Your design glowed on screen, then came back from the printer looking flat. Nothing went wrong — your screen speaks RGB and the press speaks CMYK, and they cannot say exactly the same colours. This guide explains the difference in plain English, shows which colours shift the most, and tells you exactly how to set up files so what you approve is what gets delivered.
Two different machines, two different languages
A screen makes colour with light: red, green and blue pixels that start black and add light to reach white. A printing press makes colour with ink: cyan, magenta, yellow and black laid onto white paper, each layer subtracting light. Additive versus subtractive is the whole story — light can be far more intense than reflected ink, so a screen can show colours no ink on paper can reproduce.
Which colours shift the most
Most colours translate fine. The heartbreakers are the ones only light can make:
- Neon and electric shades — lime green, hot pink, electric blue, bright orange. On press they come out noticeably duller.
- Vivid royal blues — RGB blue (0,0,255) prints as a muddy purple-navy unless rebuilt as a CMYK blue (around C100 M70 Y0 K0).
- Glowing reds — pure RGB red lands as a brick tone; build reds from magenta + yellow instead.
- Rich blacks — on screen every black looks the same; in print, 100% K alone looks grey-ish on large areas. Printers use a “rich black” mix (e.g. C60 M40 Y40 K100) for deep coverage.
How to set up files that print true
- Start the document in CMYK — InDesign, Illustrator and Affinity all ask at document setup. Canva exports: choose the PDF Print + CMYK option.
- Convert images before you judge them — in Photoshop: Image → Mode → CMYK Color (use the FOGRA39 / Coated FOGRA profile UK printers expect).
- Rebuild the danger colours — after converting, nudge blues toward C100 M70, rebuild reds from M+Y, accept that neon is a screen-only treat (or ask about spot/neon inks — some of the printers we compare offer them).
- Export a print-ready PDF — PDF/X-1a or “Press Quality”, 300dpi images, 3mm bleed, fonts embedded.
- Check the proof on the printer's terms — every printer in our comparison shows a proof or preflight; judge it knowing paper white is the brightest thing on the sheet.
Quick reference
| RGB | CMYK | |
|---|---|---|
| Made of | Red, green, blue light | Cyan, magenta, yellow, black ink |
| Lives on | Screens, web, apps | Paper, board, vinyl, fabric |
| White is | All light on | The paper itself |
| Black is | All light off | K ink (or rich black mix) |
| Gamut | Wider — neons possible | Narrower — neons dull down |
| Send to a printer? | They'll convert it (colours may shift) | Yes — what you see is what prints |
Every product in our comparison tables is printed CMYK unless the printer states otherwise, and all of them accept print-ready CMYK PDFs. Set up right, the price you compare is the only surprise-free part of print buying twice over.