Vectors, Logos and Things That Get PrintedLesson 29 of 73

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Vectors, Logos and Things That Get Printed

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Module 4 · Colour that survives the press

Profiles, and the dialog that decides everything

9 min read

Two menu items, opposite jobsThe numbersThe appearanceAssignUntouchedthe file is not editedChangesnow read differentlyConvertRewrittennew values writtenPreservedsame measured colourAssign when you know what the file is and its tag is wrong or missing. Convert when you are moving thefile to a different device. Assigning sRGB to an Adobe RGB photograph flattens it; converting the samefile twice loses whatever fell outside the gamut the first time.
Assign when you know what the file is and its tag is wrong or missing. Convert when you are moving the file to a different device. Assigning sRGB to an Adobe RGB photograph flattens it; converting the same file twice loses whatever fell outside the gamut the first time.

Figure

What a profile is

An ICC profile is a lookup table plus some maths that translates between a device’s own numbers and a device-independent space: Lab or CIEXYZ, called the Profile Connection Space.

An RGB profile says: on this device, R 200 G 30 B 40 produces this Lab value. A CMYK profile says: on this press, on this paper, C 0 M 90 Y 85 K 0 produces this Lab value.

Every colour conversion is therefore two steps: source device numbers → PCS → destination device numbers. Both profiles must be right for the answer to be right.

Assign versus convert, which is the whole lesson

Two menu items, adjacent in most applications, doing opposite things.

Assign profile changes the interpretation and leaves the numbers alone. The file still says R 200 G 30 B 40; you have changed what that means. The colour on screen changes. The pixels do not.

Convert to profile changes the numbers to preserve the appearance. The file becomes R 193 G 52 B 47, or whatever the destination needs to produce the same Lab value.

Get this the wrong way round and you either destroy colours or misdescribe them:

  • Assigning sRGB to a file that is actually Adobe RGB makes everything look flat and desaturated, because the saturated numbers are now being read as if they came from a narrower device.
  • Converting a file twice (to CMYK and back to RGB and to CMYK again) loses a little each time, because each conversion clips whatever fell outside the destination gamut and cannot recover it.

The rule: assign when you know what the file is and the tag is wrong or missing. Convert when you want to move the file to a different device.

Which profiles to use

For source RGB:

  • sRGB IEC61966-2.1: phones, web, almost everything. If a file has no tag, sRGB is the correct guess.
  • Adobe RGB (1998): wider in greens and cyans. Worth using only if your camera, screen and workflow all support it end to end.
  • Display P3: Apple devices and modern phones. Increasingly what a client’s photograph actually is.

For destination CMYK, and this matters more than most people realise, because a “CMYK” file converted with the wrong press profile is wrong:

  • FOGRA39 / ISO Coated v2: European coated sheetfed, total ink around 330%. The most widely used default.
  • FOGRA51 / PSO Coated v3: the updated version for modern papers with optical brighteners.
  • FOGRA47 / PSO Uncoated and FOGRA52: uncoated stock, lower ink limits, much larger dot gain.
  • GRACoL 2013 / CRPC6: the North American equivalent.
  • Japan Color 2001 Coated: widely used in Asia, and what many Indian shops’ RIPs are set to by default.

Ask your printer which one they are set to. It takes one line in an email and it is the difference between a proof that matches and one that does not. If they cannot tell you, ISO Coated v2 is a defensible default for coated work.

Free downloads: the European Color Initiative publishes the ECI profiles at no cost, and Adobe ships several in its applications. Ghostscript and Krita ship a set too.

Setting them up

  • Scribus: File ▸ Preferences ▸ Colour Management. Set the RGB working space, the printer profile, tick Simulate printer on screen for soft proofing. Scribus’s colour handling is the strongest of the free tools and the reason it is the free press chain’s export stage.
  • GIMP: Edit ▸ Preferences ▸ Colour Management, and Image ▸ Colour Management ▸ Assign / Convert as separate menu items, correctly named.
  • Krita: profiles set per document at creation; the soft-proof toggle is Ctrl+Y.
  • Inkscape: works internally in RGB; colour management is in Document Properties ▸ Colour and is thinner than the others. For press colour, hand off to Scribus.
  • Illustrator / InDesign: Edit ▸ Colour Settings, and Edit ▸ Assign Profile / Convert to Profile as separate items.

The commonest real failure

A photograph arrives from a client with no embedded profile. The application assumes sRGB. The photograph was actually shot in Adobe RGB. Nobody notices until the printed skin tones are slightly grey.

The fix is to ask, and the check is to look: an untagged file whose saturated colours look oddly flat is usually a wide-gamut file being read as sRGB. Assign Adobe RGB and see whether it comes alive. If it does, that was it.

Every lesson here is open. Your progress is recorded once you pass the Editing an Image exam.

Check your understanding

A client’s photograph arrives with no embedded ICC profile. Opened in the designer’s application it looks flat and desaturated, particularly in the greens. The photographer confirms it was shot and exported in Adobe RGB. What is the correct action?

Pick the one you would defend. Your answer stays private.

Next lesson · 8 minWhat happens to a colour the press cannot print

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How to cite: Addaly (2026) ‘Profiles, and the dialog that decides everything’, in Vectors, Logos and Things That Get Printed. Edited by M. Mun. Addaly. Available at: https://addaly.com/learn/vector-and-print/icc-profiles-assign-or-convert (Accessed: 13 October 2026).