CMYK vs RGB for print: what actually happens on press
Every designer has had the moment: the proof comes back from the printer and the red is wrong. It's not the red you picked. It's shifted toward orange, or it's muddy, or it's just... off. The blues look purple. The greens are dull. What happened?
What happened is a color space conversion you didn't control.
RGB is light. CMYK is ink.
Your monitor creates color by mixing red, green, and blue light. A printing press creates color by mixing cyan, magenta, yellow, and black ink. These are fundamentally different physical processes, and they can't reproduce the same range of colors.
RGB can display colors that CMYK physically cannot print. Neon green, electric blue, vivid orange — these exist in RGB's color gamut but fall outside what ink on paper can produce. When these colors get converted to CMYK, the software finds the closest printable match. That match is always duller, always shifted.
The specific shifts you'll see
- Bright reds shift toward orange or brick.
- Electric blues shift toward purple.
- Vivid greens lose saturation and look muted.
- Neon colors become dull pastels.
- Pure black (0,0,0 in RGB) may appear as a dark gray unless converted to rich black (a mix of all four CMYK inks).
These shifts aren't bugs. They're physics. The question is whether you control the conversion or the printer's automated system does it for you.
Color profiles: the translation table
A color profile is a translation table between a color space and a specific output device. When you convert from RGB to CMYK, the profile determines exactly how each color maps.
The most common profiles for commercial print:
- FOGRA39 — standard for coated paper in Europe. The most common EU profile.
- FOGRA47 — uncoated paper in Europe.
- GRACoL — standard for coated paper in North America.
- SWOP — web offset printing in North America.
- ISO Coated v2 — an ISO standard that overlaps with FOGRA39.
Your printer will tell you which profile to use. If they don't, ask. If they can't answer, use FOGRA39 (EU) or GRACoL (US) as a safe default for coated stock.
How to convert in your design tool
InDesign
File → Export → PDF (Print) → use a PDF/X-4 preset. In the Output tab, set Color Conversion to "Convert to Destination" and pick your printer's profile. This converts at export time so you can preview the result.
Illustrator
File → Document Color Mode → CMYK Color. This converts the working document. Then File → Save As → PDF → PDF/X-4 preset. Check Output → Color Conversion: "Convert to Destination (Preserve Numbers)".
Figma
Figma works in RGB only — there's no CMYK mode. Export your frame as PDF, then open in Acrobat Pro → Print Production → Convert Colors → pick your CMYK profile. This is a two-step process and there's no way around it in Figma.
Canva
Canva Pro: Share → Download → PDF Print → check "CMYK". Canva Free exports RGB only. If you're on the free plan, you'll need to convert in Acrobat like the Figma workflow.
How PrintPress helps
PrintPress checks every page of your PDF for RGB elements. If your file is RGB, the report tells you — with the specific pages affected and the profile your printer requires (if you uploaded their spec sheet). The fix steps are tailored to the tool you used to create the file.