publications - How to legally re-use images in paper and still continue to use and distribute them in slides?

I have created several figures that are a part of presentation slides. As usual for presentation slides, those were not published in any official proceedings (just the underlying paper, that didn't contain the same figures, was), and no copyright for the presentation slides or any parts thereof was transferred to any other party.

I have made the presentation slides available on my website and I would like to keep it that way. More generally spoken, I would like to continue being able to provide these slides whereever I wish, including allowing other people to redistribute them on their websites.

Now, I would like to re-use some of the figures from the slides in an upcoming paper, which will be published by Springer. Consequently, I will have to transfer copyright for the paper to Springer.

How do I safely re-use my graphics?

• As suggested by DCTLib's answer, publisher may wish that I cite the paper in all works that share a graphic with the paper. However, this does not seem feasible in cases where the final form of the presentation slides was created and distributed before the paper was even planned.


• Do I have to transfer copyright of these graphics, as they form a part of my paper, which means I am forced to remove the presentation slides, which would - after the transfer - constitute a possible copyright infringement?


• Do I have to somehow explicitly mark the respective graphics (in the paper and/or elsewhere - is there another place where I need to indicate that toward Springer?) as cited with permission (albeit I granted that permission myself) rather than original works first published in the paper?
  
  
  
  • Bonus sub-question: In this latter case, it seems that regularly publishing all created graphics on my website and then marking all graphics that I use in papers as cited from that website would save me and others lots of possible trouble when it comes to the future re-use of graphics that were already shown in papers whose copyright has been transferred to a publisher. It just cannot be so easy, as otherwise, everyone would be doing it, so there must be some catch in this plan (?)
  
  
  
  

Maybe more generally, the question could be put as: How can I re-use a graphic in a publication, if I have to transfer the copyright for the publication to a publisher, without changing the previously valid copyright/licensing status of the graphic?

I feel this must be related to the case when I want to use images that are already subject to a different license, e.g. a CC-SA license, and thus I cannot grant any publisher the exclusive right to publish these images, as that would conflict with the way the images are already in use and circulating.

Related Work

I have found various related questions, but they either deal with special permissions for re-use in theses, or with re-using images already published in copyright-transferred papers. Moreover, copyright laws in my country do not have a concept of fair use, so questions related to fair use are not applicable to the described scenario, either.

Background

I am asking this question in response to an urgent university-wide e-mail sent by university administration that asked us to take great care when it comes to copyright issues with respect to what we publish on university websites, or in the name of the university. Apparently, there has been a recent copyright-based legal issue for the university based on what some employees put on their websites, which did not end well for the university. While I do not know any specifics other than that the university had to deal with the receipt of one or more Abmahnungen, the tone of the e-mail made it clear that "acting in a way that will probably not create any problems" is not good enough.

EDIT: To be clear, I am not asking how to re-use a graphic that has already been published by one of the usual publishers and that is thus subject to the copyright restrictions of that publisher. I am asking about the opposite direction; how to have one of the usual publishers re-use a graphic I have already distributed before under less restrictive terms than what the publisher would allow, without the publisher assuming copyright ownership of the graphic.