Color printing is simply to copy image or text in color. What is the coloring principle of color printing?

1. Four color printing uses subtractive three primary colors (yellow, magenta, blue) and black for printing. The printing process that uses ink other than yellow, magenta, cyan and black to copy the original color is called "spot color printing" or "spot color printing". The method of full color reproduction is realized by using red, green, blue primary colors and black color materials (ink or fuel) according to the principle of subtractive mixing.

2. Primary color (CMYK, RGB)

a. CMY takes white as the background color subtraction, that is to say, CMY is all 0 is white, and all are 100% black (but in practice, due to the purity of ink and other issues, pure black can not be obtained, so introduce K) answer supplement

CMYK color mode is a printing mode. Four letters refer to cyan, magenta, yellow and black respectively, which represent four colors of ink in printing. In essence, CMYK mode is no different from RGB mode, but the principle of color generation is different. In RGB mode, the color light emitted by the light source is mixed to generate color. In CMYK mode, the color is generated by the light shining on the paper with different proportions of C, m, y and K inks. After part of the spectrum is absorbed, the light reflected to the human eye. As C, m, y and K are mixed to form color, with the increase of C, m, y and K, the light reflected to the human eye will be less and less, and the brightness of the light will be lower and lower. The method of generating color in all CMYK modes is also called color light subtraction.

b. RGB belongs to the three primary colors of color light. The principle of RGB is to realize the light source color by controlling the light. The light source peripherals are mainly displays, scanners, projectors, etc. Both CMYK and RGB belong to mixed and synthetic colors, which are all dependent on the color space of the device. RGB three primary colors are mixed in white, which is called additive mixing; CMYK three primary colors are mixed in black, which is called subtractive mixing.

3. Spot color

Spot color printing is based on different color requirements to prepare spot color ink. Some spot color inks contain four primary colors that cannot be obtained, such as silver, gold, fluorescent and some bright colors. Spot color printing ink is prepared according to the principle of color subtraction to obtain color. Its color lightness is low and saturation is high: spot color block with uniform ink color is usually printed on the spot, and the ink volume should be increased appropriately. When the thickness of the ink layer is large, the sensitivity of the change of the thickness of the ink layer to the color change will be reduced, so it is easier to get uniform and thick ink color The printing effect of.