Key facts
- RGB (red, green, blue) is additive light, used for screens; sRGB is the safe default for web
- CMYK (cyan, magenta, yellow, black) is subtractive ink, used for most print
- Bright greens, blues and oranges in RGB often fall outside the CMYK gamut
- Pantone spot colours give exact, consistent colour for logos and packaging
- Print images should be about 300 dpi at final size
- PDF/X-1a and PDF/X-4 are the common print-ready PDF standards
The difference in one table
| RGB | CMYK | |
|---|---|---|
| How colour is made | Adding red, green and blue light | Layering cyan, magenta, yellow and black ink |
| Used for | Websites, social media, apps, video, screens | Litho and most digital print: leaflets, brochures, packaging |
| Colour range | Wider, especially bright greens, blues and oranges | Narrower; varies with paper and press |
| Black | 0, 0, 0 | K 100, or rich black mixes for large areas |
| Typical files | PNG, JPEG, SVG, MP4 in sRGB | PDF/X-1a or PDF/X-4, TIFF |
| Values written as | RGB 0 to 255 or HEX (#1A73E8) | Percentages (C 100 M 45 Y 0 K 0) |
Why colours change when printed
A screen produces colour by emitting light, so it can show vivid, glowing tones. Print reflects light off paper through layers of ink, which limits the range of colours, called the gamut. When an RGB file is converted to CMYK, any colour outside the CMYK gamut is pulled to the nearest printable colour. Electric blues, neon greens and bright oranges suffer most.
Paper matters too. The same CMYK values print brighter on coated gloss than on uncoated stock, where ink soaks in and spreads. Printers use ICC profiles to predict this: in the UK and Europe, FOGRA39 has long been a common coated-paper profile, with newer FOGRA51 and FOGRA52 profiles for coated and uncoated stocks. Ask your printer which profile they want, and we will convert to it. For brand colours that must match closely across paper types, ask for a printed proof on the actual stock before the full run, because a screen preview cannot show how ink sits on a particular paper.
Pantone, rich black and other print details
Pantone spot colours are pre-mixed inks that print the same colour every time, which is why many brands specify a Pantone for their logo. They suit litho print, packaging and merchandise. On a CMYK-only job, the Pantone is converted to the nearest CMYK mix, so it will not match exactly.
Black needs care. Small black text should be 100% K only, so it stays sharp if the plates are slightly out of register. Large black areas often use a rich black, such as C 60 M 40 Y 40 K 100, to look deep rather than grey. Keep the total ink coverage within your printer's limit, often around 300% on coated paper.
Resolution: images should be roughly 300 dpi at the size they are printed. A 1080 px wide social image is only about 9 cm wide at 300 dpi. See vector vs raster for why logos should be vector instead.
Which file should you send?
For print, most UK printers ask for a PDF with 3 mm bleed and crop marks. PDF/X-1a flattens transparency and allows only CMYK and spot colours, which makes it predictable on older workflows. PDF/X-4 keeps live transparency and colour profiles, which suits modern presses. If unsure, ask your printer; we can supply either.
For screens, export RGB in the sRGB colour space: PNG for graphics with sharp edges or transparency, JPEG for photographs, SVG for logos and icons on websites. Converting a CMYK file back to RGB for web will not bring lost colours back, so keep master files in RGB or in a wide-gamut format and convert copies for print.
How we handle colour
When dijitul designs a brand, we define every colour in Pantone, CMYK, RGB and HEX so printers, web developers and sign makers all start from the right values. For print jobs we set up artwork in the profile your printer uses, flag any colours that will shift, and supply print-ready PDFs. Flyers start from £95 + VAT and brochures from £295 + VAT; fixing or preparing existing files is charged at £45 an hour + VAT. If you would like us to manage the printing too, see print management.
Frequently asked questions
Should I use CMYK or RGB for printing?
Use CMYK for most printed items, or Pantone spot colours where exact colour matters. RGB is for screens. Many printers will convert RGB files automatically, but colours may shift unpredictably. dijitul prepares print artwork in CMYK using the ICC profile your printer specifies.
Why does my logo look dull when printed?
Bright RGB colours, especially vivid blues, greens and oranges, can fall outside the range CMYK inks can print, so they are pulled to the nearest printable colour. Uncoated paper dulls colours further. A Pantone spot colour or a carefully chosen CMYK mix gets closer. dijitul can advise and adjust.
What resolution should images be for print?
Around 300 dpi at the final printed size. A 1080 pixel wide social media image is only about 9 cm wide at that resolution, so web images often look soft in print. Logos and text should be vector, which has no resolution limit.
What is the difference between PDF/X-1a and PDF/X-4?
Both are print-ready PDF standards. PDF/X-1a flattens transparency and allows only CMYK and spot colours, which is predictable on older workflows. PDF/X-4 keeps live transparency and ICC colour profiles, which suits modern print workflows. dijitul supplies whichever your printer requests.
What colour mode should I use for social media?
RGB, in the sRGB colour space, exported as PNG for graphics and JPEG for photos. CMYK files can display oddly on screens and some platforms reject them. dijitul supplies social media graphics in sRGB at current platform sizes, with packs from £99 + VAT.
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