CMYK stands for Cyan, Magenta, Yellow and Key (black). It is a color model used in printing where cyan, magenta, yellow and black inks are applied to paper to produce a full range of colors. CMYK is used for print projects rather than digital projects because it aligns with the subtractive color model used in printing.
What is the difference between CMYK and RGB?
RGB stands for Red, Green and Blue and is an additive color model used for digital displays like computer monitors and televisions. With RGB, the three colored lights blend together to create a wide range of colors. CMYK works in the opposite way – the inks absorb certain wavelengths of light and reflect others back to our eyes that we perceive as color.
Here are some key differences between CMYK and RGB:
- CMYK uses reflected light, RGB uses transmitted light
- CMYK has a smaller gamut (range) of colors than RGB
- RGB is device-dependent, meaning colors look different on each monitor
- CMYK is more consistent across different presses and inks
- RGB is additive (adding light), CMYK is subtractive (absorbing light)
In summary, CMYK is used for print projects and RGB is used for on-screen digital projects. When designing for both print and digital, RGB is often used initially and then converted to CMYK for the physical printing.
What do the CMYK letters stand for?
The letters in CMYK stand for the four ink colors used in the printing process:
- C – Cyan – A cool blue color
- M – Magenta – A reddish purple color
- Y – Yellow
- K – Key – Refers to the black key plate. Black is abbreviated as “K” to avoid confusion with Blue.
These are the four standard process colors used in offset printing, digital printing, and other printing methods. The percentages of each ink are mixed to create a full spectrum of colors.
How does CMYK printing work?
CMYK printing works by laying down overlapping dots of cyan, magenta, yellow and black ink on paper. The dots are spaced very closely together and blend optically when viewed from normal reading distance. Varying the dot size and overlap of the four inks allows a wide range of colors to be reproduced.
Here is a simplified overview of how CMYK printing works:
- The digital file separates colors into their CMYK build.
- Separations translate the color builds into the correct dot size for each ink.
- The four separations are transferred to printing plates.
- Ink is applied to the plates which are pressed against paper.
- The layered dots of ink create full color images.
This is an offset lithography process – the most common form of commercial printing. The separations can also be used with other printing methods such as digital printing and screen printing.
What is the CMYK color gamut?
The CMYK color gamut refers to the complete range of colors that can be reproduced using cyan, magenta, yellow and black inks. It is smaller than the RGB gamut for a few reasons:
- RGB light combines additively to create more colors
- Printed inks have impurities that limit their colors
- White paper reflects light and changes perception of ink
- Ink dots do not overlap perfectly or merge seamlessly
The CMYK gamut encompasses about 50% of visible colors based on typical printing. Some specialty CMYK systems with fluorescent inks and varnishes can expand the gamut but not to the full range of RGB displays.
Typical percentage of CMYK colors
There are no fixed CMYK percentages that produce specific colors. However, these are typical ranges:
| Color | Cyan | Magenta | Yellow | Black |
| Red | 0-20% | 90-100% | 90-100% | 0-20% |
| Green | 80-100% | 0-20% | 80-100% | 0-20% |
| Blue | 80-100% | 80-100% | 0-10% | 0-20% |
| Yellow | 0% | 0% | 100% | 0% |
| Black | 0% | 0% | 0% | 100% |
The percentages will vary based on the exact inks and paper used. But this gives a rough guide to typical amount of each ink used to produce primary colors.
When should CMYK be used vs RGB?
The general rule of thumb is:
- Use RGB for on-screen digital projects – websites, phone/tablet apps, digital ads, TV/video, etc.
- Use CMYK for printed projects – brochures, posters, stationery, packaging, magazines, books, etc.
RGB has a wider gamut suited for displaying color electronically. CMYK aligns with printing presses and will produce consistent printed colors.
For projects involving both print and digital, it is best practice to:
- Design initially in RGB for more color options
- Convert to CMYK when files are prepared for print
- Tweak colors after conversion to maximize gamut
- Use press proofs to finalize colors for printing
Some specific use cases where CMYK should be used instead of RGB:
- Sending artwork files to a commercial printing company
- Working with physical Pantone swatches and libraries
- Printing color mixes to evaluate on press
- Ordering printed color samples and prototypes
- Creating bitmap separations for screen printing
How to convert from RGB to CMYK
Converting artwork from RGB to CMYK can be done within design programs like Adobe InDesign, Photoshop and Illustrator. This involves going to the color settings and changing the document or image mode to CMYK.
When converting, some colors will shift noticeably while others remain close. This is due to the more limited CMYK gamut. Colors out of gamut will move to the closest reproducible shade. The brightness and saturation of some colors will also be reduced.
Tips for effective RGB to CMYK conversion:
- Avoid pure blacks – use rich blacks with multiple ink colors
- Reduce brightness of bright vivid colors
- Use color management settings that optimize for printing
- Add a cyan underbase to boost dark colors
- Consult Pantone books or swatches to find accurate CMYK mixes
For best print results, press proofs should be ordered and checked to finalize CMYK colors before the full print run.
The uses and benefits of CMYK
Here are some of the main advantages of using CMYK for print projects:
- Predictable and consistent colors – CMYK aligns with printing for reliable results across presses
- Standard for offset and digital printing – CMYK is supported by all professional print services
- Accurate Pantone matching – Pantone Connect has official CMYK mixes to specify spot colors
- Sharper quality – The rosette pattern used in CMYK printing minimizes misregistration of dots
- Works well with design programs – CMYK integrates smoothly into Adobe CC, Quark, CorelDRAW, etc.
Overall, for printed media, CMYK is the standard method of defining, specifying, and reproducing colors accurately and consistently.
Conclusion
CMYK is a subtractive color model using cyan, magenta, yellow and black inks to generate a wide range of colors. It is used primarily for print projects rather than digital due to its smaller gamut. CMYK allows reliable translation of colors from design to finished print. For optimal results, RGB is often used for initial designs which are converted to CMYK when print production begins.
