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I just read a good book on DTP.

The autor stated, that one should not attach color ICC profiles to images placed in a publication (say when placing an image into InDesign document). The author doesn't explain this further unfortunately.

Can someone explain to me, why not attach ICC profiles to images placed in a publication, does it cause problems in production? And does this apply to PDF/X-1a only, or also to PDF/X-4 workflow? As far as I understand, PDF/X-1a is not color managed and PDF/X-4 is. I read somewhere, that the first doesn't allow ICC profiles, and the other does.

Still, from what I understand. An output ICC profile is allowed, but not per image ICC profile.

Can someone explain this to me? I'm confused enough.

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    The reasoning goes probably something like this: Do you really want each image being potentially a surprise. You have to understand that ICC profiles do not guarantee that the transformation is what you want. So having only one profile reduces wok to check for surprises. Also how many profiles do you really need.
    – joojaa
    Apr 10 '20 at 9:54
  • Yup. They want you to do the work, not them. By converting all import profiles at some point before final export, you get to check for any colour issues.
    – Tetsujin
    Apr 10 '20 at 11:43
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That is a truth with some modifications. It all depends on your workflow.

Why would you even want to make a document with several different CMYK profiles? I can only see one specific use for that (more about that later). When a print house print your file they can only adhere to one color profile. They can't take several different CMYK profiles into account. Mostly it's your own responsibility to use the correct CMYK profile.

Our print house and the other print houses I send files to just use the CMYK values of your document. They don't convert anything. You have converted your files to CMYK, ideally using the recommended color profile, and that's the values which are printed. At that point color profiles doesn't matter anymore. The color profiles is a tool used by you to obtain the correct CMYK values.

There are many different imaginable workflows. I mostly use one these three:

  1. For standard everyday projects I simply edit all my images in RGB and place them as such in InDesign. While working on the document I make sure to softproof using the correct color profile and on export I export the images to that profile. With this method it's very important for the images to have their RGB profile attached. If they come from multiple sources they probably have a mix of Adobe RGB, sRGB and other profiles. If they are placed as untagged RGB they all get converted as if they had the RGB color profile of your document. This will lead to unexpected colors.

  2. In some rare cases like an art poster, I might want to convert my images to the correct CMYK profile in Photoshop and do some editing in CMYK. In that case I convert all the images to the same correct CMYK profile, which is the same as specified in my InDesign document. Whether or not the profiles is attached doesn't make any difference.

  3. Sometimes I need to use two different CMYK profiles, one for ordinary color images and one for 4-color black and white images. In that case I can either manually convert all the images to these two profiles, or I can just convert all of the images of one of the two types manually and convert the rest on export, leaving the manually converted images unaltered. In this case I don't attach a profile to the manually converted images since i don't want InDesign to convert them to another CMYK profile. Again it doesn't really matter which name the profile of the individual images has. The print house just prints according to the color profile they use and simply uses the CMYK values of my images.

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  • All this makes sense to me. I have one sub-question. I started using Affinity Publisher and on export to PDF/X-1a, X-3 and X-4 the option Embed ICC Profiles is ticked on by default and locked. Therefore all images converted to CMYK on export, have the ICC Profile attached, which is the same as the Output Intent ICC Profile. Do I have to strip down all the image profiles in software such as PDFToolbox? So that they are DeviceCMYK or is it not a problem at all?
    – Aardo
    Apr 10 '20 at 14:32
  • After creating your final PDF? I can't see why this should be necessary because it's going to be the same CMYK values, but without a color profile name attached. Maintaining the Output Intent name is good I guess, because it makes it possible for the print shop to see which profile you used and warn you if it's wrong. But ask the print shop if you are in doubt.
    – Wolff
    Apr 10 '20 at 14:35

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