Best point in workflow for colour adjustments to RGB photos to be used in a CMYK document?

[lineweight]

I'm reasonably comfortable making adjustments to RGB images in Affinity Photo. And usually the images are for display on screen or maybe in within documents to be viewed online, so I don't need to worry about converting to CMYK.

Now however I am producing (in Affinity Publisher) some PDFs to be sent to a commercial printer, so the document is set up as CMYK.

These PDFs will contain multiple photos that I am placing into the Affinity Publisher document, and because all these photos will be alongside each other I will want to do some tweaking to colours to make them reasonably consistent. Plus there are some that are scanned where I'll want to remove bits of colour cast and so on.

My question is: where in my workflow should I make these colour adjustments?

a) Get them all as good as possible, editing them in Affinity Photo still in RGB, and then import them into the Publisher document (at which point I assume Affinity does some kind of conversion on them)?

or

b) Import them all as they are into the Publisher document, so the RGB to CMYK conversion has already happened, and then do my tweaking and adjusting?

If I use method (b) then when, say, I do a levels adjustment on the images, it all looks slightly different to what I'm used to, which is a little disconcerting but I'm not sure if I need to worry about it. But if there are no major downsides to that method, it's possibly what I'd prefer to do because it allows me to make the adjustments while the images are next to each other and in their final context.

[lineweight]

Can anyone give me any pointers here?

[henryanthony]

I would convert to CMYK as early in the process as possible.

[grunnvms]

This is what I would do.

If your work has to be printed on a commercial printer, get the CMYK colour profile for that printer, and add it to the profiles of Affinity. The document you are setting up in Publisher should be set up with this profile.

Do all the work on the photos in Affinity Photo, and when you're ready, convert the photo to CMYK using the colour profile of the printer (document > convert). You can see the result.  Now you can import the photos in publisher directly.

[lineweight]

Hmm, as I thought might happen, two conflicting opinions.

But I have asked the printer if they can recommend which profile I use and/or send me the one for their printer.

[lineweight]

1 hour ago, grunnvms said:

Do all the work on the photos in Affinity Photo, and when you're ready, convert the photo to CMYK using the colour profile of the printer (document > convert). You can see the result.  Now you can import the photos in publisher directly.

Can I ask why you'd do the adjustments before converting?

Would it not be better to see the final results of what I'm going to get, while I'm actually doing the adjustments?

Or is it that I can do the adjustments in RGB to get what I'd ideally like, and then leave the conversion process to give me the nearest best version within the limits of CMYK?