"I sent you the file and the blue came out purple!" almost always the cause is CMYK vs RGB.
Quick Summary
- Screens use RGB (Red, Green, Blue light)
- Printers use CMYK (Cyan, Magenta, Yellow, blacK inks)
- They render colour differently.
Technical (Simplified)
RGB is "additive" adding light to black. CMYK is "subtractive" adding ink to white paper. Some very bright RGB colours cannot be printed in CMYK.
Which Colours Shift Most?
- Bright reds → slightly more orange
- Electric blues → slightly more purple
- Neon greens → slightly more muted
- Fluorescent pinks/yellows → significantly duller
The Fix
Convert your file to CMYK before sending. Photoshop: Image → Mode → CMYK Color. Illustrator: File → Document Colour Mode → CMYK.
Pantone
For critical brand colours, specify a Pantone number.
Our Free Artwork Check
Every file sent to BPSD gets checked. If it's RGB, we flag it and show you the converted CMYK version.
Email your file or call 020 3669 9854.