Color rendering system CMY, color model CMYK - Informatics for the humanities

CMY color rendering system, CMYK color model

CMY (CMYK Cyan, Magenta, Yellow, Kontur or Key plate /Black, ie blue-green, magenta, yellow, outline/black) is a model opposite to RGB, which represents the colors of printing inks, photographic dyes and color toners. CMYK is called a model of subtractive primary colors (English Subtractive Primary Model) . Subtractive means subtracted, i.e. From white, primary colors are subtracted (Figure 7.6). The black color in this model is created by the full values ​​of all the primary colors (cyan, magenta and yellow).

CMY Color Model

Fig. 7.6. CMY Color Model

As the CMYK model is mainly used for color printing, and paper and other printed materials are surfaces that reflect light, it is more convenient to calculate how much light is reflected from a surface, rather than how much is absorbed. Thus, if we subtract three primary colors from RGB, RGB, we get a triple of additional CMY colors.

The CMYK model represents four colors that are used to reproduce full-color images (blue-green, magenta, yellow and black). In United States CMY colors are usually called blue, purple and yellow, although the first is more precisely called blue-green, and magenta is only part of the purple spectrum. The printing of the four colors corresponding to CMYK is also referred to as printing with triad paints.

For reference

Print using the CMYK model. The color in the printing process depends on the spectral characteristics of the dyes, their amount and viscosity, the method of their application, the characteristics of the paper and other factors. Theoretically, to reproduce the full range of colors, enough CMY inks - a color image in three colors, and blue, magenta and yellow dyes can recreate the full range of colors. However, when printing, this is impossible. CMY paints contain a few impurities, on different types of paper, when the ink is absorbed, different levels of brightness are obtained, which then affects the perception of color. As a result of mixing 100% levels of CMY paints, dirty gray with a tint is formed instead of black. To correct this situation, black paint is added, which compensates for the missing colors.

The value of K in the CMYK abbreviation. CMYK uses four colors, the first three in the abbreviation are named by the first letter of the color, and the fourth is black. The letter To (the key plate) is the key plate. In English-speaking countries, the key plate designates a black inkprint printed last on top of the previously printed three previous colors.

Another variant of the K value indicates a German origin ( To - from it < strong> Kontur ) . This version is also confirmed by the fact that many of the old installers call the corresponding film - a contour, a contour. In the technology of printing, black really makes a picture.

Reasons for using additional black pigment:

• In practice, due to the presence of impurities in dyes and errors in the proportions of components, the mixing of real cyan, magenta and yellow colors gives a rather dirty brown or dirty gray color;

• triadic colors do not give the depth and saturation that is achieved using the real black color;

• When drawing small black details of an image or text without using a black pigment, the risk of mismatching the points of application of magenta, cyan and yellow colors increases;

• mixing 100% of magenta, cyan and yellow pigments at one point substantially wet the paper, deform it and increase drying time, which makes it technically impossible to synthesize saturated black from three hundred percent components of the triad;

• Black pigment (which is usually used as soot) is significantly cheaper than the other three.

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