Designer: Weird color behaviour when exporting to PDF

[David Still]

I have the latest version of Affinity Designer on Win10.

In a CMYK document with both vector and raster elements, I want all elements to have the same color. The raster elements are designs I have drawn with ink on paper, scanned, made the background transparent, saved as PNG and Placed in the Designer document.

In order to give them the color I want, I have tried two methods: one is to make a square shape with the right color, and the transparent PNG as a clipping mask to the shape (or vice versa, I'm unsure of clipping mask terminology), the other is to simply apply a color overlay effect on the PNG object. Both methods produce identical results.

The problem comes when I export the file to PDF. I expect some colors to shift a bit when viewing the PDF in Acrobat Reader or the preview window of my file browsers, since neither program is color managed. But in the case of the raster elements, the color shift is extreme, while the vector object shifts only a little, even though they're defined as exactly the same color in Designer.

When troubleshooting and trying to replicate this problem, I figured this isn't actually that big a problem, since the CMYK values seem to be unchanged. When opening the PDF in Publisher, the colors are correct again, and when we did a test print run, the colors printed correctly.

The problem seems to be the conversion between RGB and CMYK values; since RGB is a wider gamut, the colors look good when viewed in CMYK, but garish in RGB.  I found a workaround: if I edit my colours with the CMYK sliders, and enter the exact same numbers that were already there, the RGB values will be converted to more sensible numbers, that are inside the CMYK gamut.

So the problem I'm posting about is practically solved by this workaround, but it's still impractical to have to go through all my files to find the misbehaving colors and re-enter their CMYK values. Even though the garish colors will print correctly, they will display incorrectly when my client views them in Acrobat, and it's not very professional of me to submit work and have to say "just trust me on the colors".

And the fact that within the same document, objects with identical color values will export differently depending on whether they are vector or raster, seems bizarre to me. Does anyone know what's going on here?

Attached is the .afdesign document, the resulting PDF, and a jpg summary of what's happening. In the left column, I have used the color wheel to pick an arbitrary color; in the right column I have corrected that color by manually entering the CMYK values.

2021-0920-Af Color tests-01.afdesign 2021-0920-Af color tests-03.pdf

[DWright]

Can you please let me know the export settings that you are using as I am not getting the same export results when I use the for Print or Export PDF presets

2021-0920-Af Color tests-01.pdf

[David Still]

This happens on both the default presets for PDF (press ready) and PDF (for print). The document color profile is CMYK FOGRA39, and the export settings are Color space: As document, and ICC profile: Use document profile.

My monitor is calibrated and profiled, meaning I have a color profile for the monitor installed at the OS level. On the one hand, I don't think this makes a difference, as Acrobat (as far as I know) doesn't color manage, and also my client sees the same weird colors. On the other hand, color management is magic alchemy to me, so who knows what happens!

[Joachim_L]

3 minutes ago, David Still said:

so who knows what happens!

If the Resource Manager is reporting correctly although the images are missing. The Colour Space of the images is CMYK, but they have a RGB ICC profile, which makes no sense and is IMHO technically wrong. Use the correct ICC profile with the images and it should work.

[David Still]

Hm.. That's interesting. It seems PNG and CMYK aren't compatible, so I can't save a CMYK PNG, but I can replace the image with en embedded PSD, in CMYK. That fixes the issue.

Still, strange that the exported file contains elements in both color spaces? I thought the entire document could only be one or the other.

But it's funny how I've been searching among the export settings for anything to fix this issue, but not until I realized that there can be elements in different color spaces in one document did i see the checkbox "Convert image color spaces". Just checking that box, without replacing the PNG, also results in correct color in the output PDF! The filesize seems to go up, though...

So, three different fixes: manually input the CMYK values; replace PNGs with CMYK PSDs, or just check the box "Convert image color spaces".

Good grief, thank god for oil paints... Thank you both for the assistance!