Color printing or color printing is the image or color text reproduction (as opposed to simpler black & white or monochrome printing). Each natural scene or color photograph can be optically and physiologically dissected into three primary colors, red, green and blue, an amount more or less the same that gives rise to white perception, and different proportions that give rise to the visual sensation of all others. color. The combination of additives of two primary colors in approximately equal proportions raises the perception of secondary color. For example, red and green yellow, red and blue produce magenta (purple), and green and blue produce cyan (turquoise). Only yellow is counter-intuitive. Yellow, cyan and magenta are only "basic" secondary colors: an unequal mixture of the primary raises the perception of many other colors that can all be considered "tertiary."
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While there are many techniques for reproducing color images, special graphics processes and industrial equipment are used for massive color image reproduction on paper. In this sense, "color printing" involves reproduction techniques that are suitable for printers capable of generating thousands or millions of impressions for publishing similar newspapers and magazines, brochures, cards, posters and similar mass market items. In this type of industrial or commercial printing, the techniques used to print colorful images, such as color photos, are referred to as the four-color process or just the printing process. Four inks are used: three secondary colors plus black. The ink colors are cyan, magenta, yellow and key (black); abbreviated as CMYK. Cyan can be regarded as minus-red, magenta as minus-green, and yellow as minus-blue. This ink is semi-transparent or translucent. Where the two inks overlap on paper because the printing impression is in sequence, the main color is felt. For example, yellow (minus-blue) overprinted by magenta (minus green) produces a red color. Where all three inks can overlap, almost all light is absorbed or reduced, resulting in almost black, but in practical terms it is better and cheaper to use separate black ink instead of combining three colored inks. The secondary or subtractive colors of cyan, magenta and yellow can be considered "prime" by printers and watercolors (basic inks and transparent paints).
Two graphical techniques are required to prepare an image for four color printing. In the "pre-press" phase, the original image is translated into forms that can be used on the printing press, through "color separation," and "filtering" or "halftoning." These steps enable the creation of print plates that can transfer color impressions to paper on a printing press based on lithography principles.
The emerging color printing method is the six-color process printing (for example, the Pantone Hexachrome system) that adds orange and green to traditional CMYK inks for larger and more vibrant gametes, or color ranges. However, the alternative color system still relies on color separation, halftoning and lithography to produce printed images.
Color printing can also involve at least one color ink, or some color ink that is not the primary color. Using a limited amount of color ink, or a particular color ink other than the main color, is referred to as "point dye" printing. Generally, spot-color inks are special formulations designed to be printed on their own, rather than mixed with other inks on paper to produce different colors and shades. The range of spot color inks that are available, such as paint, is almost unlimited, and much more varied than the colors that can be produced by four-color printing. Spot-color inks range from fine pastels to intense fluorescent to reflective metals.
Color printing involves a series of steps, or transformations, to produce quality color reproduction. The following sections focus on the steps used when reproducing color images in CMYK printing, along with several historical perspectives.
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Color printing history
Woodblock printing on textiles precedes printing on paper in both East Asia and Europe, and the use of different blocks to produce color patterns is common. The earliest way to add color to the items printed on paper is by hand coloring, and it is widely used for printed drawings in Europe and East Asia. Chinese wood pieces have this at least from the 13th century, and which originated in Europe soon after its introduction in the 15th century, where it continued to be practiced, sometimes at a highly skilled level, until the 19th century - elements the official British Ordnance Survey chart was hand-painted by boys until 1875. Early European printed books often leave room for initials, rubrics and other elements to be added by hand, as already in the manuscript, and some books Early prints have complex limits and miniatures are added. However this becomes less frequent after about 1500.
East Asia
China
The English art historian Michael Sullivan writes that "the earliest color printing known in China, and indeed worldwide, is a two-color image on a Buddhist silk scroll, dated 1346". Color prints were also used later in the Ming Dynasty. In Chinese blocking of woods, early color woodcuts mostly appear in fancy books about art, especially the more prestigious painting media. The first known example is a book about ink cakes printed in 1606, and color techniques culminate in books about paintings published in the seventeenth century. Notable examples are the Ming-era Chinese painter Hu Zhengyan The Treatise on Painting and Writing of Ten Bamboo Studios in 1633, and Manual Mustard Seed Garden published in 1679 and 1701, and printed in five colors.
Japanese
In Japan, the color of wood pieces is used for sheet printing and book illustrations, although this technique is better known in the history of prints. The "colorful" technique, called nishiki-e in its fully developed form, spreads rapidly, and is widely used for sheet moldings from the 1760s. The text is almost always monochrome, and many books continue to be published with monotomous illustrations sumizuri-e, but the growing popularity of ukiyo-e brings demand for more colors and technical complexity. In the nineteenth century most artists designed prints to be published in color. The main stages of this development are:
- Sumizuri-e (????, "ink printed image") - monochrome printing using only black ink
- Tan-e (??) - monochrome sumizuri-e prints by handcoloring; distinguished by using orange highlights using a red pigment called tan
- "Beni-e" (??, "red picture") - monochrome sumizuri-e prints by handcoloring; distinguished by using red ink detail or highlight. Do not be confused with "benizuri-e", below.
- Urushi-e (??) - a method in which glue is used to thicken ink, clarify the image; gold, mica and other substances are often used to enhance the image further. This technique is often used in combination with hand coloring. Urushi-e can also refer to paintings using lacquer instead of paint; It is very rarely used on molds.
- Benizuri-e (????, "red printed image") - images are printed in two or three colors, usually containing red and green pigments, and black ink. This printing technique should not be confused with "beni-e", above. Both "beni-e" and "benizuri-e" are so named because the dominant color is reddish, derived from safflower plant dyes (beni?).
- Nishiki-e (??, "brocade pictures") - a method in which multiple blocks are used for separate parts of the image, allowing a number of colors to be used to achieve very complex and detailed images; Separate blocks will be carved to apply only to parts of images intended for one color. Registration mark called kent? (??) is used to ensure correspondence between applications of each block.
Further developments are followed from refinement of techniques and trends in taste. Example:
- Aizuri-e (????, "indigo print image"), Murasaki-e (??, "purple image"), and another style in which one color will be used instead of, or not, black ink. This is a special technique that was increasingly popular in the nineteenth century, although some examples can be seen earlier.
Europe
Most of the early methods of color printing involve multiple prints, one for each color, although there are different ways of printing two colors if they are separate. Liturgical liturgis and many other types require rubrics, usually printed in red; this has long been done by a separate print run with red forme for each page. Another method is used for single leaf molding. Chiaroscuro cutting is a European method developed in the early 16th century, where to normal logging blocks with linear images ("line blocks"), one or more "tone block" colors printed in different colors will be added. This is a method developed in Germany; in Italy only tone blocks are often used, to create more effects like a sweeping image. Jacob Christoph Le Blon developed a method using three intaglio plates, usually in mezzotint; this is printed redundant to achieve a variety of colors.
In the 19th century a number of different color printing methods, using wood (technically Chromoxylography) and other methods, were developed in Europe, which for the first time achieved widespread commercial success, so that in the following decades the average home may contain many for example, both are dependent as prints and as book illustrations. George Baxter patented in 1835 a method of using intaglio line plates (or sometimes lithographs), printed in black or dark, and then overprinted to twenty different colors of logs. Edmund Evans uses help and wood throughout, with up to eleven different colors, and lastly specialized in illustrations for children's books, using fewer blocks but overprinting non-solid color areas to achieve mixed colors. British artists such as Randolph Caldecott, Walter Crane, and Kate Greenaway are influenced by Japanese molds that are now available and fashionable in Europe to create an appropriate style, with a flat color field.
Chromolithography is another process, which by the end of the nineteenth century has become dominant, although it uses many prints with stones for each color. Mechanical color separation, initially using photographs of images taken with three different color filters, reduces the number of prints required by up to three. Zincography, with zinc plates, then replaced lithographic stones, and remained the most common color printing method until the 1930s.
Modern processes
Color separation process
Usually color separation is the responsibility of color separator. This includes cleaning up files to be ready for printing and making evidence for the prepress approval process. The process of color separation begins by separating the original artwork into red, green, and blue components (eg by digital scanners). Before digital imaging was developed, the traditional method of doing this was to capture images three times, using filters for each color. However this is achieved, the desired result is three grayscale images, representing the red, green, and blue (RGB) components of the original image.
The next step is to reverse each of these separations. When a negative image of the red component is generated, the resulting image represents the cyan component of the image. Similarly, negatives are produced from green and blue components to produce magenta and yellow separations, respectively. This is done because cyan, magenta, and yellow are subtractive primaries that each represent two of the three primitive additives (RGB) after one primer additive has been subtracted from white light.
Cyan, magenta, and yellow are the three basic colors used for color reproduction. When these three colors are widely used in printing, the result should be a reasonable reproduction of the original, but in practice this is not the case. Due to ink limitations, darker colors become dirty and muddy. To counter this, black separation is also created, which enhances the image's shadow and contrast. There are many techniques for getting this black separation from the original image; this includes replacement of gray components, under color removal, and under color additions. This printing technique is referred to as CMYK ("K" stands for key , the traditional word for black plates).
Current digital printing methods do not have a single color space limit that traditional CMYK processes do. Many presses can print from a torn file with an image using RGB or CMYK mode. The ability of color reproduction of a particular color space may vary; the process of getting an accurate color in the color model is called color matching.
Screening
The ink used in color printing machines is semi-transparent and can be printed on top of each other to produce different colors. For example, green results from printing yellow ink and cyan on top of each other. However, the printing press can not vary the amount of ink applied to a particular image area except through "filtering," a process that represents lighter shades as a small dot instead of a dense, ink area. This is analogous to mixing white paint into colors to make it brighter, except for white is the paper itself. In a process colored print, the screened image, or halftone for each ink color is printed in a row. The lattice screen is set at different angles, and therefore the point of creating a small rose, which, through a kind of optical illusion, appears to form a continuous tone image. You can see halftoning, which allows printed images, by checking images printed under magnification.
Traditionally, halftone screens are generated by ink lines on two sheets of cemented glass at the right angle. Each color separation film is then exposed through this screen. The resulting high contrast image, once processed, has dots of varying diameter depending on the amount of exposure the area receives, which is modulated by the grayscale film separation image.
The glass screen is made obsolete by high contrast films where the halftone dots are exposed to the separation film. This in turn is replaced by a process in which halftones are produced electronically directly on a film with a laser. Recently, computer technology to the plate (CTP) has enabled the printer to cut the film part of the whole process. CTP images of the dots directly on the plate with laser printing, save money, and eliminate the film step. The number of lost generations in printing negative lithographs to lithographic plates, unless the processing procedure is completely ignored, is almost completely ignored, since there is no dynamic range loss, no density gradation, nor color, or large dye. silver grains to compete in ultra-negative fast access is very slow.
Screens with "frequencies" of 60 to 120 lines per inch (lpi) reproduce color photos in newspapers. The rougher the screen (lower frequency), the lower the quality of the printed image. Very high absorbent paper requires a lower screen frequency than the stock of absorber-coated paper used in magazines and books, where the screen frequencies of 133 to 200 lpi and higher are used.
The size of how many ink spots spread and become larger on paper is called dot gain. This phenomenon must be taken into account in the photographic or digital preparation of the screened image. Dot gain is higher in paper stocks that are more absorbent and not coated like newspaper.
See also
- Block printing
- Flexibility
- Letterpress printing
- Print offset
- Rotogravure
- Typography
References
Note
- Bruno, Michael H. (Ed.) (1995). Pocket Pal: Graphic Arts Production Handbook (16th ed.). Memphis: International Paper
- Gascoigne, Bamber. How to Identify Prints: A Complete Guide to Manual and Mechanical Processes from Woodcut to Inkjet , 1986 (2nd Edition, 2004), Thames & amp; Hudson, ISBN 0-500-23454-X
- Hunt, R.W.G., Color Reproduction (1957, 1961, 1967, 1975) ISBNÃ, 0-85242-356-X
- Yule, John A.C., Color Reproduction Principle (1967, 2000) ISBNÃ, 0-88362-222-X
- Morovic, J., Color Gamut Mapping (2008) ISBNÃ, 978-0-470-03032-5
Further reading
- Bruno, Michael H. (Ed.) (October 2000). Pocket Pal: Graphic Art Production Handbook Technical Graphic Art Fndtn; 18th Edition, ISBNÃ, 0-88362-338-2
- Hardie, Martin, Colored Books (1906, reprinted 1990)
- Gascoigne, Bamber, Milestones in Color Printing 1457-1859 (Cambridge UP, 1997)
- Also various articles in the Journal of the Printing Historical Society - see: http://www.printinghistoricalsociety.org.uk/journal_indices/index.html
Source of the article : Wikipedia
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