21.
Chemist
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A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties, chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms. Chemists carefully measure substance proportions, reaction rates, and other chemical properties, the word chemist is also used to address Pharmacists in Commonwealth English. Chemists may specialize in any number of subdisciplines of chemistry, materials scientists and metallurgists share much of the same education and skills with chemists. The roots of chemistry can be traced to the phenomenon of burning, fire was a mystical force that transformed one substance into another and thus was of primary interest to mankind. It was fire that led to the discovery of iron and glasses, after gold was discovered and became a precious metal, many people were interested to find a method that could convert other substances into gold. This led to the protoscience called alchemy, the word chemist is derived from the New Latin noun chimista, an abbreviation of alchimista. Alchemists discovered many chemical processes that led to the development of modern chemistry, Chemistry as we know it today, was invented by Antoine Lavoisier with his law of conservation of mass in 1783. The discoveries of the elements has a long history culminating in the creation of the periodic table by Dmitri Mendeleev. The Nobel Prize in Chemistry created in 1901 gives an excellent overview of chemical discovery since the start of the 20th century. Jobs for chemists usually require at least a degree, but many positions, especially those in research. At the Masters level and higher, students tend to specialize in a particular field, postdoctoral experience may be required for certain positions. Workers whose work involves chemistry, but not at a complexity requiring an education with a degree, are commonly referred to as chemical technicians. Such technicians commonly do such work as simpler, routine analyses for quality control or in clinical laboratories, there are also degrees specific to become a Chemical Technologist, which are somewhat distinct from those required when a student is interested in becoming a professional Chemist. A Chemical technologist is more involved in the management and operation of the equipment and they are part of the team of a chemical laboratory in which the quality of the raw material, intermediate products and finished products is analyzed. They also perform functions in the areas of quality control. The higher the level achieved in the field of Chemistry, the higher the responsibility given to that chemist. Chemistry, as a field, have so many applications that different tasks/objectives can be given to workers/scientists with these different levels of education and/or experience
Chemist
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The Apothecary or The Chemist by
Gabriël Metsu (c. 1651–67)
Chemist
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Russian chemist
Dmitri Mendeleev - author of the first modern
periodic table of elements
Chemist
–
Antoine Lavoisier (1743–94) is considered the "
Father of Modern Chemistry ".
Chemist
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A chemist prepares a new
fuel cell for testing.
22.
William Henry Perkin
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Sir William Henry Perkin, FRS was an English chemist best known for his accidental discovery of the first aniline dye, the purple mauveine. Though failing in trying to synthesise quinine for the treatment of malaria, William Perkin was born in the East End of London, the youngest of the seven children of George Perkin, a successful carpenter. His mother, Sarah, was of Scottish descent but moved to east London as a child and he was baptised in the parish church of St Pauls, Shadwell, which had been connected to such luminaries as James Cook, Jane Randolph Jefferson and John Wesley. At the age of 14, Perkin attended the City of London School, where he was taught by Thomas Hall, who fostered his scientific talent and encouraged him to pursue a career in chemistry. In 1853, at the age of 15, Perkin entered the Royal College of Chemistry in London. Hofmann had published a hypothesis on how it might be possible to synthesise quinine, perkin—who had by then become one of Hofmanns assistants—embarked on a series of experiments to try to achieve this end. Perkin, who had an interest in painting and photography, immediately became enthusiastic about this result and carried out trials with his friend Arthur Church. Since these experiments were not part of the work on quinine which had been assigned to Perkin and they satisfied themselves that they might be able to scale up production of the purple substance and commercialise it as a dye, which they called mauveine. Their initial experiments indicated that it dyed silk in a way which was stable when washed or exposed to light and they sent some samples to a dye works in Perth, Scotland, and received a very promising reply from the general manager of the company, Robert Pullar. Perkin filed for a patent in August 1856, when he was still only 18, at the time, all dyes used for colouring cloth were natural substances, many of which were expensive and labour-intensive to extract. Furthermore, many lacked stability, or fastness and its extraction was variable and complicated, and so Perkin and his brother realised that they had discovered a possible substitute whose production could be commercially successful. Everything seemed to fall into place by dint of hard work, with a little luck, after the discovery of mauveine, many new aniline dyes appeared, and factories producing them were constructed across Europe. This discovery was the subject of a question on the 2012 season of Eggheads, local lore has it that the colour of the nearby Grand Union Canal changed from week to week depending on the activity at Perkins Greenford dyeworks. During the next decade, the new German Empire was rapidly eclipsing Britain as the centre of Europes chemical industry, by the 1890s, Germany had a near-monopoly on the business and Perkin was compelled to sell off his holdings and retire. Perkin died in 1907 of pneumonia and other complications resulting from a burst appendix and he is buried in the grounds of Christchurch, Harrow, UK. Perkin married Jemima Harriet, the daughter of John Lissett, in 1859, Perkins second marriage was in 1866, to Alexandrine Caroline, daughter of Helman Mollwo, which resulted in one son and four daughters. Perkin received many honours in his lifetime, in June 1866, he was elected a Fellow of the Royal Society. In 1879, received their Royal Medal and, in 1889 and he was knighted in 1906, and in the same year was awarded the first Perkin Medal, established to commemorate the fiftieth anniversary of his discovery of mauveine
William Henry Perkin
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William Perkin (1838–1907)
William Henry Perkin
–
Perkin's Gravestone
William Henry Perkin
–
Blue plaque in
Greenford, near the
Grand Union Canal. Replaced in 2006.
23.
Aniline
–
Aniline is an organic compound with the formula C6H5NH2. Consisting of a group attached to an amino group, aniline is the prototypical aromatic amine. Its main use is in the manufacture of precursors to polyurethane, like most volatile amines, it possesses the odour of rotten fish. It ignites readily, burning with a smoky flame characteristic of aromatic compounds, the amine is nearly planar owing to conjugation of the lone pair with the aryl substituent. The C-N distance is correspondingly shorter, in aniline, the C-N and C-C distances are close to 1.39 Å, indicating the π-bonding between N and C. Industrial aniline production involves two steps, first, benzene is nitrated with a concentrated mixture of nitric acid and sulfuric acid at 50 to 60 °C to yield nitrobenzene. The nitrobenzene is then hydrogenated in the presence of metal catalysts, the reduction of nitrobenzene to aniline was first performed by Nikolay Zinin in 1842 using inorganic sulfide as a reductant. Aniline can alternatively be prepared from ammonia and phenol derived from the cumene process, many analogues of aniline are known where the phenyl group is further substituted. These include toluidines, xylidines, chloroanilines, aminobenzoic acids, nitroanilines and they often are prepared by nitration of the substituted aromatic compounds followed by reduction. For example, this approach is used to convert toluene into toluidines, the chemistry of aniline is rich because the compound has been cheaply available for many years. Below are some classes of its reactions, the oxidation of aniline has been heavily investigated, and can result in reactions localized at nitrogen or more commonly results in the formation of new C-N bonds. In alkaline solution, azobenzene results, whereas arsenic acid produces the violet-coloring matter violaniline, chromic acid converts it into quinone, whereas chlorates, in the presence of certain metallic salts, give aniline black. Hydrochloric acid and potassium chlorate give chloranil, potassium permanganate in neutral solution oxidizes it to nitrobenzene, in alkaline solution to azobenzene, ammonia and oxalic acid, in acid solution to aniline black. Hypochlorous acid gives 4-aminophenol and para-amino diphenylamine, oxidation with persulfate affords a variety of polyanilines compounds. These polymers exhibit rich redox and acid-base properties, like phenols, aniline derivatives are highly susceptible to electrophilic substitution reactions. Its high reactivity reflects that it is an enamine, which enhances the ability of the ring. For example, reaction of aniline with sulfuric acid at 180 °C produces sulfanilic acid, if bromine water is added to aniline, the bromine water is decolourised and a white precipitate of 2,4, 6-tribromophenylamine is formed. The largest scale industrial reaction of aniline involves its alkylation with formaldehyde, an idealized equation is shown,2 C6H5NH2 + CH2O → CH22 + H2O The resulting diamine is the precursor to 4, 4-MDI and related diisocyanates
Aniline
–
Cake of
indigo dye, which is prepared from aniline.
Aniline
24.
Dye
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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
Dye
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Yarn drying after being dyed in the early American tradition, at
Conner Prairie living history museum.
Dye
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Dyeing wool cloth, 1482: from a French translation of
Bartolomaeus Anglicus
Dye
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Historical collection of over 10,000 dyes at Technical University Dresden,
Germany
Dye
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RIT brand dye from mid-20th century Mexico, part of the permanent collection of the
Museo del Objeto del Objeto
25.
Murexide
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Murexide, also called ammonium purpurate or MX, is the ammonium salt of purpuric acid. It may be prepared by heating alloxantin in ammonia gas to 100 °C, in this process alloxantin is dissolved in a large excess of boiling absolute alcohol, and dry ammonia gas is passed into the solution for about three hours. The solution is filtered from the precipitated murexide, which is washed with absolute alcohol. The salt obtained in this way is in the anhydrous state, Murexide in its dry state has the appearance of a reddish purple powder, slightly soluble in water. In solution, its color ranges from yellow in strong acidic pH through reddish-purple in weakly acidic solutions to blue-purple in alkaline solutions, the pH for titration of calcium is 11.3. In the 1850s, French colorists and dye-producers, such as Depoully in Paris, succeeded in making murexide from abundant South American guano and it was then widely adopted in Britain, France and Germany. Murexide is used in chemistry as a complexometric indicator for complexometric titrations, most often of calcium ions. Due to the amounts needed for this purpose, it is often used in a 1,250 mixture with potassium sulfate. Murexide and methyl red are investigated as promising enhancers of sonochemical destruction of chlorinated hydrocarbon pollutants and this article incorporates text from a publication now in the public domain, Chisholm, Hugh, ed. Murexide
Murexide
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Murexide
Color coordinates
listen), mohv[3]) is a pale purple color[4][5] named after the mallow flower (French: mauve). The first use of the word mauve as a color was in 1796–98 according to the Oxford English Dictionary, but its use seems to have been rare before 1859. Another name for the color is mallow,[6] with the first recorded use of mallow as a color name in English in 1611.[7]
Media related to Mauve at Wikimedia Commons
