Category: Colour

  • Colour in Islamic Traditions

    Colour in Islamic Traditions

    There is a lot of disagreement about ‘colour in Islam’. Some colours appear to be recommended or forbidden. But this often differs between Quran and Hadith and different Islamic sects. There is very rich use of colour in arts and crafts in Islamic cultural traditions and modern visual creativity.

    Pan-Arab colours

    • White, black, green and red, dominate the flags of Arab states.

    Green

    Green (Arabic: أخضر‎‎) is considered the traditional colour of Islam.

    • The Arabic word for “greenness” is mentioned several times in the Quran, describing the state of the inhabitants of paradise. Reclining on green Cushions and rich Carpets of beauty — Sura 55, verse 76. Upon them will be green garments of fine silk and heavy brocade, and they will be adorned with bracelets of silver; and their Lord will give to them to drink of a Water Pure and Holy. — Sura 76, verse 21. Al-Khidr (“The Green One”) is a Qur’anic figure who met and traveled with Moses.
    • The Green Dome, traditional site of the tomb of Muhammad, was painted green on the order of sultan Abdul Hamid II (r. 1876–1909).
    • Green was used as the colour of the banners of the historical Fatimid Caliphate. The Umayyads fought under  green and gold banners. Green is also used in several national flags as a symbol of Islam. These include: Afghanistan, Algeria, Azerbaijan, Comoros, Iran, Mauritania, Pakistan, Saudi Arabia. and Sri Lanka.

    Black

    • The Abbasids chose black (blue) and fought under black banners.
    • It is often worn by Shi’ite Muslims, who mourn the death of Husayn ibn Ali, killed at the Battle of Karbala. Black cloaks are worn by the ayatollahs, the Shi’a clergy. In many Shi’a countries, a black turban is worn only by male sayids, men who descend from Muhammad through his daughter Fatimah and his son-in-law Ali.
    • Symbol of modesty in some Muslim cultures.  It is the colour of the chador worn by devout Iranian Shi’ite women
    • Black is considered the colour of mourning in Western and Mediterranean countries. But this is seen as a Christian tradition.

    White

    The colour white symbolizes purity and peace.

    • Many Muslims wear the colour white when they attend Friday prayers and when performing sacred rites of pilgrimage.
    • In Sunni tradition, Muhammad wore a white kufi (head cap) with a black amaana (turban).
    • The Umayyads chose white for their battle standards when they fought the Abbassid during the Caliphate period
    • It has appeared on many Islamic flags since.

    Red

    Has no religious significance.

    • Some claim the hadith forbids the wearing of pure red clothing, it should be mixed with patches of other colours
    • Various countries on the Persian Gulf have chosen red flags

     Blue and turquoise

    many Islamic towns in the middle east, tend to have blue color? for example, the also many houses in sana city of yemen also painted the windows and the doors in blue color? even the villages in santorini Island of greece also painted in blue and white?………..the nazar bonjuk of turkey also in the blue color. Do you think is it possible that they painted the houses in blue, blue green, white and light yellow is because those soft colors are counteract the high color of the heat desert?

    Turquoise

    The colour turquoise greenish blue, has a special cultural place in Islam, though apparently not clear religious significance.

    • decoration of mosques and other buildings in Middle East: blue town of Chefchaouen in Morocco, blue town of Sidi bu Said in Tunisia, blue mosque and blue rooms in Topkapi palace of Turkey, blue in mosques of Isfahan and Shiraz in Iran
    • used in coats of arms, so that they could not possibly be mistaken for their Muslim opponents in the heat of battle.

    Yellow

    • The yellow colour of gold symbolizes wisdom.

    Brown

    • Brown is often believed to symbolize purity and peace.

     

     

    Colour in Shar’ia texts

     

  • Japanese Colour Theories

    The traditional colours of Japan are a collection of colours traditionally used in Japanese art, literature, textiles such as kimono, and other Japanese arts and crafts.

    Standardisation of the Japanese colour wheel was conducted around 600AD and western recognition of it was as late as the mid-19th century, because Japan was largely secluded from the rest of the globe until that time.  

    Japanese Colour Wheel

    Consisting of the primary colours: Red, Yellow and Blue, as well as the neutrals, both Black and White, the Japanese colour wheel spins with reference to the natural elements and is used as a tool to interpret the Japanese theory itself.

    The earliest written history of Japan, which was a mix of fact and mythology, mentions the four oldest colour terms in the Japanese language: aka あか or red, kuro くろ or black, shiro しろ or white, and ao あお or blue. However, it has been proposed that these terms originally referred to the contrasting optical sensations of light and dark, clear and vague.

    With time, these ancient colour terms evolved to have the red, black, white and blue meanings in use today (as well as acquiring other symbolic meanings, which we’ll get to later). However, traces of the original four colours persist in modern Japanese. Most proverbs and surnames that mention colour, for example, often involve these four colours. Additionally, only these four colours can be prefixed with the “pure” and “genuine” ma , to give us makka 真っ赤まっか or bright red, makkuro 真っ黒まっくろ or pitch black, masshiro 真っ白まっしろ or pure white, massao 真っ青まっさお or deep blue.

    Similarly, the original ambiguity of ao appears to have stood the test of time. A vague, overlapping, blue-green colour band, termed “grue” in anthropological lingo, may be used to describe the bluish-green (or greenish-blue?) of ao – which is notorious for causing the Western confusion between aoshingou 青信号あおしんごう and “green traffic light.” Or aonegi 青ネギあおねぎ and “green spring onion.”

    The Japanese Cap and Rank System

    The traditional colours of Japan trace their historical origins to the Twelve Level Cap and Rank System which was established in 603 by Prince Shōtoku – the pioneer of japanese unification – and based on the five Chinese elements.

    In this system, rank and social hierarchy were displayed and determined by certain colors. Colors known as kinjiki (禁色, “forbidden colors“) were strictly reserved for the robes of the highest ranking government officials; for example, the color ōtan (orange) was used as the color for the robes of kuge and use by any other lower rank was prohibited.

    The original Japanese system consisted of 12 levels, symbolised by 2 shades of 6 colours. Dark and light shades of, purple, blue, red, yellow, white, and black were used to show virtue and demonstrate an official position. Purple being ranked 1, while black is ranked 12.

    Colors known as yurushiiro (許し色, “permissible colors”) were permitted for use by the common people.

    Many of the names of these colours originate from Chinese culture, where the hierarchical colour system was historically even more complex. Due to the long history of use of this color system, some variations in color and names exist.

    Other pigments

    The names of traditional colours are often related to native plants and animals, especially those used to make pigments and dyes. Certain colours and dyeing techniques have been used since the Asuka period, while others had been developed as late as the Meiji period when synthetic dyes became common.

    An example of this would be the Japanese color name, akaneiro 茜色あかねいろ, which was produced by creating a dye from the root of a plant called akane grass. Another perhaps more familiar example is azukiiro 小豆色あずきいろ, or the color of azuki beans (aka the most delicious thing ever, often the filling of daifuku mochi).

    Colours were also named after animals, the most popular choice seems to be the mouse, or nezumi, which is used to express grey tones. For example budou nezumi ぶどうネズミ, or grape mouse (purple grey), fuji nezumi 藤ネズミふじねずみ, or Fuji mouse (light purple grey), yanagi nezumi 柳鼠やなぎねずみ, or willow mouse (light green grey), and cha nezumi 茶鼠ちゃねずみ, or tea mouse (light brown grey).

    Japanese Colour Meanings

    Although there are these initial meanings attributed, there are a number of different interpretations of each colour in Japan. Semantics vary from island to island and some meanings overlap.

    Japanese Primary Colours

    • Earth (Yellow)
    • Wood (Blue)
    • Fire (Red)
    • Water (Black)
    • Metal (White)
    Earth (Yellow)

    Yellow represents the element of Earth and the directional Centre, but also encompasses links with the Sun and Summertime, along with the warmth of mid-summer, and concepts like the virtue of Fidelity. It also connotes of courage.

    But there are also a number of similarities between both eastern (courage) and western (cowardice) meanings. Saying that someone has a yellow beak is like calling them a rookie, and a yellow voice is associated with the high-pitched tones of shrieking children and angry women.   

    Wood (Blue)

    Blue has strictly secular connotations. One theory is that because the Japanese never worshiped an all-powerful god dwelling in heaven above, blue never became associated with lofty, religious sentiments. As well as emblematising the element of Wood, the directional East, Spring time, and Benevolence, the colour Blue encapsulates Femininity, Purity, Passivity and Calmness.

    Blue was a popular choice for:

    • ceramics, namely sometsuke 染付けそめつけ porcelain
    • fine art, namely the aizuri-e 藍摺り絵あいずりえ woodblock prints.
    • indigo dyeing industry that flourished in Shikoku during the Edo period. Kimonos are predominantly crafted in or dyed with this colour, due to the fact that Blue also reflects Japanese fashion. Young Japanese women traditionally wear blue to symbolise their innocence. Japanese business suits are often made in various shades of blue and students frequently wear blue “recruitment suits”, particularly for job interviews.
    Red

    Red came to be associated with authority and wealth, as attested to by red-sheathed samurai swords and ornamental combs. It also has ties to religion, as demonstrated by the red torii of Shinto shrines, whose shrine maidens are traditionally clad in red hakama はかま.

    Black

    Black exudes dignity and formality, and is used for the robes of Buddhist monks, as well as for montsuki 紋付もんつき, the kimono that bears the family crest.

    An ancient Japanese tradition known as ‘o-haguro’, which is the practice of dying one’s teeth black, considered beautiful at one point in Japanese history.

    Metal (White)

    Symbolic of Metal, White is a symbol of Purity and Innocence. White is godly and sacred places are strung with shimenawa 注連縄しめなわ  festooned with white shide 紙垂しで, or strewn with white pebbles or sand.

    It additionally connotes the West, the seasonal Fall, and the virtue of Justice. Aside from the black cap, Shinto priests are adorned completely in the purity of White.

    Intrinsically linked with the spirit in Japanese culture, the neutral noncolor that is White was traditionally used to represent mourning and grief.

    Secondary Colours

    Many other colours now have significant links with specific concepts.

    Green

    The word for both Blue and Green (ao – 青) was used to describe both colours and the word for Green is a much more recent linguistic emergence.   

    Nevertheless green is an incredibly popular and symbolic colour.

    • Existing in numerous shades, it is emblematic of Matcha green tea – Japan’s favourite hot beverage.
    • it represents Eternity, Life, Vegetation, Vitality, and a plethora of other meanings.
    Purple

    Royalty is linked with this colour across the globe; majestic and spiritually linked with divine rule. Purple is worn by the rich and upper-classes, to symbolise both Wealth and Prestige.

    Pink

    Pink holds great significance in Japanese culture: in fashion, in painting, in art, and in design, among other areas. As the dominant colour of springtime Japanese landscapes, thanks to the fields of blossoms, Pink represents Happiness, Youth, and new beginnings.   

    Resources

    https://en.wikipedia.org/wiki/Traditional_colors_of_Japan

    https://www.tofugu.com/japan/color-in-japan/

  • Chinese Colour Theories

    Chinese culture attaches certain values to colours, like which colours are considered auspicious (吉利) or inauspicious (不利). The Chinese word for “colour” is yánsè (顏色). In Classical Chinese, the character  (色) more accurately meant “colour in the face”, or “emotion”. It was generally used alone and often implied sexual desire or desirability. During the Tang Dynasty, the word yánsè came to mean ‘all colour’. A Chinese idiom with the meaning “many colours” or “multi-coloured”, Wǔyánliùsè (五顏六色), can also mean ‘colours’ in general.

    In Chinese mythology, the goddess, Nüwa, is said to have mended the Heavens after a disaster destroyed the original pillars that held up the skies, using five coloured-stones in these five auspicious colours to patch-up the crumbling heavens, accounting for the many colours that the skies can take-on.

    Theory of the Five Elements (Wuxing 五行)

    In traditional Chinese art and culture, black, red, qing (青) (a conflation of the idea of green and blue), white and yellow are viewed as standard colours. These colors correspond to the five elements (五行) of water, fire, wood, metal and earth, taught in traditional Chinese physics. Throughout the Shang, Tang, Zhou and Qin dynasties, China’s emperors used the Theory of the Five Elements to select colors. Other colors were considered by Confucius as ‘inferior’.

    ElementWoodFireEarthMetalWater
    ColorBlue / Azure / GreenRedYellowWhiteBlack
    Directioneastsouthcenterwestnorth
    PlanetJupiterMarsSaturnVenusMercury
    Heavenly creatureAzure Dragon
    青龍
    Vermilion Bird
    朱雀
    Yellow Dragon
    黃龍
    White Tiger
    白虎
    Black Tortoise
    玄武
    Heavenly Stems
    Wufang ShangdiCāngdìChidiHuangdiBaidiHeidi
    PhaseNew YangFull YangYin and Yang balanceNew YinFull Yin
    EnergyGenerativeExpansiveStabilizingContractingConserving
    SeasonSpringSummerChange of seasons
    (Every third month)
    AutumnWinter
    ClimateWindyHotDampDryCold
    DevelopmentSproutingBloomingRipeningWitheringDormant
    Livestockdogsheep/goatcattlechickenpig
    FruitChinese plumapricotjujubepeachChinese chestnut
    Grainwheatlegumericehemppearl millet
    Yellow

    Portrait of the Hongwu Emperor in a silk yellow dragon robe featuring embroidered the Yellow Dragon

    Yellow of a golden hue is considered the most beautiful and prestigious color.[2] The Chinese conception of yellow (huáng) is inclusive of many shades considered tan or brown in English and the primary association is with the earth rather than the sun. The Chinese saying Yellow generates Yin and Yang implies that yellow is the center of everything. Associated with but ranked above brown, yellow signifies neutrality and good luck. Yellow is sometimes paired with red in place of gold.

    The Yellow River is the cradle of Chinese civilisation. Yellow was the emperor’s color in Imperial China and is held as the symbolic color of the five legendary emperors of ancient China, such as the Yellow Emperor. The Yellow Dragon is the zoomorphic incarnation of the Yellow Emperor of the centre of the universe in Chinese religion and mythology. The Flag of the Qing dynasty featured golden yellow as the background. The Plain Yellow Banner and the Bordered Yellow Banner were two of the upper three banners of Later Jin and Qing dynasty.

    Yellow often decorates royal palaces, altars and temples, and the color was used in the dragon robes and attire of the emperors.[2] It was a rare honour to receive the imperial yellow jacket.

    Yellow also represents freedom from worldly cares and is thus esteemed in Buddhism. Monks’ garments are yellow, as are elements of Buddhist temples. Yellow is also used as a mourning color for Chinese Buddhists.

    Yellow is also symbolic of heroism, as opposed to the Western association of the color with cowardice.[3]

    Black

    Black (黑, hēi), corresponding to water, is generally understood as a neutral color.

    The I Ching or Book of Changes regards black as Heaven’s color. The saying “heaven and earth are black” was rooted in the observation that the northern sky was black for a long time. Ancient Chinese people believed Tiandi or the Heavenly Emperor resided in the North Star. The Taiji symbol uses black and white or red to represent the unity of yin and yang. Ancient Chinese people regarded black as the king of colours and honoured black more consistently than any other colour (??). Laozi said know the white, keep the blackand Taoists believe black is the colour of the Tao.??

    Black is also used in many negative contexts in idioms and common names. “Black help” (黑幫, hēibāng) is the usual name for Chinese organized crime and the Thick Black Theory of the late Qing intellectual Li Zongwu (, 1879–1943) is an exhortation to Machiavellianism.

    In modern China, black is used in clothing, especially in professional contexts. Black has less association with mourning than white in traditional Chinese culture but formal black jackets and slacks have become associated with international professionalism.

    White

    White (白, bái) corresponds with metal among the Five Elements and represents gold (?) and symbolises brightness, purity, and fulfilment. Light-coloured skin is highly valued by many Chinese, especially in consideration of women as potential brides.

    White is also the traditional colour of mourning, although white wedding gowns have become more popular since the Opening Up Policy.

    Red

    See also: Vermilion § Chinese red

    Red (t s hóng), vermilion (dān), and crimson (chì) are associated with masculine yang energy and fire, good fortune and joy. Red is the traditional color used during Chinese New Year and other celebrations, including weddings and wedding gowns. Chinese reds are traditionally inclusive of shades English might consider orange or warm brown.

    A hongbao—a red envelope stuffed with money, now frequently red 100 RMB notes—is the usual gift in Chinese communities for Chinese New Year, birthdays, marriages, bribes, and other special occasions. The red color of the packet symbolizes good luck. Red is strictly forbidden at funerals as it is traditionally symbolic of happiness. The names of the dead were previously written in red, so it is generally somewhat offensive to use red ink for Chinese names in contexts other than official seals.

    In the People’s Republic of China, red remains a very popular color and is affiliated with and used by the Communist Party and the government.

    Blue / Green

    Main article: Qing (color)

    Old Chinese did not make a blue-green distinction, having a single “verdant” color (青, qīng) that covered both. The clear blue sky and fresh green vegetables were considered shades of a single color which could even include black as its darkest hue in some contexts. Modern Standard Mandarin does make the blue-green distinction using  (t s 绿, “leafy”) for green and lán (t s , “indigo“) for blue.

    Qīng was associated with health, prosperity, and harmony. It was used for the roof tiles and ornate interior of the Temple of Heaven and in other structures to represent heaven. It is also the colour of most jade as well as the greenware pottery that was developed to imitate it.

    Separately, green hats are associated with infidelity and used as an idiom for a cuckold. This has caused uneasiness for Chinese Catholic bishops, who, in ecclesiastical heraldry, would normally have a green hat above their arms. Chinese bishops have compromised by using a violet hat for their coat of arms.

    Intermediary colours

    The five intermediary colors (五間色 wǔjiànsè) are formed as combinations of the five elemental colors. These are:[6]

    • 綠  “green”: The intermediary colour of the east, combination of central yellow and eastern blue
    • 碧  “emerald-blue”: The intermediary colour of the west, combination of eastern blue and western white
    • 紅 hóng “light-red”: The intermediary colour of the south, combination of western white and southern red
    • 紫  “violet”: The intermediary colour of the north, combination of southern red and northern black
    • 硫 liú “horse-brown”: The intermediary colour of the center, combination of northern black and central yellow

    Resources

    https://en.wikipedia.org/wiki/Color_in_Chinese_culture

    https://ltl-taiwan.com/chinese-colors/#chapter-1

  • Western Colour Theories

    Western colour theory was originally formulated in terms of three “primary” or “primitive” colours—red, yellow and blue (RYB)—because these colours were believed capable of mixing all other colours.

    Goethe’s colour wheel from his 1810 Theory of Colours

    18th and 19th Centuries

    The RYB primary colors became the foundation of 18th-century theories of color vision,[citation needed] as the fundamental sensory qualities that are blended in the perception of all physical colors, and conversely, in the physical mixture of pigments or dyes. These theories were enhanced by 18th-century investigations of a variety of purely psychological color effects, in particular the contrast between “complementary” or opposing hues that are produced by color afterimages and in the contrasting shadows in colored light. These ideas and many personal color observations were summarized in two founding documents in color theory: the Theory of Colours (1810) by the German poet Johann Wolfgang von Goethe, and The Law of Simultaneous Color Contrast (1839) by the French industrial chemist Michel Eugène ChevreulCharles Hayter published A New Practical Treatise on the Three Primitive Colours Assumed as a Perfect System of Rudimentary Information (London 1826), in which he described how all colors could be obtained from just three.

    Page from 1826 A New Practical Treatise on the Three Primitive Colours Assumed as a Perfect System of Rudimentary Information by Charles Hayter

    Subsequently, German and English scientists established in the late 19th century that color perception is best described in terms of a different set of primary colors—red, green and blue-violet (RGB)—modeled through the additive mixture of three monochromatic lights. Subsequent research anchored these primary colors in the differing responses to light by three types of color receptors or cones in the retina (trichromacy).

    For much of the 19th century artistic color theory either lagged behind scientific understanding or was augmented by science books written for the lay public, in particular Modern Chromatics (1879) by the American physicist Ogden Rood, and early color atlases developed by Albert Munsell (Munsell Book of Color, 1915, see Munsell color system) and Wilhelm Ostwald (Color Atlas, 1919).

    20th Century

    On this basis the quantitative description of the color mixture or colorimetry developed in the early 20th century, along with a series of increasingly sophisticated models of color space and color perception, such as the opponent process theory.

    Across the same period, industrial chemistry radically expanded the color range of lightfast synthetic pigments, allowing for substantially improved saturation in color mixtures of dyes, paints, and inks. It also created the dyes and chemical processes necessary for color photography. As a result, three-color printing became aesthetically and economically feasible in mass printed media, and the artists’ color theory was adapted to primary colors most effective in inks or photographic dyes: cyan, magenta, and yellow (CMY). (In printing, dark colors are supplemented by black ink, known as the CMYK system; in both printing and photography, white is provided by the color of the paper.) These CMY primary colors were reconciled with the RGB primaries, and subtractive color mixing with additive color mixing, by defining the CMY primaries as substances that absorbed only one of the retinal primary colors: cyan absorbs only red (−R+G+B), magenta only green (+R−G+B), and yellow only blue-violet (+R+G−B). It is important to add that the CMYK, or process, color printing is meant as an economical way of producing a wide range of colors for printing, but is deficient in reproducing certain colors, notably orange and slightly deficient in reproducing purples. A wider range of colors can be obtained with the addition of other colors to the printing process, such as in Pantone‘s Hexachrome printing ink system (six colors), among others.

    Munsell‘s 1905 color system represents colors using three color-making attributes, value (lightness), chroma, and hue.

    Major advances were made in the early 20th century by artists teaching or associated with the German Bauhaus, in particular Wassily KandinskyJohannes IttenFaber Birren and Josef Albers, whose writings mix speculation with an empirical or demonstration-based study of color design principles.

    Itten and Albers studied the interaction between hues and the ways in which our perception of hues and tones is altered radically by the other colours surrounding them.

    Impressionism
    Pointillim
    Fauvism
    Expressionism

    Alex Katz
    Andy Warhol
    Patrick Caulfield

  • The Yellow Book

    edited from Wikipedia The Yellow Book

    Cover of the Yellow Book by Aubrey Beardsley

    The Yellow Book was a British quarterly literary periodical that was published in London from 1894 to 1897. It was a leading journal of the British 1890s and lent its name to the “Yellow Nineties” and the magazine contained a wide range of literary and artistic genres, poetry, short stories, essays, book illustrations, portraits, and reproductions of paintings.

    It was published by Elkin Mathews and John Lane, and later by John Lane alone, and edited by the American Henry Harland.

    Aubrey Beardsley was its first art editor, and he has been credited with the idea of the yellow cover, with its association with illicit French fiction of the period. He obtained works by such artists as Charles Conder, William Rothenstein, John Singer Sargent, Walter Sickert, and Philip Wilson Steer. The literary content was no less distinguished; authors who contributed were: Max Beerbohm, Arnold Bennett, “Baron Corvo“, Ernest Dowson, George Gissing, Sir Edmund Gosse, Henry James, Richard Le Gallienne, Charlotte Mew, Arthur Symons, H. G. Wells, William Butler Yeats and Frank Swettenham. A notable feature was the inclusion of work by women writers and illustrators, among them Ella D’Arcy and Ethel Colburn Mayne (both also served as Harland’s subeditors), George Egerton, Charlotte Mew, Rosamund Marriott Watson, Ada Leverson, Netta and Nellie Syrett, and Ethel Reed.

    It was to some degree associated with Aestheticism and Decadence, but also style. The first issue of The Yellow Book‘s prospectus introduces it “as a book in form, a book in substance; a book beautiful to see and convenient to handle; a book with style, a book with finish; a book that every book-lover will love at first sight; a book that will make book-lovers of many who are now indifferent to books”. The periodical was priced at 5 shillings.

    Cover: The Yellow Book‘s brilliant colour immediately associated the periodical with illicit French novels – an anticipation, many thought, of the scurrilous content inside.  It was issued clothbound.

    Art separate from text:  Harland and Beardsley rejected the idea that the function of artwork was merely explanatory: “There is to be no connection whatever [between the text and illustrations]. [They] will be quite separate”. The equilibrium which The Yellow Book poses between art and text is emphasized by the separate title pages before each individual work whether literary or pictorial.

    Page layout: The Yellow Book‘s mise-en-page differed dramatically from current Victorian periodicals: “… its asymmetrically placed titles, lavish margins, abundance of white space, and relatively square page declare The Yellow Book’s specific and substantial debt to Whistler”. The use of white space is positive rather than negative, simultaneously drawing the reader’s eye to the blank page as an aesthetic and essentially created object. 

    Typography: The decision to print The Yellow Book in Caslon-old face further signified the ties which The Yellow Book held to the Revivalists. Caslon-old face, “an eighteenth-century revival of a seventeenth-century typographical style” became “the type-face of deliberate and principled reaction or anachronism”. A type-face generally reserved for devotional and ecclesiastical work, its use in the pages of The Yellow Book at once identified it with the “Religion of Beauty”.

    Use of catch-words on every page enhanced The Yellow Book‘s link to the obsolescent. Both antiquated and obtrusive, the catch-phrase interrupts the cognitive process of reading: “making-transparent … the physical sign which constitutes the act of reading; and in doing this, catch-words participate in the ‘pictorialization’ of typography”. By interrupting readers through the very use of irrelevant text, catch-words lend the printed word a solidity of form which is otherwise ignored.

  • Digital Printing

    THE PIXEL: A FUNDAMENTAL UNIT OF DIGITAL IMAGES

    Every digital image consists of a fundamental small-scale descriptor: THE PIXEL, invented by combining the words “PICture ELement.” Each pixel contains a series of numbers which describe its color or intensity. The precision to which a pixel can specify color is called its bit or color depth. The more pixels your image contains, the more detail it has the ability to describe (although more pixels alone don’t necessarily result in more detail; more on this later).

    PRINT SIZE: PIXELS PER INCH vs. DOTS PER INCH

    Since a pixel is just a unit of information, it is useless for describing real-world prints — unless you also specify their size. The terms pixels per inch (PPI) and dots per inch (DPI) were both introduced to relate this theoretical pixel unit to real-world visual resolution. These terms are often inaccurately interchanged — misleading the user about a device’s maximum print resolution (particularly with inkjet printers).

    “Pixels per inch” (PPI) is the more straightforward of the two terms. It describes just that: how many pixels an image contains per inch of distance (horizontally or vertically). PPI is also universal because it describes resolution in a way that doesn’t vary from device to device.

    “Dots per inch” (DPI) may seem deceptively simple at first, but the complication arises because multiple dots are often needed to create a single pixel — and this varies from device to device. In other words, a given DPI does not always lead to the same resolution. Using multiple dots to create each pixel is a process called “dithering.”

    Printers use dithering to create the appearance of more colors than they actually have. However, this trick comes at the expense of resolution, since dithering requires each pixel to be created from an even smaller pattern of dots. As a result, images will require more DPI than PPI in order to depict the same level of detail.

    In the above example, note how the dithered version is able to create the appearance of 128 pixel colors — even though it has far fewer dot colors (only 24). However, this result is only possible because each dot in the dithered image is much smaller than the pixels.

    The standard for prints done in a photo lab is about 300 PPI, but inkjet printers require several times this number of DPI (depending on the number of ink colors) for photographic quality. The required resolution also depends on the application; magazine and newspaper prints can get away with much less than 300 PPI.

    However, the more you try to enlarge a given image, the lower its PPI will become…

    MEGAPIXELS AND MAXIMUM PRINT SIZE

    A “megapixel” is simply a million pixels. If you require a certain resolution of detail (PPI), then there is a maximum print size you can achieve for a given number of megapixels. The following chart gives the maximum print sizes for several common camera megapixels.

    # of Megapixels Maximum 3:2 Print Size
    at 300 PPI: at 200 PPI:
    2 5.8″ x 3.8″ 8.7″ x 5.8″
    3 7.1″ x 4.7″ 10.6″ x 7.1″
    4 8.2″ x 5.4″ 12.2″ x 8.2″
    5 9.1″ x 6.1″ 13.7″ x 9.1″
    6 10.0″ x 6.7″ 15.0″ x 10.0″
    8 11.5″ x 7.7″ 17.3″ x 11.5″
    12 14.1″ x 9.4″ 21.2″ x 14.1″
    16 16.3″ x 10.9″ 24.5″ x 16.3″
    22 19.1″ x 12.8″ 28.7″ x 19.1″

    Note how a 2 megapixel camera cannot even make a standard 4×6 inch print at 300 PPI, whereas it requires a whopping 16 megapixels to make a 16×10 inch photo. This may be discouraging, but do not despair! Many will be happy with the sharpness provided by 200 PPI, although an even lower PPI may suffice if the viewing distance is large (see “Digital Photo Enlargement“). For example, most wall posters are often printed at less than 200 PPI, since it’s assumed that you won’t be inspecting them from 6 inches away.

    CAMERA & IMAGE ASPECT RATIO

    The print size calculations above assumed that the camera’s aspect ratio, or ratio of longest to shortest dimension, is the standard 3:2 used for 35 mm cameras. In fact, most compact cameras, monitors and TV screens have a 4:3 aspect ratio, while most digital SLR cameras are 3:2. Many other types exist though: some high end film equipment even use a 1:1 square image, and DVD movies are an elongated 16:9 ratio.

    This means that if your camera uses a 4:3 aspect ratio, but you need a 4 x 6 inch (3:2) print, then some of your megapixels will be wasted (11%). This should be considered if your camera has a different ratio than the desired print dimensions.

    Pixels themselves can also have their own aspect ratio, although this is less common. Certain video standards and earlier Nikon cameras have pixels with skewed dimensions.

    SENSOR SIZE: NOT ALL PIXELS ARE CREATED EQUAL

    Even if two cameras have the same number of pixels, it does not necessarily mean that the size of their pixels are also equal. The main distinguishing factor between a more expensive digital SLR and a compact camera is that the former has a much greater digital sensor area. This means that if both an SLR and a compact camera have the same number of pixels, the size of each pixel in the SLR camera will be much larger.

    Compact Camera Sensor
    SLR Camera Sensor

    Why does one care about how big the pixels are? A larger pixel has more light-gathering area, which means the light signal is stronger over a given interval of time.

    This usually results in an improved signal to noise ratio (SNR), which createsa smoother and more detailed image. Furthermore, the dynamic range of the images (range of light to dark which the camera can capture without becoming either black or clipping highlights) also increases with larger pixels. This is because each pixel well can contain more photons before it fills up and becomes completely white.

    The diagram below illustrates the relative size of several standard sensor sizes on the market today. Most digital SLR’s have either a 1.5X or 1.6X crop factor (compared to 35 mm film), although some high-end models actually have a digital sensor which has the same area as 35 mm. Sensor size labels given in inches do not reflect the actual diagonal size, but instead reflect the approximate diameter of the “imaging circle” (not fully utilized). Nevertheless, this number is in the specifications of most compact cameras.

    Why not just use the largest sensor possible? The main disadvantage of having a larger sensor is that they are much more expensive, so they are not always beneficial.

    Other factors are beyond the scope of this tutorial, however more can be read on the following points:larger sensors requiresmaller apertures in order to achieve the same depth of field, however they are alsoless susceptible to diffraction at a given aperture.

    Does all this mean it is bad to squeeze more pixels into the same sensor area? This will usually produce more noise, but only when viewed at 100% on your computer monitor. In an actual print, the higher megapixel model’s noise will be much more finely spaced — even though it appears noisier on screen (see “Image Noise: Frequency and Magnitude“). This advantage usually offsets any increase in noise when going to a larger megapixel model (with a few exceptions).

  • Colour in photography and film: digital colour management

     Sources

    Cambridge in Colour: Colour Management and Printing series

    Underlying concepts and principles: Human Perception; Bit DepthBasics of digital cameras: pixels

    Color Management from camera to display Part 1: Concept and Overview; Part 2: Color Spaces; Part 3: Color Space Conversion; Understanding Gamma Correction

    Bit Depth

    Every color pixel in a digital image is created through some combination of the three primary colors: red, green, and blue –  often referred to as a “color channel”. Bit depth quantifies how many unique colors are available in an image’s color palette in terms of the number of 0’s and 1’s, or “bits,” which are used to specify each color channel (bpc) or per pixel (bpp). Images with higher bit depths can encode more shades or colors – or intensity of values -since there are more combinations of 0’s and 1’s available.

    Most color images from digital cameras have 8-bits per channel and so they can use a total of eight 0’s and 1’s. This allows for 28 or 256 different combinations—translating into 256 different intensity values for each primary color. When all three primary colors are combined at each pixel, this allows for as many as 28*3 or 16,777,216 different colors, or “true color.” This is referred to as 24 bits per pixel since each pixel is composed of three 8-bit color channels. The number of colors available for any X-bit image is just 2X if X refers to the bits per pixel and 23X if X refers to the bits per channel. The following table illustrates different image types in terms of bits (bit depth), total colors available, and common names.

    Bits Per Pixel Number of Colors Available Common Name(s)
    1 2 Monochrome
    2 4 CGA
    4 16 EGA
    8 256 VGA
    16 65536 XGA, High Color
    24 16777216 SVGA, True Color
    32 16777216 + Transparency
    48 281 Trillion
    USEFUL TIPS
    • The human eye can only discern about 10 million different colors, so saving an image in any more than 24 bpp is excessive if the only intended purpose is for viewing. On the other hand, images with more than 24 bpp are still quite useful since they hold up better under post-processing (see “Posterization Tutorial“).
    • Color gradations in images with less than 8-bits per color channel can be clearly seen in the image histogram.
    • The available bit depth settings depend on the file type. Standard JPEG and TIFF files can only use 8-bits and 16-bits per channel, respectively.

    BASICS OF DIGITAL CAMERA PIXELS

    The continuous advance of digital camera technology can be quite confusing because new terms are constantly being introduced. This tutorial aims to clear up some of this digital pixel confusion — particularly for those who are either considering or have just purchased their first digital camera. Concepts such as sensor size, megapixels, dithering and print size are discussed.

    OVERVIEW OF COLOR MANAGEMENT

    “Color management” is a process where the color characteristics for every device in the imaging chain is known precisely and utilized in color reproduction. It often occurs behind the scenes and doesn’t require any intervention, but when color problems arise, understanding this process can be critical.

    In digital photography, this imaging chain usually starts with the camera and concludes with the final print, and may include a display device in between:

    digital imaging chain

    Many other imaging chains exist, but in general, any device which attempts to reproduce color can benefit from color management. For example, with photography it is often critical that your prints or online gallery appear how they were intended. Color management cannot guarantee identical color reproduction, as this is rarely possible, but it can at least give you more control over any changes which may occur.

    THE NEED FOR PROFILES & REFERENCE COLORS

    Color reproduction has a fundamental problem: a given “color number” doesn’t necessarily produce the same color in all devices. We use an example of spiciness to convey both why this creates a problem, and how it is managed.

    Let’s say that you’re at a restaurant and are about to order a spicy dish. Although you enjoy spiciness, your taste buds are quite sensitive, so you want to be careful that you specify a pleasurable amount. The dilemma is this: simply saying “medium” might convey one level of spice to a cook in Thailand, and a completely different level to someone from England. Restaurants could standardize this based on the number of peppers included in the dish, but this alone wouldn’t be sufficient. Spice also depends on how sensitive the taster is to each pepper:

    calibration table

    To solve your spiciness dilemma, you could undergo a one-time taste test where you eat a series of dishes, with each containing slightly more peppers (shown above). You could then create a personalized table to carry with you at restaurants which specifies that 3 equals “mild,” 5 equals “medium,” and so on (assuming that all peppers are the same). Next time, when you visit a restaurant and say “medium,” the waiter could look at your personal table and translate this into a standardized concentration of peppers. This waiter could then go to the cook and say to make the dish “extra mild,” knowing all too well what this concentration of peppers would actually mean to the cook.

    As a whole, this process involved (1) characterizing each person’s sensitivity to spice, (2)standardizing this spice based on a concentration of peppers and (3) being able to collectively use this information to translate the “medium” value from one person into an “extra mild” value for another. These same three principles are used to manage color.

    COLOR PROFILES

    A device’s color response is characterized similar to how the personalized spiciness table was created in the above example. Various numbers are sent to this device, and its output is measured in each instance:

    Input Number (Green) Output Color
    Device 1 Device 2
    200
    150
    100
    50

    Real-world color profiles include all three colors, more values, and are usually more sophisticated than the above table — but the same core principles apply. However, just as with the spiciness example, a profile on its own is insufficient. These profiles have to be recorded in relation to standardized reference colors, and you need color-aware software that can use these profiles to translate color between devices.

    COLOR MANAGEMENT OVERVIEW

    Putting it all together, the following diagram shows how these concepts might apply when converting color between a display device and a printer:

    display device printer output device
    Characterized
    Input Device
    Standardized
    Profile Connection Space
    Characterized
    Output Device
    Additive RGB Colors
    RGB
    Color Profile
    (color space)
    CMM Translation CMM Translation Subtractive CMYK Colors
    CMYK
    Color Profile
    (color space)
    1. Characterize. Every color-managed device requires a personalized table, or “color profile,” which characterizes the color response of that particular device.
    2. Standardize. Each color profile describes these colors relative to a standardized set of reference colors (the “Profile Connection Space”).
    3. Translate. Color-managed software then uses these standardized profiles to translate color from one device to another. This is usually performed by a color management module (CMM).

    The above color management system was standardized by the International Color Consortium (ICC), and is now used in most computers. It involves several key concepts: color profiles (discussed above), color spaces, and translation between color spaces.

    Color Space. This is just a way of referring to the collection of colors/shades that are described by a particular color profile. Put another way, it describes the set of all realizable color combinations. Color spaces are therefore useful tools for understanding the color compatibility between two different devices. See the tutorial on color spaces for more on this topic.

    Profile Connection Space (PCS). This is a color space that serves as a standardized reference (a “reference space”), since it is independent of any particular device’s characteristics. The PCS is usually the set of all visible colors defined by the Commission International de l’éclairage (CIE) and used by the ICC.

    Note: The thin trapezoidal region drawn within the PCS is what is called a “working space.” The working space is used in image editing programs (such as Adobe Photoshop), and defines the subset of colors available to work with when performing any image editing.

    Color Translation. The color management module (CMM) is the workhorse of color management, and is what performs all the calculations needed to translate from one color space into another. Contrary to previous examples, this is rarely a clean and simple process. For example, what if the printer weren’t capable of producing as intense a color as the display device? This is called a “gamut mismatch,” and would mean that accurate reproduction is impossible. In such cases the CMM therefore just has to aim for the best approximation that it can. See the tutorial on color space conversion for more on this topic.

    UNDERSTANDING GAMMA CORRECTION

    Gamma is an important but seldom understood characteristic of virtually all digital imaging systems. It defines the relationship between a pixel’s numerical value and its actual luminance. Without gamma, shades captured by digital cameras wouldn’t appear as they did to our eyes (on a standard monitor). It’s also referred to as gamma correction, gamma encoding or gamma compression, but these all refer to a similar concept. Understanding how gamma works can improve one’s exposure technique, in addition to helping one make the most of image editing.

    WHY GAMMA IS USEFUL

    1. Our eyes do not perceive light the way cameras do. With a digital camera, when twice the number of photons hit the sensor, it receives twice the signal (a “linear” relationship). Pretty logical, right? That’s not how our eyes work. Instead, we perceive twice the light as being only a fraction brighter — and increasingly so for higher light intensities (a “nonlinear” relationship).

    linear vs nonlinear gamma - cameras vs human eyes
    Reference Tone
    Perceived as 50% as Bright
    by Our Eyes
    Detected as 50% as Bright
    by the Camera

    Refer to the tutorial on the photoshop curves tool if you’re having trouble interpreting the graph.
    Accuracy of comparison depends on having a well-calibrated monitor set to a display gamma of 2.2.
    Actual perception will depend on viewing conditions, and may be affected by other nearby tones.
    For extremely dim scenes, such as under starlight, our eyes begin to see linearly like cameras do.

    Compared to a camera, we are much more sensitive to changes in dark tones than we are to similar changes in bright tones. There’s a biological reason for this peculiarity: it enables our vision to operate over a broader range of luminance. Otherwise the typical range in brightness we encounter outdoors would be too overwhelming.

    But how does all of this relate to gamma? In this case, gamma is what translates between our eye’s light sensitivity and that of the camera. When a digital image is saved, it’s therefore “gamma encoded” — so that twice the value in a file more closely corresponds to what we would perceive as being twice as bright.

    Technical Note: Gamma is defined by Vout = Vingamma , where Vout is the output luminance value and Vin is the input/actual luminance value. This formula causes the blue line above to curve. When gamma<1, the line arches upward, whereas the opposite occurs with gamma>1.

    2. Gamma encoded images store tones more efficiently. Since gamma encoding redistributes tonal levels closer to how our eyes perceive them, fewer bits are needed to describe a given tonal range. Otherwise, an excess of bits would be devoted to describe the brighter tones (where the camera is relatively more sensitive), and a shortage of bits would be left to describe the darker tones (where the camera is relatively less sensitive):

    Original: smooth 8-bit gradient (256 levels)
    Encoded using only 32 levels (5 bits)
    Linear
    Encoding:
    linearly encoded gradient
    Gamma
    Encoding:
    gamma encoded gradient

    Note: Above gamma encoded gradient shown using a standard value of 1/2.2
    See the tutorial on bit depth for a background on the relationship between levels and bits.

    Notice how the linear encoding uses insufficient levels to describe the dark tones — even though this leads to an excess of levels to describe the bright tones. On the other hand, the gamma encoded gradient distributes the tones roughly evenly across the entire range (“perceptually uniform”). This also ensures that subsequent image editing, color andhistograms are all based on natural, perceptually uniform tones.

    However, real-world images typically have at least 256 levels (8 bits), which is enough to make tones appear smooth and continuous in a print. If linear encoding were used instead, 8X as many levels (11 bits) would’ve been required to avoid image posterization.

    GAMMA WORKFLOW: ENCODING & CORRECTION

    Despite all of these benefits, gamma encoding adds a layer of complexity to the whole process of recording and displaying images. The next step is where most people get confused, so take this part slowly. A gamma encoded image has to have “gamma correction” applied when it is viewed — which effectively converts it back into light from the original scene. In other words, the purpose of gamma encoding is for recording the image — not for displaying the image. Fortunately this second step (the “display gamma”) is automatically performed by your monitor and video card. The following diagram illustrates how all of this fits together:

    RAW Camera Image is Saved as a JPEG File JPEG is Viewed on a Computer Monitor Net Effect
    image file gamma + display gamma = system gamma
    1. Image File Gamma 2. Display Gamma 3. System Gamma

    1. Depicts an image in the sRGB color space (which encodes using a gamma of approx. 1/2.2).
    2. Depicts a display gamma equal to the standard of 2.2

    1. Image Gamma. This is applied either by your camera or RAW development software whenever a captured image is converted into a standard JPEG or TIFF file. It redistributes native camera tonal levels into ones which are more perceptually uniform, thereby making the most efficient use of a given bit depth.

    2. Display Gamma. This refers to the net influence of your video card and display device, so it may in fact be comprised of several gammas. The main purpose of the display gamma is to compensate for a file’s gamma — thereby ensuring that the image isn’t unrealistically brightened when displayed on your screen. A higher display gamma results in a darker image with greater contrast.

    3. System Gamma. This represents the net effect of all gamma values that have been applied to an image, and is also referred to as the “viewing gamma.” For faithful reproduction of a scene, this should ideally be close to a straight line (gamma = 1.0). A straight line ensures that the input (the original scene) is the same as the output (the light displayed on your screen or in a print). However, the system gamma is sometimes set slightly greater than 1.0 in order to improve contrast. This can help compensate for limitations due to the dynamic range of a display device, or due to non-ideal viewing conditions and image flare.

    IMAGE FILE GAMMA

    The precise image gamma is usually specified by a color profile that is embedded within the file. Most image files use an encoding gamma of 1/2.2 (such as those using sRGB and Adobe RGB 1998 color), but the big exception is with RAW files, which use a linear gamma. However, RAW image viewers typically show these presuming a standard encoding gamma of 1/2.2, since they would otherwise appear too dark:

    linear RAWLinear RAW Image
    (image gamma = 1.0)
    gamma encoded sRGB imageGamma Encoded Image
    (image gamma = 1/2.2)

    If no color profile is embedded, then a standard gamma of 1/2.2 is usually assumed. Files without an embedded color profile typically include many PNG and GIF files, in addition to some JPEG images that were created using a “save for the web” setting.

    Technical Note on Camera Gamma. Most digital cameras record light linearly, so their gamma is assumed to be 1.0, but near the extreme shadows and highlights this may not hold true. In that case, the file gamma may represent a combination of the encoding gamma and the camera’s gamma. However, the camera’s gamma is usually negligible by comparison. Camera manufacturers might also apply subtle tonal curves, which can also impact a file’s gamma.

    DISPLAY GAMMA

    This is the gamma that you are controlling when you perform monitor calibration and adjust your contrast setting. Fortunately, the industry has converged on a standard display gamma of 2.2, so one doesn’t need to worry about the pros/cons of different values. Older macintosh computers used a display gamma of 1.8, which made non-mac images appear brighter relative to a typical PC, but this is no longer the case.

    Recall that the display gamma compensates for the image file’s gamma, and that the net result of this compensation is the system/overall gamma. For a standard gamma encoded image file (), changing the display gamma () will therefore have the following overall impact () on an image:

    gamma curves chart with a display gamma of 1.0
    Display Gamma 1.0 Gamma 1.0
    gamma curves chart with a display gamma of 1.8
    Display Gamma 1.8 Gamma 1.8
    gamma curves chart with a display gamma of 2.2
    Display Gamma 2.2 Gamma 2.2
    gamma curves chart with a display gamma of 4.0
    Display Gamma 4.0 Gamma 4.0

    Diagrams assume that your display has been calibrated to a standard gamma of 2.2.
    Recall from before that the image file gamma () plus the display gamma () equals the overall system gamma (). Also note how higher gamma values cause the red curve to bend downward.

    If you’re having trouble following the above charts, don’t despair! It’s a good idea to first have an understanding of how tonal curves impact image brightness and contrast. Otherwise you can just look at the portrait images for a qualitative understanding.

    How to interpret the charts. The first picture (far left) gets brightened substantially because the image gamma () is uncorrected by the display gamma (), resulting in an overall system gamma () that curves upward. In the second picture, the display gamma doesn’t fully correct for the image file gamma, resulting in an overall system gamma that still curves upward a little (and therefore still brightens the image slightly). In the third picture, the display gamma exactly corrects the image gamma, resulting in an overall linear system gamma. Finally, in the fourth picture the display gamma over-compensates for the image gamma, resulting in an overall system gamma that curves downward (thereby darkening the image).

    The overall display gamma is actually comprised of (i) the native monitor/LCD gamma and (ii) any gamma corrections applied within the display itself or by the video card. However, the effect of each is highly dependent on the type of display device.

    CRT Monitor LCD Monitor
    CRT Monitors LCD (Flat Panel) Monitors

    CRT Monitors. Due to an odd bit of engineering luck, the native gamma of a CRT is 2.5 — almost the inverse of our eyes. Values from a gamma-encoded file could therefore be sent straight to the screen and they would automatically be corrected and appear nearly OK. However, a small gamma correction of ~1/1.1 needs to be applied to achieve an overall display gamma of 2.2. This is usually already set by the manufacturer’s default settings, but can also be set during monitor calibration.

    LCD Monitors. LCD monitors weren’t so fortunate; ensuring an overall display gamma of 2.2 often requires substantial corrections, and they are also much less consistent than CRT’s. LCDs therefore require something called a look-up table (LUT) in order to ensure that input values are depicted using the intended display gamma (amongst other things). See the tutorial on monitor calibration: look-up tables for more on this topic.

    Technical Note: The display gamma can be a little confusing because this term is often used interchangeably with gamma correction, since it corrects for the file gamma. However, the values given for each are not always equivalent. Gamma correction is sometimes specified in terms of the encoding gamma that it aims to compensate for — not the actual gamma that is applied. For example, the actual gamma applied with a “gamma correction of 1.5” is often equal to 1/1.5, since a gamma of 1/1.5 cancels a gamma of 1.5 (1.5 * 1/1.5 = 1.0). A higher gamma correction value might therefore brighten the image (the opposite of a higher display gamma).

    OTHER NOTES & FURTHER READING

    Other important points and clarifications are listed below.

    • Dynamic Range. In addition to ensuring the efficient use of image data, gamma encoding also actually increases the recordable dynamic range for a given bit depth. Gamma can sometimes also help a display/printer manage its limited dynamic range (compared to the original scene) by improving image contrast.
    • Gamma Correction. The term “gamma correction” is really just a catch-all phrase for when gamma is applied to offset some other earlier gamma. One should therefore probably avoid using this term if the specific gamma type can be referred to instead.
    • Gamma Compression & Expansion. These terms refer to situations where the gamma being applied is less than or greater than one, respectively. A file gamma could therefore be considered gamma compression, whereas a display gamma could be considered gamma expansion.
    • Applicability. Strictly speaking, gamma refers to a tonal curve which follows a simple power law (where Vout = Vingamma), but it’s often used to describe other tonal curves. For example, the sRGB color space is actually linear at very low luminosity, but then follows a curve at higher luminosity values. Neither the curve nor the linear region follow a standard gamma power law, but the overall gamma is approximated as 2.2.
    • Is Gamma Required? No, linear gamma (RAW) images would still appear as our eyes saw them — but only if these images were shown on a linear gamma display. However, this would negate gamma’s ability to efficiently record tonal levels.

    For more on this topic, also visit the following tutorials:

    In gathering together all the information for a book in order to design and lay out the pages,
    you’ll usually be working with images – photographs and illustrations – scanned and saved at
    300dpi and saved in CMYK mode (see below).
    In this project you’ll look at managing colour within the pre-print process. The designer is the
    ‘bridge’ between the original manuscript and the printed product so it helps to have a good
    understanding of the colour management process involved prior to print production, so that you
    can manage your book project accordingly.
    Colour theory – RGB
    When you lay out your pages using DTP
    software, you work with digitised images,
    usually viewing your work via a computer
    monitor. Screens, TVs and monitors all work
    on the principle of transmitted white light,
    which is created from mixing Red, Green and
    Blue light. Therefore, we refer to this colour
    mode as ‘RGB’ or ‘additive colour’.
    CMYK
    It is important to be aware that although we are looking at a RGB colour monitor, and we
    perceive colours via this means, when it comes to printing we have to use physical pigment
    in the form of inks as opposed to light waves. The colour system used for printing is known as
    ‘subtractive colour’ or CMYK.
    Cyan, Magenta and Yellow, when mixed together, form a dull sort of brown, which isn’t quite
    black. So Black is added as a fourth colour and is represented here by the letter ‘K’. (This stands
    for ‘Key’ in printers’ terms rather than ‘B’, which may get confused with ‘Blue’.)
    Project Managing colour
    RGB additive colour
    A CMYK strip, often visible on newspaper margins – but without the identifying
    letters. These strips form part of the quality control process, enabling the print
    manager to see that all inks are running to correct capacity.
    Book Design 1 81
    Colour matching
    CMYK forms the colour-printing process for much printed material, and you need to be aware
    that the colours you’ll see on-screen will not be the same as the printouts you receive as ‘proofs’
    from the printer. Who hasn’t printed out something from their desktop printer and exclaimed
    ‘the colour’s nothing like that!’? When it comes to expensive print processes, you can’t afford
    unpleasant suprises in terms of colour reproduction; you have to be sure exactly how the colour
    is going to turn out. So you have to establish a way to calibrate your colours at the outset,
    so that you know exactly how any particular colour will turn out. One way of doing this is to
    work with CMYK sample books that printers provide. This enables you to specify exactly the
    proportions of Cyan, Magenta, Yellow and Black that are contained in any colour. You can then
    input these specifications into your DTP document and then rest assured that, although it may
    not look entirely right on-screen, it will match when you come to print it out because it is set up
    to the printer’s CMYK requirements, and not the computer’s inherent RGB mode.
    Pantone
    Another way of matching colour is to use a Pantone swatch book. Pantone is the trademark
    name for a range of ready-mixed inks, also sometimes known as ‘spot colours’. The Pantone
    range encompasses a wide range of colours, including metallic and pastels. Pantone Reference
    swatches can give both the Pantone ink number, plus the corresponding CMYK specification.
    Pantone ‘Solid to Process’ swatch book
    82 Book Design 1
    Halftone screens
    In order to print a continuous tone image
    – such as a photograph, illustration or
    artwork – using the CMYK four-colour
    printing process, the image has first to be
    converted from a continuous tone image
    to a series of lines. In order to facilitate
    this the image goes through a ‘halftone
    screening’ process – so that the colours
    within the photogaph can ultimately be
    reproduced by using the printing colours
    CMYK.
    The majority of printed photographs and artwork we see in books, newspapers and magazines
    are made up of many CMYK dots of varying sizes. These are printed via four screens, one for
    each of the print colours, set at different angles.
    The Black screen is set to 45 degrees, Magenta at 75°, 90° for Yellow and 105° for Cyan.
    You can see the evidence of this process when you look at a four-colour process (CMYK) printed
    photograph through a magnifiying lens or loupe. You’ll see clearly that the image is composed
    from those four inks, and it is their relative proximity, size and overlap that creates various
    colours and in this way re-presents continuous tone images. The size of the screen affects the
    quality of the image printed: the finer the screen, the better the image quality. Pictures printed
    on newsprint, for example, are printed via a relatively coarse screen, at 55lpi (lines per inch)
    whereas the images for books are printed using a higher grade screen, such as 170lpi. Within
    photo editing software there are options to adjust the settings for halftone screens, changing
    the shape and size of the dot elements.
    Moiré
    A moiré pattern occurs when screens are overlaid onto each other and the resulting image
    becomes distorted. The moiré effect is noticeable when the colours start to visually mix, in a
    swirly, jarring way. You can see it, for example, if you are watching someone on TV wearing a
    dogtooth jacket; the lines clash and this causes a visual interference.
    You need to be aware of moiré pattern when you scan images that have been printed once
    already, as they have already undergone a screening process. To offset this, you can apply the
    ‘Descreen’ option in photo editing software, and this removes the problem.