WHY DO PRINTERS USE CMYK
Before I get into the technical explanation, I will first explain the basics that are good to know if you are involved in the printing and media industry.
- Most printers use CMYK (Cyan, Magenta, Yellow and Black) inks to produce all the other colours in the spectrum.
- Most electronic and digital screens emit RGB (Red, Green and Blue) light to produce the visible colour spectrum.
What this means for you is:
- If a document is intended for digital purposes, it should be created in RGB mode.
- If a document is intended for printing purposes, it should be created in CMYK mode.
- If you are using a digital photo for a print document, you should convert it from RGB to CMYK.
- When designing something intended for print, always do a test print to check the colours, as an RGB screen cannot correctly display the CMYK colour palette.
Now for the more technical explanation:
CMYK is used in colour printing and it actually describes the printing process itself. The CMYK printing process is known as subtractive colour mixing, rather than additive, which means that it begins with white and ends with black/darker colours. As you add colour, the result gets darker, this is important because paper is usually white/lighter colours. As mentioned, CMYK stands for Cyan, Magenta, Yellow and Black (or Key).
You should not think of CMY as actual colours. CMY in printing are films of ink that filter light and produce different colours. They are not used as specific colours but as filters that result in combinations of RGB light. K is used because combinations of CMY do not make good shades of greys or blacks and therefore K adds that.
The printing colour palette of CMYK is different to that used in digital devices. Devices such as television screens, and computer monitors use the RGB spectrum. This spectrum uses the Red, Green and Blue visible light spectrums to create the entire spectrum through the use of additive colour mixing.
Thus RGB works well for additive colours such as a monitor where RGB light is emitted. However printing combinations of RGB inks would just result in different shades of dirty browns and nothing of actual value. The RGB inks would filter out too much light and it would be useless.
And that is the reason CMYK is the hero of print.