CMYK stands for Cyan, Magenta, Yellow, and Key (Black). These are the four primary colors used to create all other colors in physical printing systems on paper or any other physical medium. Therefore, the CMYK model is also known as four-color printing.
CMYK is a color mode used in printing, photography, and graphic arts to create documents intended for printing. It is a subtractive color mixture, meaning that combining cyan, magenta, and yellow on a white background results in black.
In other words, when you create a graphic piece (for example, a poster, flyer, business card, etc.) using software like Illustrator, Photoshop, Indesign, etc., you should always work in CMYK for your final art.
This is because CMYK is the color mode that printing machines need to apply the four-color inks. “Final art” (Arte Final in spanish) refers to the file that you send to the printer, which must be perfectly prepared to ensure the printed result matches the design created on the computer as closely as possible.
This includes color information, cut marks, etc.
Differences Between CMYK and RGB
In contrast to CMYK, there is the RGB color mode (additive), which is generated by computer screens and other devices.
Since RGB is an additive mixture and can display millions of colors, images in RGB often appear more realistic and vibrant than those in CMYK. This is because printing cannot achieve the same results as what is seen on screen.
There are converters to switch from CMYK to RGB and vice versa. There are also converters to switch from CMYK to Pantone (a single spot color mode) and vice versa. Common graphic design and vector programs typically allow these conversions to be made easily.
It’s important to note that there can sometimes be differences between what you see on screen and what you see in the final printed result during these color conversions. This is why it’s necessary to perform color proofs before conducting a large print run.
Moreover, the CMYK format, being a color mode oriented towards printing, can yield unexpected results. The outcome can vary significantly based on the quality of the printers, inks used, and the physical medium.
Why Black (Key) is Added in CMYK
In the CMYK model, although black can be achieved with the first three colors, a fourth black ink (Key) is added to provide intensity and precision to the printed result.
Even though cyan, magenta, and yellow can create black, in practice, achieving a pure black is rare due to less than 100% pigmentation.
Additionally, generating black in very small designs (such as text and fonts) by overlaying three colors can produce imprecise results.
Furthermore, on lightweight paper, the combined use of all three colors at 100% can overly saturate the paper and degrade the print quality.
What Other Color Spaces Exist?
Each printed medium, as well as each type of paper, reproduces printing inks slightly differently, even if they have the same CMYK values. Some absorb a lot of ink, others have a flat and glossy surface, and some are matte.
To address this, standard color profiles have been established to ensure consistent printing results for specific types of paper and printing inks. An example of such a color profile is the European printing industry’s standard color profile “ISO Coated v2.”
There are also color profiles for scanners and monitors to match colors across different technical devices, ensuring the highest color fidelity in the output medium. The data sets for standardizing color management systems are coordinated by the International Color Consortium (ICC).
Color systems go beyond this and define color composition differently and, in some cases, more broadly. Some are also based on other theoretical models of human color perception.
Pantone
The Pantone Matching System is an international color system used for graphics and printing, developed by the American company Pantone. It contains 1867 special colors (as of 2016), most of which cannot be reproduced with standard four-color printing.
CIELAB
The CIELAB color system, also known as CIELab* or Lab colors, is based on human perception of a so-called normal observer. This means it encompasses all perceptible colors and is not based on a mathematical model like RGB or CMYK.
The underlying standard is EN ISO 11664-4 “Colorimetry — Part 4: CIE 1976 Lab* Colour space.” In technical articles, you might often encounter the term “Tristimulus.”
RAL
The RAL Classics color system, established in 1927, includes 213 color tones. Since 1993, there has been the RAL Design system with 1625 standardized colors.
Some RAL colors are brand or signal colors for specific objects, such as RAL 3024 used for finishing fire and rescue vehicles, maritime rescue cruisers, and rescue boats of the DGzRS (German Maritime Search and Rescue Service).
The actual representation of RAL colors cannot be achieved through monitors or printers and can only be approximated using CMYK or RGB color indications.
HKS
The HKS color system is based on 88 basic colors and 3520 pure color tones that can be printed on both natural and artistic printing paper.
Unlike CMYK, these colors are pre-mixed before printing. The goal is the comparability and reproducibility of color tones. HKS colors can be simulated through CMYK, though their brightness is rarely matched.
