CMYK vs RGB: The Mistake 90% of Designers Still Make

The big RGB vs CMYK confusion

Your screen displays in RGB (Red, Green, Blue). The printer prints in CMYK (Cyan, Magenta, Yellow, Black). Same universe? No. Two completely different worlds.

RGB: The world of light

RGB is additive: the more light you add, the brighter it gets. White = RGB(255,255,255). Black = RGB(0,0,0).

It's used for:

• Screens (phones, TVs, monitors)
• The web and social media
• Video

CMYK: The world of ink

CMYK is subtractive: you remove color starting from white. The more ink you add, the darker it gets. White = CMYK(0,0,0,0). Black = CMYK(0,0,0,100).

It's used for:

• Offset printing
• Gravure
• Flexography

The problem

The RGB gamut is LARGER than the CMYK gamut. That means: there are colors your screen can display in RGB that a printer CANNOT print in CMYK.

Example: a vivid blue on your screen. Convert it to CMYK for printing, and that blue turns dull. Guaranteed disappointment.

How to avoid the problem

Option 1 (Recommended): Work in CMYK from the start

Open your software (InDesign, Photoshop) in CMYK mode. You see exactly what the printer will print. No surprises.

Option 2: Work in RGB and convert intelligently

Work in RGB, then when exporting for print, convert to CMYK with a "Perceptual" rendering intent (PreserveColorIntent). This compresses colors in a logical way.

What about PrintCheck?

PrintCheck automatically detects:

• RGB colors in a print file? ⚠️ Alert
• Out-of-gamut colors (impossible to print)? ⚠️ Alert
• Correct CMYK conversion? ✓ Ok

Simple rule

RGB = screen. CMYK = print. Don't mix them. PrintCheck will tell you if you get it wrong.