When publishing in a non-open access journal, one (Author) is usually required to sign a copyright transfer agreement with the Publisher such as this.
Now, when the paper includes some work, say a photo, by a third party XYZ, obtainable under a CC license and properly noted ("Photo by XYZ, licensed under CC BY-ND 4.0"), I assume that it is understood that this is not part of the transfer, but Author assures the Publisher that Author and Publisher actually have the permission to use it. (Since the CC license is non-exclusive, distribution of the article by Publisher will then be business between Publisher and XYZ, right?)
If that understanding is correct, now my actual question: what happens if Author and XYZ are identical? Say Author has produced some photo, and previously posted it somewhere under a CC license. They then reuse the photo in their own paper, with the same kind of attribution ("Photo by Author, licensed under CC BY-ND 4.0").
Author in this case actually holds the copyright to the photo, and it looks like they are in a position to transfer it, which they cannot escape from when signing the (unmodified) agreement. At the same time, it seems to me that this transfer does not work -- there are previous rights granted to everyone else! Can Author in this case (implicitely) transfer the copyright of the rest of the work, and independently grant usage rights for the photo throught the pre-exising CC license?
And even worse: suppose the work in question is not just an arbitrary photo, but depicts something obviously specific to the paper (say, photography of experimental setup, or a diagram relating to the research). In such a case, if Author dutyfully adds a copyright notice, they practically reveal their identity to the reviewers! How is this case resolved?
Background: I'm new to academic publishing and was a bit appaled when I saw what kind of copyright transfer agreements I am supposed to sign. I came up with this idea to at least be able to CC license my diagrams, and was wondering how much sense it makes. Related to this question, but not the same.