Note that copyright covers expression, not ideas. It is tha specific image that you would give up copyright to, not the underlying data. And not to a different image based on that data. But, it needs to be sufficiently different. I'm surprised, though, that a publisher would care about copyright of posters.

Moreover, when you give up copyright to a publisher you normally get back a license for certain uses. Those uses might not include the right to republication other than in a dissertation. You need to investigate and understand that license, since it gives you some rights, but not all rights.

Note that copyright covers expression, not ideas (nearly everywhere, but laws differ). It is tha specific image that you would give up copyright to, not the underlying data. And not to a different image based on that data. But, it needs to be sufficiently different. I'm surprised, though, that a publisher would care about copyright of posters.

Moreover, when you give up copyright to a publisher you normally get back a license for certain uses. Those uses might not include the right to republication other than in a dissertation. You need to investigate and understand that license, since it gives you some rights, but not all rights. And, if necessary, you can ask the publisher for a more generous license.

Note also that a copyright owner controls publication of "derived works", hence the requirement that a new image be "sufficiently different". A bit subtle, of course. But (most jurisdictions) copyright is a civil law matter so it is up to the copyright owner to complain. One basis of complaint is that the infringing work reduces the "value" of the original, which seems unlikely here, though not impossible to imagine.