Skip to content

Why do printers use CMYK color mode?

Python Tutorials


 There are a number of color modes that can be used to create colors on different mediums such as screens, monitors, paper, whiteboard, projectors, walls, painting canvas, smart watches, water and even sky.

Some of these color modes are: RGB, LAB, CMYK, P, YCbCr and HSV. If you’re interested we have an article about all the color modes and why they exist.

But why is it CMYK which is used predominantly for tasks paper related tasks such as printing.
Here is a closer look at why most printers use CMYK color mode and CMYK cartridges to compose color during printing.

Understanding why CMYK is more suitable for printing requires a understanding of some color theory.

What is CMYK?

CMYK, stands for Cyan, Magenta, Yellow and Key is another way of mixing colors but since Cyan, Magenta and Yellow are much brighter to begin with it becomes way more convenient to create darker colors such as red green and blue with them on paper compared to the other way around which is creating cyan, magenta and yellow by mixing red, green and blue.

K in CMYK stands for key color which is black. This is because CMY is not sufficient to create a dark black.

Should you convert digital images to CMYK?

Modern day printers will make the conversion for you so for most people separately converting all images to CMYK before printing is, thankfully, unneccessary.

However, there can be many cases where you might want to still make this conversion for printing work if you’re serious about the colors of your print output.


CMYK is subtractive coloring it uses reflection on paper or canvas or nature to reflect some of the colors to produce colors while other wavelengths (colors) are absorbed.

Primary colors are RGB, these are primary because we get them directly from the light source.

Secondary colors are CMY, these are secondary because we get them by subtracting them from a combination of light (which is RGB).

This is why we don’t see different colors from sunlight like rainbow although it contains all colors, at least when there isn’t rain to bend some of the wavelenghts. They mix perfectly in the air.

CMY - RGB colors


Paper vs Light

It’s a matter of material on which color is being produced. As you probably know monitors, projectors, TVs, mobile phones etc. all use some technology of lighting to light up their pixels. All these electronic devices also use RGB as it is a convenient standard on electronic display monitors and screens.

However, mixing physical ink coming from cartridge and creating different colors on paper understandably is not the same thing. One doesn’t have the luxury to reduce the light from the source by adjusting the strength of a color channel. You just add colors together and that’s it.

As it turns out, without the freedom of light adjustment it becomes pretty difficult to get all shades of colors on paper with red, green and blue. But particularly getting lighter shades of colors becomes very difficult.

In short, mixing RGB, which exist in direct light source, via light, is not the same as attempting to mix RGB on paper. In fact it’s impossible to have true primary colors on paper because they will always be reflected on paper and not be coming from the direct light source.

This is also the reason why photos or paintings are never as impressive as the real thing such as an event like sunrise or sunset or the stars. That doesn’t mean a painting can’t be incredibly impressive because of the technique used or artist’s expertise in making different colors pop.

Starting with secondary colors to begin with

It’s a smart idea to begin with the lighter secondary colors cyan, magenta and yellow and then produce red, green and blue using them when needed.

This is the main reason why CMYK color mode is the standard for printing technology.

Multiple white printers next to white monitor

Color combinations

While rgb colors can produce cmy, it turns out you can also produce rgb colors just by adding cmy colors back.

One main difference is, when you add red, green and blue together you ideally get perfect white. But, when you add cyan, magenta and yellow together you get black.

In summary:

magenta + yellow = red

cyan + yellow = green

cyan + magenta = blue

cyan + magenta + yellow = black

Or the other way around:

blue + green = cyan

blue + red = magenta

green + red = yellow

cyan + magenta = white

CMY - RGB colors

Key in CMYK

So, if adding all cmy components together gives black, why is key component which stands for black needed?

The main reason is that adding cyan, magenta and yellow doesn’t actually produce a perfect dark black but rather a light black or dark gray color. So, having an extra K channel means covering all ranges of the color scale better.

Another advantage of this is that black color is used much more than other colors in general especially in printing where lots of text is usually involved. Having a separate black cartridge helps balance out the usage differences between colors.


In this Python Tutorial, we’ve learned fundamentals of different color modes and we’we discussed the advantages of CMYK color mode.

We have also tried to shed light on the CMYK color standard from the printing perspective.