{"course":{"slug":"vector-and-print","title":"Vectors, Logos and Things That Get Printed","url":"https://addaly.com/learn/vector-and-print","level":"beginner","track":"create"},"lesson":{"slug":"icc-profiles-assign-or-convert","title":"Profiles, and the dialog that decides everything","url":"https://addaly.com/learn/vector-and-print/icc-profiles-assign-or-convert","position":29,"of":73,"minutes":9,"answer":"Assign changes what the existing numbers mean; convert changes the numbers to preserve the appearance, and a CMYK conversion is only as correct as the press profile you converted to.","keyIdea":"Assign changes what the existing numbers mean; convert changes the numbers to preserve the appearance, and a CMYK conversion is only as correct as the press profile you converted to, which is a question for your printer rather than a default."},"body":{"format":"markdown","text":"## What a profile is\n\nAn **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**.\n\nAn 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.*\n\nEvery colour conversion is therefore two steps: source device numbers → PCS → destination device numbers. Both profiles must be right for the answer to be right.\n\n## Assign versus convert, which is the whole lesson\n\nTwo menu items, adjacent in most applications, doing opposite things.\n\n**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.\n\n**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.\n\nGet this the wrong way round and you either destroy colours or misdescribe them:\n\n> Figure: Two menu items, opposite jobs. A two by two grid, rows Assign and Convert, columns The numbers and The appearance: Assign and The numbers: Untouched; Assign and The appearance: Changes; Convert and The numbers: Rewritten; Convert and The appearance: Preserved. 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.\n\n- **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.\n- **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.\n\nThe 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.**\n\n## Which profiles to use\n\nFor source RGB:\n\n- **sRGB IEC61966-2.1**: phones, web, almost everything. If a file has no tag, sRGB is the correct guess.\n- **Adobe RGB (1998)**: wider in greens and cyans. Worth using only if your camera, screen and workflow all support it end to end.\n- **Display P3**: Apple devices and modern phones. Increasingly what a client's photograph actually is.\n\nFor destination CMYK, and this matters more than most people realise, because a \"CMYK\" file converted with the wrong press profile is wrong:\n\n- **FOGRA39 / ISO Coated v2**: European coated sheetfed, total ink around 330%. The most widely used default.\n- **FOGRA51 / PSO Coated v3**: the updated version for modern papers with optical brighteners.\n- **FOGRA47 / PSO Uncoated** and **FOGRA52**: uncoated stock, lower ink limits, much larger dot gain.\n- **GRACoL 2013 / CRPC6**: the North American equivalent.\n- **Japan Color 2001 Coated**: widely used in Asia, and what many Indian shops' RIPs are set to by default.\n\n**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.\n\nFree 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.\n\n## Setting them up\n\n- **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.\n- **GIMP**: Edit ▸ Preferences ▸ Colour Management, and Image ▸ Colour Management ▸ Assign / Convert as separate menu items, correctly named.\n- **Krita**: profiles set per document at creation; the soft-proof toggle is **Ctrl+Y**.\n- **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.\n- **Illustrator / InDesign**: Edit ▸ Colour Settings, and Edit ▸ Assign Profile / Convert to Profile as separate items.\n\n## The commonest real failure\n\nA 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.\n\nThe 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."},"check":{"question":"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?","options":[{"text":"Convert the file to Adobe RGB, which will restore the saturation the numbers originally carried.","correct":false,"tempting":"Converting from an assumed sRGB to Adobe RGB changes the numbers to preserve the flat appearance you are looking at, locking in the error."},{"text":"Assign Adobe RGB, leaving the numbers alone so they are read against the correct device description.","correct":true},{"text":"Increase saturation in an adjustment layer until the greens look correct, then convert to the press CMYK profile.","correct":false,"tempting":"Treats a misinterpretation as an aesthetic problem. Manual correction guesses at a transform that a single assignment performs exactly."},{"text":"Re-export the file from the original camera raw with sRGB selected, since the application cannot read Adobe RGB reliably.","correct":false,"tempting":"Applications read Adobe RGB perfectly well; the file simply failed to say what it was. Going back to raw is unnecessary work for a tagging problem."}]},"prev":{"slug":"device-independent-colour","title":"Lab, Delta E, and what \"close enough\" means","url":"https://addaly.com/learn/vector-and-print/device-independent-colour"},"next":{"slug":"gamut-and-rendering-intents","title":"What happens to a colour the press cannot print","url":"https://addaly.com/learn/vector-and-print/gamut-and-rendering-intents"},"authorship":"Founder and series editor: Dr Mustafa Mun. Written by AI models to a written standard. Exam keys checked blind by a second model: 3,665 of 3,666 agreed. Academic review invited.","review":{"status":"Draft, open for academic review"},"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).","licence":{"name":"CC BY-NC-SA 4.0","url":"https://creativecommons.org/licenses/by-nc-sa/4.0/"},"reader":{"schema":1,"title":"Profiles, and the dialog that decides everything","courseTitle":"Vectors, Logos and Things That Get Printed","module":{"index":4,"slug":"colour-for-print","title":"Colour that survives the press"},"answer":null,"keyIdea":"Assign changes what the existing numbers mean; convert changes the numbers to preserve the appearance, and a CMYK conversion is only as correct as the press profile you converted to, which is a question for your printer rather than a default.","hero":{"kind":"figure","figure":{"t":"figure","label":"Figure","figure":{"cols":["The numbers","The appearance"],"rows":["Assign","Convert"],"type":"matrix","cells":[["Untouched","Changes"],["Rewritten","Preserved"]],"title":"Two menu items, opposite jobs","caption":"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.","cellLabels":[["the file is not edited","now read differently"],["new values written","same measured colour"]]},"alt":"Figure: Two menu items, opposite jobs. A two by two grid, rows Assign and Convert, columns The numbers and The appearance: Assign and The numbers: Untouched; Assign and The appearance: Changes; Convert and The numbers: Rewritten; Convert and The appearance: Preserved. 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."}},"blocks":[{"t":"h2","id":"what-a-profile-is","runs":[{"text":"What a profile is"}]},{"t":"p","runs":[{"text":"An "},{"text":"ICC profile","b":true},{"text":" 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 "},{"text":"Profile Connection Space","b":true},{"text":"."}]},{"t":"p","runs":[{"text":"An RGB profile says: "},{"text":"on this device, R 200 G 30 B 40 produces this Lab value.","i":true},{"text":" A CMYK profile says: "},{"text":"on this press, on this paper, C 0 M 90 Y 85 K 0 produces this Lab value.","i":true}]},{"t":"p","runs":[{"text":"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."}]},{"t":"h2","id":"assign-versus-convert-which-is-the-whole-lesson","runs":[{"text":"Assign versus convert, which is the whole lesson"}]},{"t":"p","runs":[{"text":"Two menu items, adjacent in most applications, doing opposite things."}]},{"t":"p","runs":[{"text":"Assign profile","b":true},{"text":" changes the "},{"text":"interpretation","i":true},{"text":" 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."}]},{"t":"p","runs":[{"text":"Convert to profile","b":true},{"text":" changes the "},{"text":"numbers","i":true},{"text":" to preserve the appearance. The file becomes R 193 G 52 B 47, or whatever the destination needs to produce the same Lab value."}]},{"t":"p","runs":[{"text":"Get this the wrong way round and you either destroy colours or misdescribe them:"}]},{"t":"ul","items":[[{"text":"Assigning","b":true},{"text":" 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."}],[{"text":"Converting","b":true},{"text":" 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."}]]},{"t":"p","runs":[{"text":"The rule: "},{"text":"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.","b":true}]},{"t":"h2","id":"which-profiles-to-use","runs":[{"text":"Which profiles to use"}]},{"t":"p","runs":[{"text":"For source RGB:"}]},{"t":"ul","items":[[{"text":"sRGB IEC61966-2.1","b":true},{"text":": phones, web, almost everything. If a file has no tag, sRGB is the correct guess."}],[{"text":"Adobe RGB (1998)","b":true},{"text":": wider in greens and cyans. Worth using only if your camera, screen and workflow all support it end to end."}],[{"text":"Display P3","b":true},{"text":": Apple devices and modern phones. Increasingly what a client’s photograph actually is."}]]},{"t":"p","runs":[{"text":"For destination CMYK, and this matters more than most people realise, because a “CMYK” file converted with the wrong press profile is wrong:"}]},{"t":"ul","items":[[{"text":"FOGRA39 / ISO Coated v2","b":true},{"text":": European coated sheetfed, total ink around 330%. The most widely used default."}],[{"text":"FOGRA51 / PSO Coated v3","b":true},{"text":": the updated version for modern papers with optical brighteners."}],[{"text":"FOGRA47 / PSO Uncoated","b":true},{"text":" and "},{"text":"FOGRA52","b":true},{"text":": uncoated stock, lower ink limits, much larger dot gain."}],[{"text":"GRACoL 2013 / CRPC6","b":true},{"text":": the North American equivalent."}],[{"text":"Japan Color 2001 Coated","b":true},{"text":": widely used in Asia, and what many Indian shops’ RIPs are set to by default."}]]},{"t":"p","runs":[{"text":"Ask your printer which one they are set to.","b":true},{"text":" 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."}]},{"t":"p","runs":[{"text":"Free downloads: the "},{"text":"European Color Initiative","b":true},{"text":" publishes the ECI profiles at no cost, and "},{"text":"Adobe","b":true},{"text":" ships several in its applications. Ghostscript and Krita ship a set too."}]},{"t":"h2","id":"setting-them-up","runs":[{"text":"Setting them up"}]},{"t":"ul","items":[[{"text":"Scribus","b":true},{"text":": File ▸ Preferences ▸ Colour Management. Set the RGB working space, the printer profile, tick "},{"text":"Simulate printer on screen","i":true},{"text":" 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."}],[{"text":"GIMP","b":true},{"text":": Edit ▸ Preferences ▸ Colour Management, and Image ▸ Colour Management ▸ Assign / Convert as separate menu items, correctly named."}],[{"text":"Krita","b":true},{"text":": profiles set per document at creation; the soft-proof toggle is "},{"text":"Ctrl+Y","b":true},{"text":"."}],[{"text":"Inkscape","b":true},{"text":": works internally in RGB; colour management is in Document Properties ▸ Colour and is thinner than the others. For press colour, hand off to Scribus."}],[{"text":"Illustrator / InDesign","b":true},{"text":": Edit ▸ Colour Settings, and Edit ▸ Assign Profile / Convert to Profile as separate items."}]]},{"t":"h2","id":"the-commonest-real-failure","runs":[{"text":"The commonest real failure"}]},{"t":"p","runs":[{"text":"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."}]},{"t":"p","runs":[{"text":"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."}]}],"check":{"question":[{"text":"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?"}],"options":[{"text":[{"text":"Convert the file to Adobe RGB, which will restore the saturation the numbers originally carried."}],"correct":false,"tempting":[{"text":"Converting from an assumed sRGB to Adobe RGB changes the numbers to preserve the flat appearance you are looking at, locking in the error."}]},{"text":[{"text":"Assign Adobe RGB, leaving the numbers alone so they are read against the correct device description."}],"correct":true,"tempting":null},{"text":[{"text":"Increase saturation in an adjustment layer until the greens look correct, then convert to the press CMYK profile."}],"correct":false,"tempting":[{"text":"Treats a misinterpretation as an aesthetic problem. Manual correction guesses at a transform that a single assignment performs exactly."}]},{"text":[{"text":"Re-export the file from the original camera raw with sRGB selected, since the application cannot read Adobe RGB reliably."}],"correct":false,"tempting":[{"text":"Applications read Adobe RGB perfectly well; the file simply failed to say what it was. Going back to raw is unnecessary work for a tagging problem."}]}],"order":[2,3,0,1],"why":null},"prev":{"slug":"device-independent-colour","title":"Lab, Delta E, and what “close enough” means","minutes":8},"next":{"slug":"gamut-and-rendering-intents","title":"What happens to a colour the press cannot print","minutes":8}}}