Print & production
RGB vs CMYK color modes
A design can look brilliant on your screen and dull on paper, and the reason is almost always color mode. This page explains what the document Color mode setting actually changes, how to switch to CMYK (print), and how to read the warnings that keep your colors honest.
Why the mode matters
Screens and presses build color in opposite directions. A monitor mixes red, green and blue light — start from black and add light to reach white. This is additive color, and it can produce vivid, glowing hues.
A press does the reverse. It lays down cyan, magenta, yellow and black ink on white paper, and each layer of ink subtracts light that would otherwise bounce back to your eye. This is subtractive color, and its range is narrower than a screen's — which is exactly why some on-screen colors simply cannot be printed.
The color mode is how Popcorn Editor knows which of these two worlds you are targeting, so it can preview and warn you accordingly.
Where the setting lives
Open the View menu and choose Color mode. You'll see two options:
- RGB (screen) — hint: "RGB — best for screen, web and social."
- CMYK (print) — hint: "CMYK — for print. Colors are stored as ink values and soft-proofed on screen."
The same switch is available in the Properties panel when nothing is selected, alongside the other document-level settings. The choice is saved with your document.
What CMYK mode changes
When you switch to CMYK (print), each color is stored as ink values — the amounts of cyan, magenta, yellow and black that make it up. Those ink values become the source of truth for the file.
What you see on the canvas is an on-screen soft-proof: an approximate simulation of how those inks will look once printed. You still pick and edit colors in the familiar color picker, but behind the scenes the document is now describing ink, not light. Switch to CMYK before you start choosing colors and the soft-proof guides you from the very first swatch, instead of shifting your palette after the fact.
Reading the soft-proof
A soft-proof is a helpful simulation, not a guarantee. How close it looks to the printed result depends on things Popcorn Editor can't see: your monitor's calibration, the ambient light in the room, and the paper and press at the other end.
Treat it as a good-faith preview, not a color contract. For brand-critical colors — a logo blue, a signature red — do one of two things:
- Define them as spot colors so they print from a named ink rather than a CMYK mix, and
- Check them against a printed swatch book (a Pantone or process guide) rather than trusting the screen.
Tip: no two monitors agree perfectly. If color accuracy is mission-critical, a printed proof from your actual print provider is the only true reference.
The out-of-gamut warning
The gamut is the range of colors a process can reproduce. Because CMYK's gamut is smaller than your screen's, some colors you can display simply can't be printed with process inks.
In a CMYK document, the color popover flags these. A color that falls outside the printable range is marked Outside the CMYK print gamut, with the note:
"This color is outside the CMYK gamut and will look duller in print."
The usual culprits are neon and electric values, and pure, highly saturated blues and greens — the colors that glow on a screen precisely because they rely on emitted light that ink can't mimic. When you see the badge, nudge the color toward something the press can hold, or accept that it will print more muted than it looks on canvas.
The high-ink-coverage warning
There's a second, quieter limit: how much ink can physically sit on one spot of paper. Add up the four channels of a color — C + M + Y + K — and you get its total area coverage (TAC). Pile on too much and Popcorn Editor warns:
"High ink coverage (N%). Most presses cap total ink near 300%."
Beyond that ceiling, ink struggles to dry, sheets stick together and offset onto each other (set-off), and plates can drift out of register. This is most often triggered by a "rich black" recipe that stacks heavy CMY under solid K. Keep the total near or below the press cap — this is the reason a well-built rich black uses moderate CMY, not maximum values.
Proofing on demand
The two warnings above are always on. For a closer look, View ▸ Proof colors simulates the press profile across the whole canvas, and View ▸ Gamut warning highlights every out-of-gamut area at once; a small pill on the canvas shows when a proof is active. The Proof preview panel in Properties goes further — a Composite or per-plate Separations view plus a total-ink (TAC) coverage overlay — so you can vet a print job before you export. The dedicated Soft-proof & separations guide walks through it.
When to use which
| You're making… | Use |
|---|---|
| Web graphics, social posts, on-screen slides | RGB (screen) |
| Anything physically printed — labels, cards, packaging, flyers | CMYK (print) |
The one rule worth remembering: for print, set CMYK (print) before you choose colors, so the soft-proof and the two warnings above steer you from the start rather than forcing a repaint later.
Where to go next
Now that your document speaks ink, keep brand colors exact with Spot colors & print separations, or take the file to output with Exporting a print-ready PDF. For a plain-English take on why colors shift, read RGB vs CMYK: why your colors change in print. And before you send, the preflight checks repeat these warnings one last time.