What is CMYK printing?
CMYK is also called printing color mode. The biggest difference between it and RGB is that RGB mode is a luminous color mode, and you can still see the content on the screen in a dark room.
CMYK is a color mode that relies on reflection. Why can we read the content of newspapers? It is because the sun or light shines on the newspaper and then reflects the content to our eyes. CMYK can only be seen under the condition of the external light source. So it cannot be read in a dark room. As long as the image seen on the printed matter is expressed in CMYK mode. For example, journals, magazines, newspapers, brochures, etc., all use CMYK mode.
CMY is the first letter of the names of three printing inks: Cyan, Magenta, and Yellow. K is the last letter of black, and K is used to avoid confusion with blue.
In theory, only three inks, CMY, are enough. Adding CMY together should get black. However, high-purity inks cannot be achieved for the time being, and the result of adding CMY is dark red. Therefore, in order to ensure the output of black, a special black ink needs to be added to blend.
What is RGB printing?
RGB is generally called the [three primary colors of color light], R (red), G (green), and B (blue). The color scale of RGB is 0-255. Since RGB is color light, the superposition of colors is brighter and brighter, so it is also called [additive color method]. When the three color values are 255, white will appear. Conversely, when the three RGB color values are all 0, it will become black. From the RGB color relationship diagram above, we can see that B+G is cyan, B+R is magenta, and G+R is yellow, which is complementary to CMYK colors.
What will happen if RGB is used for printing? Please check below contrast
You can see RGB on the Screen color, printed will show color tends to be fluorescent, CMYK on-screen color, printed will show color tends to be darker