This questions is not directly related to Matter Modeling, but it is related with the way we share/publish our research.
Let suppose that someone deposited a manuscript in a preprint server. Then, he/she send the same manuscript to a Journal and it is accepted. In many journals you have to sign a copyright transfer given the journal the publication/reproduction rights over the whole manuscript (text and images).
Now, I, as a reader, get access to both, the preprint and the final published paper.
The question is: Can I just use any of the images from the work in my own paper (just as reference, comparison, etc.) citing the source? Isn't there a superposition of rights?