What Is Involved in a Four-Color Printing Process?

Four-color printing, using the subtractive three primary colors (yellow, magenta, cyan) and black for printing. If the printing process using yellow, magenta, cyan, and black inks to reproduce the original color is not called "four-color printing", it should be called "spot color printing" or "dot color" print".

Four-color printing is one of the types of printing. It is a method for color printing with four colors: yellow (Y), magenta (M), cyan (C) and black (BK). In theory, four-color printing can obtain thousands of colors in four colors of Y, M, C and BK without repeating. Single colorY, M, C and BK four types; dual colorY + M, Y + C, Y + BK, M + C, M + BK, C + BK; three colorsY + M + C, M + C + BK, Y + C + BK, Y + M + BK; four colors-one type of Y + M + C + BK, a total of fifteen colors. In color printing, the size of the "dot" is used to indicate the depth of the color. In theory, the "dot" can be divided into 22 levels. According to the combination formula C _m · g, C ¹ ₄ · 22 ¹ can be obtained. + C ² ₄ · 22 ² + C ³ ₄ · 22 ³ + C ⁴ ₄ · 22 ⁴ = 279840 (species) color.

In fact, due to the deformation error of the "dot dots" in the printing process and the limitation of the visual recognition threshold, the four-color printing can obtain much less colors than theoretically ^[1]

The four-color printing process involves the use of four-color screen angles and four-color inks (three subtractive primary colors: cyan, magenta, yellow, and black) to reproduce the colors on the original. It can also be called process printing (CMYK printing) or CMYK printing (CMYK printing), which is a term named after printing ink.

Print color pictures in three subtractive primary colors (yellow, magenta, and cyan) and black. The color image of the original used for printing must be separated into its own color separation sheet, and a black separation plate is added to correct the cyan, magenta, and yellow inks to improve the blackness of the printed image. These films are used to make the four plates required for four-color printing.

On a printing press, each printing plate must be accurately registered with other printing plates in order to obtain high-quality results, which is the industry standard printing method. CMYK is a color system widely used in computer printing equipment ^[2]

Due to the limitations of colorants and production processes, the C, M, Y, and K primary color inks used in four-color printing have a large gap between the spectral curve of the color development and the ideal color spectral curve. Ink overprint

The printing color is composed of a color component and a neutral gray component. Under the condition of limiting the amount of printing ink used, if the neutral gray component is excessive, it will not only cause a large distortion of the brightness characteristics of the printed image, but also relatively reduce the amount of color component, causing Color saturation decreases. The visual lightness of the four-color printing color is approximately straight, showing that the neutral gray component of the printing color is too much. Four-color printing emphasizes increasing the saturation of copied colors, at the expense of excessive color brightness, which is another important drawback of four-color printing technology. Compared with the colors of natural sceneries, due to the above defects, the four-color printing reproduces heavy colors, has large distortion of the tone, has unrealistic layering, and is not strong in three-dimensionality.

What is printing color sequence

The so-called printing color sequence refers to the sequence of overprinting of each color printing plate with single color as a unit in multi-color printing. The yellow, magenta, cyan, and black printing color sequence is used in the traditional printing process because the yellow ink was the most opaque and had strong hiding power. Therefore, the yellow ink had to be printed first, otherwise the overprinting color would be very large. influences. Now this traditional method of color sequence arrangement has been gradually phased out, because the yellow ink produced now has better transparency, which reduces its influence on the overprint color, and also makes the printer reconsider the traditional printing color sequence arrangement. The field density is used as a means to control color, dot increase, and ink overprint on a four-color machine, so the new cyan, magenta, yellow, and black (or black, cyan, magenta, and yellow order) have become the commonly used color order. ^[3]

The four-color printing of maps was proposed in the 1990s, and it is many years behind the conventional four-color printing reproduction color printing. According to the basic principle of color subtractive method, the use of three colors of yellow, magenta and cyan should be able to allocate any color other than white. In this sense, multi-color maps can also be copied using four-color printing. Because of the complexity and particularity of the content expressed on the map, the particularity of the colors used in the map has been determined. In addition, there are still many shortcomings in printing equipment and materials in history. Therefore, the four-color printing of maps has been in a relatively long period It is just an issue to be discussed but it has been unable to achieve it in production practice ^[4] .