What's the difference between choosing "Assign" or "Convert" when changing color space from RGB to CMYK?

[BofG]

3 hours ago, v_kyr said:

See:

• PDF/X in a Nutshell (...of course as a PDF file LOL)

Interestingly (or confusingly).. in that document it states:

"All PDF/X formats require that an output intent is defined (see “Technical side and requirements of PDF/X”, page 7 that uses an ICC profile to characterize the intended output. Output intents use normally CMYK ICC profiles, but for PDF/X-4 or PDF/X-3 that can also be RGB or even Gray profiles."

So you can have an RGB output intent in a pdf/x-4, but if you try that in Affinity you get SWOP. The PDF spec does mention though that such a thing is for pdf/a, but I think there was a statement saying pdf/x specifications take precedence if there's a conflict in the documentation.

So now I'm back to square one, maybe I'll have to find the officially official pdf/x-4 spec and find out for sure, unless someone here knows the definitive answer and can save me the effort

[v_kyr]

2 minutes ago, BofG said:

So now I'm back to square one, maybe I'll have to find the officially official pdf/x-4 spec and find out for sure, unless someone here knows the definitive answer and can save me the effort

Some prepress printing domain people should know for sure here, as it's -among other prepress things- their daily bread to generate and use correct defined PDF/X4 stuff!

[LogosByDim]

Yes, someone who works with these printing files should know.

I'm just a little confused of why you would want a RGB profile as the Output Intent profile, instead of CMYK. If all the graphics in a PDF/X are in RGB, as you exported them in Affinity Designer, they stay in RGB. Only when printing the document all the profiles are overrided by the CMYK profile, not being converted as I thought earlier. So, even though every element in a PDF/X can be in RGB, the output intent profile in CMYK overrides them for the printing process.

Why would you want RGB as a profile in the Output Intent? Isn't the whole point of theese sort of PDFs to use for printing? I don't know how you would print in RGB. 

[BofG]

33 minutes ago, LogosByDim said:

Why would you want RGB as a profile in the Output Intent?

Some large format machines now have additional inks (orange being a common one) which takes it beyond any CMYK gamut. I guess the RIP is free to ignore the output intent and work from the RGB ICC colours directly from the document. That could mean though that what comes out doesn't match what a normal reader shows, because the reader will likely apply the output intent.

[LogosByDim]

6 hours ago, BofG said:

I guess the RIP is free to ignore the output intent and work from the RGB ICC colours directly from the document. That could mean though that what comes out doesn't match what a normal reader shows, because the reader will likely apply the output intent.

Thanks, I see what you mean now. So ideally you need the PDF/X document to both have the graphics in RGB and the Output Intent to be in RGB, instead of SWOP CMYK?

Perhaps you can create a new output intent in RGB and assign it do the document. I think it can be done in Adobe Acrobat Pro:

(Read more)

I've never done it, but maybe there is an option to create a new output intent as shown above, in a RGB profile. Then assign it to the previous CMYK output intent that you want to replace. 

Could that work for you?

[BofG]

Thanks, interesting to see. I'm mostly just musing - I don't need to produce such a file. I fell into the hole of colour management when I got a small digital press, and I couldn't get accurate colours to print from Designer (it turned out that Designer cannot send cmyk data). From there I've just taken an interest, and there's a wealth of knowledge in the members here so I like to get involved and try to learn more.

With acrobat, can you specify the colour model as well? So can you take a pdf and convert the actual colour data to a new profile, as well as setting the output intent?

[LogosByDim]

29 minutes ago, BofG said:

So can you take a pdf and convert the actual colour data to a new profile, as well as setting the output intent?

Your most welcome. I came here while doing my RGB to CMYK conversion of my logos, and wanted to learn the difference between assign and convert as the title of this topic says. It turned out it only matters when changing color profiles within the same color model.

Anyways, as per your question, I haven't been using Acrobat to change output intents before, or convert the color data. 

I think the color profiles should be assigned or converted in Designer, if any changes are needed, and then export a new PDF. Because I don't know if Acrobat can change color profiles. 

However, I do believe it is possible to change the output intent of the PDF since that cannot be done in Designer as far as I know. I can check that out if you want.

[BofG]

45 minutes ago, LogosByDim said:

I can check that out if you want.

I won't trouble you, was just if you knew off the top of your head. I'll take a look on the Adobe website, I want to get my head around all the acrobat functions anyway, I might have to subscribe to it for a bit to see what it's like.

Overall though I do think Affinity could use some improvements in this area. Would be nice to have a more featured pdf output where it's all less ambiguous. 

[LogosByDim]

You can download and install Adobe creative cloud application for desktop and from there you can try all the applications for 7 days as a trial version. Includes all the features in all the programs, so you can try Adobe Acrobat Pro without having to pay that expensive subscription in the first week.

I didn't find an option in Designer to edit the output intent of the PDF file. Perhaps Affinity Publisher has more advanced exporting features, I have no idea since I don't have Publisher.

However, I think Designer does it's job to export the graphics with the right color data and profiles, and from there the PDF reader takes over to finalize and optimize the rest of the configurations for print.

PDF readers like Acrobat Pro have the tools to edit the output intent, I read on that article in previous answer. That's what will affect how the file is previewed and printed as you said. But I think these settings are not for the exported content itself and more about the printing of the document. Hence, it isn't available to tweak in Designer. 

That's what I think about the matter at least. 

[RedSonia]

Since this is a more or less current thread, here are my 2 cents.  I'm a primarily print designer in the US, and CorelDraw is my primary design program (use CS4/CS6 as well).  It is driving me insane that there is no way to force Affinity Designer to default to CMYK -- and, yes, I'm setting up presets, but it's still annoying as hell. 

I ALWAYS design in CMYK, even where there will be a web or PMS color use of a logo, for instance (which there almost always is).  I'd much rather start with what is possible in print, and for almost every client I then create a file with the logo in every possible color use -- RGB/PMS/grey scale and CMYK.

And, I don't rely on the screen, or my CMYKRG inkjet printer, because they're irrelevant.  I have printed color books that I reference when I need them (been doing this a long time and have standard palettes, so don't need to do it that much).  The printed books aren't always perfect, and because ink on paper is a VERY imprecise "science" (more art), no matter what you do colors will shift a little bit.  But, by relying on printed samples, I get much closer to what I want as an end result, for CMYK and PMS.  The two most useful CMYK books for me are Process Color Manual and the 1995 PMS swatch book, just FYI.

I'm barely into trying to figure AD out, and may well have a fit about color palettes when I get that far.  Hoping that AD will let me set up a standard CMYK color palette that is in EVERY document.  Sigh. (Further annoyed about the grid not being able to be the default for all documents, and rounding my desired .0625 grid (1/16" of an inch) to .063, plus not being able to toggle snap to grid on and off....another item on my wish list.)

But glad you all are out there, so I can try to figure AD out!

[LogosByDim]

Hi RedSonia, welcome to our sparse thread, thank you for sharing your input and concern. 

Could you explain in more detail what you are facing regarding the default of CMYK? If you don't like to use a "pess ready" preset each time you open a document to set the color mode to CMYK, why not try setting up a document "template"? You can create new document using a preset, open the tool panels you like to use and the layers you always have in a new document, as well as the color settings. Then go to file, export as template. You can then use this CMYK template in ever document. Just open AD, clik templates, click add folder (the one which you exported the template), and select it to be used as a new document. Could that help you default to CMYK?

You have a good process of color usage, it sounds reliable with color guides.

You can actually set up a standard CMYK color palette, I believe. You can go to the "swatches panel", in the options there, add a new palette, add in the fills or CMYK colors you use the most, and save export this document as a template. Every time you open AD and create a new document using this template you'll have these colors in that new color palette. I think this can be done that way.

This was all on top of my head, If you need more in-depth guidance on any of these points feel free to ask in more detail about your concerns. Have a nice day!

[feelingprettyred]

On 11/21/2020 at 1:38 PM, Lorox said:

I guess Chris26 (and the article he'd referred to) made the topic relatively clear and understandable – at least as we're talking about RGB colour mode. This given, I'd think this will be useful predominantly for photographers whereas converting from RGB to CMYK (and possibly from one CMYK profile to another) will be important to designers doing work that is bound to be commercially printed using e.g. offset printing.

In this area it might be crucial that certain colours will not be changed at all and be printed with the exact CMYK values which had initially been assigned to them (e.g. for some corporate design or house style) whereas colours in pictures (RBG and/or CMYK) placed in the design actually should be converted to fit the actual printing process/workflow and thus appear – visually – unchanged in the end (while in fact their colour numbers/values have been more or less altered in the process).

It can actually get a bit complicated when a proper prepress workflow is concerned. In this respect Affinity Publisher has given me some headaches recently as black text/type – which in CMYK printing should normally be just 100% black (with no C, M or Y in it) – had turned out to be a mix of all the four components of CMYK in the PDF meant for sending to the printer's shop. It could be corrected in the end, but one has to double check and be quite careful – mistakes can happen easily as it seems.

Hey, sorry im late but reading through this im having the exact same problem with 100 black, as you can see on my profile, how did you fix it? i have so many print jobs and im having to work back in AI as i just can not get 100|K black in affinity

[LogosByDim]

Hi there @feelingprettyred

Take a look at the Color Panel in Publisher, switch the color wheel to CMYK values and set all values to zero except black (K) to 100%. Export your PDF file from Publisher.

Now use Adobe Acrobat to check if the text is exported in pure black CMYK value without any Cyan, Magenta or Yellow. Here's how to do that:

“Using Acrobat DC: At the top of your screen you should see a Tools tab, click it and then find Print Production, then Output Preview. In the Output Preview panel, select Show: All and Preview: Separations.”

Source: (Adobe Community)

Now you should be able to click the text in the PDF and get an overview of the CMYK color values used for the text. Ensure only 100% Key (black) is used.

I hope this helps! Let me know once you try it!

— Dimitar

[feelingprettyred]

27 minutes ago, LogosByDim said:

Hi there @feelingprettyred

Take a look at the Color Panel in Publisher, switch the color wheel to CMYK values and set all values to zero except black (K) to 100%. Export your PDF file from Publisher.

Now use Adobe Acrobat to check if the text is exported in pure black CMYK value without any Cyan, Magenta or Yellow. Here's how to do that:

“Using Acrobat DC: At the top of your screen you should see a Tools tab, click it and then find Print Production, then Output Preview. In the Output Preview panel, select Show: All and Preview: Separations.”

Source: (Adobe Community)

Now you should be able to click the text in the PDF and get an overview of the CMYK color values used for the text. Ensure only 100% Key (black) is used.

I hope this helps! Let me know once you try it!

— Dimitar

Hey thankyou but i understand the basic principles, my problem being when all my profiles are CMYK, all blacks are set to 0 0 0 100, my black still doesn't come out 100K in acrobat. i have not idea why, it isn't something infant of me, t this point im geneuily putting it down too the software. i can take the same broken file that won't show 100k, export to EPS, bring into AI to PDF, and when the same file with not adjustments just taken through AI instead of AD produces 100k black as the values are set. 

[Lorox]

43 minutes ago, feelingprettyred said:

Hey, sorry im late but reading through this im having the exact same problem with 100 black, as you can see on my profile, how did you fix it? i have so many print jobs and im having to work back in AI as i just can not get 100|K black in affinity

Hi, as it's been a while I'm unfortunately not quite sure anymore what I exactly did... However, one the one hand I remember I did some test runs using different settings for exporting my PDFs. On the other hand I tried to make sure I was using the desired CMYK colour profile right from the start in any of my documents. Last but not least I deleted that ”Greys“ pallette which came with Publisher as those greys (including the Black within that pallette) weren't just ”K greys“  but actually ”rich“ greys made of percentages of all the CMYK colours – especially the „Black“ therein caused problems as it also was a ”rich“ CMYK-Black. After deleting the old one set up a new ”Greys“ application pallette which is made of a 100% K Black and corresponding shades of that ”proper“ Black.

So far this has worked for me, but I tend to be cautious and always check my PDFs for printing services on another computer that still got Acrobat Pro running...

[LogosByDim]

Hi, maybe setting up a global color swatch with CMYK values 0 0 0 100 and making it a "spot color" with "overprint" could ensure the exported PDF has only 100% black?

Assign this spot global color with overprint to the text and export the PDF. I read this in another thread but can't remember the output results.