Inspiring

Question

RIP introducing CMY into grey when grey only contains K

Forum|Forum|2 months ago
November 19, 2025
2 replies
166 views

We have created literally thousands of pieces of artwork in Indesign that have been exported as PDF and sent to various large format printers over many years. Recently it came to light that one of the PDFs containing tints of black had printed 'brown' by introducing cyan, magneta and yellow into the mix. The InDesign file showed as pure black, the exported PDF only showed pure black, but CM and Y were printed in addition to the black.

On the face of it, because the PDF shows no cyan, magenta or yellow in the grey, the blame would be placed on the RIP, but is this the case? Is it possible to create a PDF that shows one CMYK mix but prints another?

Indesign is set to CMYK, synched to Europe General Purpose 3,
PDF 1.6, PDF/X-4:2010, no colour conversion. Intent profile: document CMYK coated FOGRA39

rob day

Community Expert

sent to various large format printers

Hi @nawest , With very few exceptions large format composite inkjet printers handle final color conversions internally—the profile for an inkjet printer is very different than an offset press profile.

You are preparing your files as if they are going to an offset press running to the CMYK FOGRA39 press profile, and exporting to the PDF/X-4 press preset, which does not include profiles for document CMYK colors. PDF/X standards include an Output Intent profile, which your RIP would not likely see. So your inkjet printer doesn’t know how to color manage the CMYK colors with no source profile.

You could try including all profiles—something like this:

N

nawestAuthor

Inspiring

Thanks Rob

I suppose you could call it ignorance, but even after many years in the industry providing artwork to many clients and printers, the area of colour management is still somewhat of a grey area for me. That said, the number of times that issues have been raised in those years would imply that 99.9% of the time it hasn't been an issue.

That said, you're right, I'm supplying artwork spec'd for offset printing and not large format digital, but in my experience very few printers, litho, flexo or otherwise, supply specifications for this level of detail. They'll invariably just ask for hi-res PDFs with fonts embedded, and no mentions of standards or profiles. It's only on occasions like this whe jobs go wrong that the question gets asked.

I'll certainly send them a new test using your suggested settings though.

rob day

Community Expert

that 99.9% of the time it hasn't been an issue.

Is your output typically to composite inkjet printers or offset presses? The color mangement for inkjet is really different.

E

Eugene Tyson

Community Expert

If the printer’s RIP is using a different colour profile than the one embedded in your PDF, it can convert your pure K tints into a 4-colour black during processing. That’s one of the most common reasons a clean K-only grey suddenly turns into a CMYK mix on press.

Another possibility is that someone at their end opened the PDF in Illustrator or another application not intended for editing PDFs. Illustrator in particular can reinterpret colour spaces or introduce unwanted colour conversions when a PDF is forced into its native editing model.

But the key point is this:
Your InDesign file shows pure K, and your exported PDF shows pure K in the separations. That means the CMY was introduced after the file left you.

Any competent printer should have checked separations at the RIP stage. Seeing four plates for elements that are supposed to be black-only should have been an immediate red flag. The fact that this wasn’t caught suggests:

They ran it digitally and their RIP forced a rich black / composite build, or
It was gang printed with no individual colour management, meaning “whatever comes out, comes out,” and they didn’t take the time to ensure the greys were running as K-only.

If the supplied PDF contains only K, and the output shows CMY, then the issue lies entirely with their workflow or RIP settings not your artwork. You’re not responsible for how their output device handles colour conversions.

Then again I haven't seen your file - and I haven't seen the output - or the file they output - so going on the evidence so far - the onus is on them.

N

nawestAuthor

Inspiring

Thanks Eugene, I'm of the same opinion that the issue lies with the RIP. Research suggests there's a few reasons why the RIP would make such changes especially on large areas of grey, but I'm not in control of the RIP and have little influence. The printer did look into the issue and, as a test, asked me to convert the Indesign file into Illustrator (their weapon of choice) and resupply. They then exported a PDF from the ai file at their end and the resulting print came out fine (which it would). They have asked that all future PDFs be exported from Illustrator! For so many reasons, this clearly isn't the solution.

It's been a fair few years since I worked in repro, but I recall we had the ability to visually check the RIP'd files onscreen before printing films (yes, that long ago!). This particular printer doesn't appear to have that facility, so the RIP'd files go straight to print without checking, and it's only at that stage that any issues become apparent. This appears to be a glaring omission to me, and the inclusion of such a facility would make at least the testing so much easier.

I've passed my research onto them and am awaiting a reply.

E

Eugene Tyson

Community Expert

There you go - my inkling was right - at least I think it is - I think they are opening it in illustrator which is wrong.

Any printing house asking to you to submit everything as Illustrator or Illustrator PDFs are not worth their salt.

I'd be inclined to ditch them to be honest.

This is my personal opinion.

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