Color · Cyan, magenta, yellow, key (black)
CMYK color
Subtractive cyan, magenta, yellow and key (black) for print.
Key facts
| Channels | Cyan, magenta, yellow, key (black) |
|---|---|
| Range | 0%–100% per channel |
| Model | Subtractive |
| Naive conversion | K = 1 − max(R,G,B) |
| Exact conversion | Requires an ICC profile |
| Ink limit | Often 240%–300% total coverage |
Why the simple formula is not enough
The common RGB-to-CMYK formula subtracts the darkest channel and rescales the rest. It produces plausible numbers but ignores how particular inks and papers reflect light. A print shop's profile, ink limit and black generation strategy can change the result substantially.
Rich black and registration
Pure K black is economical and sharp for text. A “rich black” mixes cyan, magenta and yellow to make large dark areas look deeper, at the cost of ink and registration risk. Keep small text in K only, and respect the press's total ink limit.
Frequently asked questions
Why does my printed color look duller?
CMYK cannot reproduce every sRGB color, especially saturated greens and oranges. The printer converts to the nearest in-gamut value.
Can CMYK be converted back to RGB exactly?
Not without the profile and rendering intent used for the original conversion. Information is lost.
What is the K channel for?
Black ink. It improves density, sharpness and economy compared with mixing CMY to make black.