How to deal with color reproduction in the hottest

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How to deal with the neutral gray balance in color reproduction in printing reproduction

I. The concept of neutral gray balance

the reproduction of printed matter is color restoration, tone restoration, texture restoration and clarity restoration. The so-called tone is that colors are classified according to lightness. Colors are three variables. Neutral gray is a three-dimensional color space. Neutral gray is composed of three colors y, m, and C. The three variables of color (hue, saturation, and external protective lightness of the testing machine) hv/c are represented, while neutral gray has no hue, saturation, and only one-dimensional variable lightness

we know that the primary colors R, G and B of color and light transition to the white field, while the primary colors y, m and C of pigment transition to the black field. In addition, four-color printing is limited by two conditions: first, only y, m, C and K inks can be used; Second, the ink layer on each paper is evenly distributed

neutral grey refers to a series of colors such as y, m and C, which absorb the same amount of R, G and B light, with only the change of lightness but no change of hue and chromaticity

when the three primary colors y, m and C of the pigment can be completely copied out of the neutral gray ladder after being overprinted on the spot or at an appropriate proportion, then the three primary colors y, m and C are said to have reached the neutral gray balance. The monochromatic density of three primary colors to obtain gray balance is called equivalent neutral gray density

II. Emphasize the significance of neutral gray balance

1 Copy the gray of the original correctly

2. In plate making and printing, neutral gray balance is used as a measure of whether the proportion of three primary colors of ink is appropriate in color separation plate making and printing

III. background color removal and neutral gray balance

1 The concept of background color removal. The so-called base color removal (UCR) refers to the removal of a part of the base color of the production line from the three primary colors y, m and C, which is being finally debugged and optimized into neutral gray before the formal production, that is, the base color that is approximately black formed by the superposition of the three primary colors y, m and C of the pigment, and is replaced by black ink

for example, suppose that a certain color is overprinted by Y, m and C, and the area of Y point is 80%, the area of m point is 80%, and the area of C point is 100% (on the spot). If 80% Y and 80% m energy and 90% C overlap according to the neutral gray balance, it can form black ink equivalent to 90% advanced high molecular materials as the largest field point area with the highest output value at present, then:

C = 80% y + 80% m + 100% C = 80% y + 80% m + 90% C + 10% C = 90% K + 10% C

2 The necessity of background color removal

① improved printability: generally, it is used in dark tone. If the three primary colors y, m and C are used in the dark tone area, the dot area is often very high, and it is easy to produce process problems in high-speed multicolor printing. If the background color is removed, the ink amount is greatly reduced and the printability is improved

The silage stretch film with the same performance can be made with 19 micro; M instead of 25 micro; The thickness of M is produced - the thickness is reduced by 30%

② it is conducive to controlling the neutral gray balance during printing

③ it is conducive to the drying of ink and reduces the overprint of Y, m and C primary color ink

④ because the consumption of Y, m and C color inks is reduced and the consumption of black inks is increased, the cost is reduced, and the price of black inks is relatively cheap

⑤ after adopting the high-speed multi-color printing machine, the biggest problem affecting the speed and quality improvement of the high-speed printing machine is the ink drying problem, that is, the speed of ink drying will directly affect the speed and product quality improvement of the high-speed multi-color printing machine. There are many ways to solve this problem, such as changing the composition and structure of the ink, improving the drying method of the printing machine, and improving the process, increasing the concentration and gloss of the black ink, reducing the amount of Y, m, C primary color ink in the non color part, and effectively thinning the ink layer to speed up the drying speed, which is the fundamental reason for using UCR in color reproduction

3. Some points that should be paid attention to when removing the background color

① background color removal generally works in neutral gray and near neutral gray areas of middle tone and dark tone

② correctly control the removal amount

③ master the control of removal point, that is, the range of removal control

IV. The relationship between the dark line of the black version and the removal amount of the background color

the depth of the black version and the removal amount of the background color are closely related. The removal amount of the background color is large, and the black version should be deep; On the contrary, the background color removal is less, and the black version should be light. At the same time, the length of the black version tone should be determined according to the length of the dark tone density range of the original. If the dark density range is long, the black version should be long, and if the dark density range is short, the black version should be short. Neutral gray balance is an important condition for color reproduction and restoration of originals, and it is also a difficult technology to master in plate making and printing, because it is difficult for y, m, C three color inks to reproduce neutral gray balance

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