I am working on a lager poster about science which will be on display in a museum and may be made available online. I intend to compile it using images from different sources. Some are own work, some are Wikimedia Common (Public domain or Creative Commons), others may be plots/graphics from (mostly historic) journal articles (they are usually not open access).
To my understanding, the use of these sources for non-profit/academic purposes is free if attributed correctly. However, I am unsure about the consequences of compiling or slightly modifying these works. Journals may have their own license policies but my understanding is that reuse for such purposes is generally accepted. In addition plots which represent measured data may not be protected, it seems.
Here are some of my concerns:
Using a Creative Commons image may require me to publish the whole work under the same Creative Commons license. I suppose that this is not ok with licenses/copyright policies that apply for plots or graphics from journal articles?
The different images should fit in the design of the whole. In order to achieve this I may need to make minor changes, like cropping the image or changing the background color. Will such modifications be ok with Public Domain licensed images and the ones from journals?
May the license of the whole work be determined by the fact that I am working for a public university (even though this sort of work is probably not described in my work contract, so it could be interpreted as work which I do in my spare time)?
Generally, are there some good online resources which explain the license issues and attribution of images for this kind of work?
Here are some links I know: