Inconsistent color shift on PDF export

[Walter Nissen]

I have an JPEG from a client in RGB mode. If I import the JPEG into Mac PowerPoint, the Mac color picker says the blue background is RGB 108 215 255 (aka hex #6CD7FF) or CMYK 42% 4% 1% 0%. When I place the JPEG in a CMYK/8 Affinity Publisher document with the “Coated FOGRA39 (ISO 12647-2:2004” profile and use the Affinity color picker it says the RGB is 127 206 243 (aka hex 7FCEF3) and CMYK is 51 0 1 0. Visually the color match is very close on my screen, which is an Apple Studio display and comes factory calibrated. But when I export to PDF (whether for print or digital), the colors get very different. The logo gets much brighter relative to the background, which I picked to be the same color. I expect some color shift of all the colors on export, but why does it look the same on my screen but not in the PDF? MY .afpub and .pdf are attached. Thanks!

 

1 Page.pdf 1 Page.afpub

Edited March 22, 2023 by Walter Nissen
Added screenshot and original JPEG demonstrating issue.

[Hangman]

Hi @Walter Nissen and welcome to the forums...

Could you upload the JPEG file as well... the issue will be to do with colour conversion between two different colour spaces but having the JPEG file will allow us to suggest a solution for you. You will just need a slightly different approach to achieve what you need.

 

[Walter Nissen]

27 minutes ago, Hangman said:

Hi @Walter Nissen and welcome to the forums...

Could you upload the JPEG file as well... the issue will be to do with colour conversion between two different colour spaces but having the JPEG file will allow us to suggest a solution for you. You will just need a slightly different approach to achieve what you need.

 

Thanks for the welcome! I attached the original RGB file with the solid background. 

[Hangman]

Just now, Walter Nissen said:

Thanks for the welcome! I attached the original RGB file with the solid background.

The JPEG file is Linked in your Publisher document so we don't have the physical JPEG file itself prior to being colour converted which was the reason for requesting it...

[tudor]

@Walter Nissen In the PDF export window, enable the "Convert image color spaces" option. Here is a PDF sample:

1 Page 02.pdf

[Walter Nissen]

21 minutes ago, tudor said:

@Walter Nissen In the PDF export window, enable the "Convert image color spaces" option. Here is a PDF sample:

1 Page 02.pdf 815.26 kB · 1 download

Thank you! That worked, I got consistent color! Is there a way to convert all the image color spaces when they are placed, that would be what I'd want, I think?

Interestingly, the PDF preview inside AFPUB still shows the unconverted color space, for some reason (see below). If there's a way to fix that too, I would be interested.

Thanks again for your help!

[tudor]

Here the preview looks fine.

[Walter Nissen]

35 minutes ago, tudor said:

Here the preview looks fine.

Weird, I even tried turning of True Tone, I am not sure what is going on. The PDF being right is the important thing. I’m running macOS Ventura 13.2.1 (22D68) on a 2021 M1 MacBook Pro, for what it’s worth. 

[lacerto]

Obsolete.

[Walter Nissen]

6 hours ago, lacerto said:

There is color management going on 🙂 The export preview is not color managed so it shows the RGB based image without applying it the document CMYK target profile, while when you have your Publisher document in CMYK mode, this will be done (as if you had a permanent Soft proof turned on).

Here is a demonstration on what happens if you switch the document color mode from CMYK to RGB: the RGB image will be shown in its RGB color gamut so the same difference between the blue colors that was shown in export preview is now shown also on the canvas. The blue rectangle, that was initially defined in CMYK does not change (as the sRGB color space covers this specific tone of blue). Because CMYK is generally a narrower color gamut than (s)RGB, the more saturated light blue will become duller when converted to CMYK, or when its visual appearance simulated in a specific CMYK color space.

 

[Btw. Note the bug in version 2 apps when switching the color mode from RGB back to CMYK. The app seems to offer the current working CMYK color profile as defined in Pferences > Color, but actually the profile is not selected (this could be seen when re-visiting the File > Document Setup > Color immediately after closing the dialog box: the previously active CMYK color profile would shown being the active CMYK color profile.]

Note how an Image layer will not be converted when switching the color mode of the document -- nor will text or shape layers; the color mode and original definitions of the latter two (i.e., the native objects) stays untouched, as long as the lock of the Color panel is turned on. You can have these objects selected and switch between different color models within the Color panel and check how the colors would be converted in the current profile environment. However, when the lock is turned off, having an object selected and simply just switching the color model from richer to narrower gamut (like from sRGB to CMYK), will make an actual conversion and will redefine the color of the objects. Similarly, a copy of a placed bitmap, which is rasterized on screen, will become a Pixel layer, and be converted to the current document color mode (and would also automatically be converted when changing the document color mode, so this should basically not be done whenever having Pixel layers, since multiple conversions typically result in constant retranslation of colors, on successive times because of rounding errors). A converted image would then show consistently also in the export Preview.

Here is another clip that shows how a color managed viewer (in this case Adobe Acrobat Pro) can handle mixed color mode PDFs. A PDF can have multiple color spaces, but as long as profiles are embedded, an advanced viewer can simulate visual appearance of the final product. So it is not necessary to apply "Convert image color spaces" PDF setting to force conversion of RGB images to CMYK, as long as the PDF is correctly produced. Apps like Adobe Reader, macOS Preview app, etc. cannot apply simulation profiles, and depending on the way the PDF is produced, the user might be required to choose the correct profile themselves. 

 

While it is not necessary to have unified color space, this would typically be wanted when there is need to keep colors consistent disregarding whether producing for digital media or paper, and especially when the "same colors" in different color spaces overlap, like here. It could be achieved either by redefining the rectangle in (s)RGB color space, or like on the video, converting the bitmap to target CMYK color space. Often the more saturated RGB colors are wanted to be retained (especially in photos), so if the colors overlap, it is a good idea to specify colors of the native objects in RGB. The fact that Affinity apps cannot show RGB objects in full color gamut in CMYK mode makes this a bit inconvenient, especially since the color pickers display the color values always in the document color mode.

 

Wow! It would never have occurred to me that rasterizing a layer would produce a color change. It makes sense in a way since the placed object no longer has a color space from its own document. Still seems pretty weird, honestly. And I never would have found that little lock on the sliders, that definitely isn't something I'd expect to allow you to change to color mode of something with. Again, it makes sense in retrospect. I need to think for this document what we want to do. It's mainly for print but it wouldn't be the end of the world to keep it all in RGB for digital. That seems like it could be a lot of work, though. I don't know.

Thanks so, so much for your helpful videos!

[lacerto]

Obsolete.

[tetractys]

@lacerto Thank you for your detailed explanations. I've been pulling my hair out trying to figure out if my issue was intentional/standard or a bug. I didn't remember previous print projects looking so drastically different in PDF export (CMYK from the get-go, export as CMYK PDF) but I guess I was just using colors that were cross compatible in the past (whatever the proper terminology is there haha).

I have my business card project started in CMYK using US Coated SWOP v2, exported with PDF for Print using Document Color, all that jazz, and the preview window is WAYYYY off. It's not actually stated anywhere that I could find online—be it Affinity docs, guides, random Youtube vids, posts on Reddit and on Affinity Forum—that the Export Preview window is supposed to be off. I feel like I have a superpower for being able to find myself in weird edge cases, esoteric bugs/quirks, or just between-the-lines presumed knowledge that's never stated with any software, OS, or tool I use. It's maddening.

Not trying to redirect or resurrect someone else's thread, just wanted to say thanks because I was in the same situation.

[Walter Nissen]

16 minutes ago, tetractys said:

@lacerto Thank you for your detailed explanations. I've been pulling my hair out trying to figure out if my issue was intentional/standard or a bug. I didn't remember previous print projects looking so drastically different in PDF export (CMYK from the get-go, export as CMYK PDF) but I guess I was just using colors that were cross compatible in the past (whatever the proper terminology is there haha).

I have my business card project started in CMYK using US Coated SWOP v2, exported with PDF for Print using Document Color, all that jazz, and the preview window is WAYYYY off. It's not actually stated anywhere that I could find online—be it Affinity docs, guides, random Youtube vids, posts on Reddit and on Affinity Forum—that the Export Preview window is supposed to be off. I feel like I have a superpower for being able to find myself in weird edge cases, esoteric bugs/quirks, or just between-the-lines presumed knowledge that's never stated with any software, OS, or tool I use. It's maddening.

Not trying to redirect or resurrect someone else's thread, just wanted to say thanks because I was in the same situation.

Please don't worry about resurrecting the thread, I'm glad to hear that someone else was confused. My document did come out looking great with the help I received.