Showing figures from a paper in presentation I'm giving a talk summarizing someone else's paper and I'd like to show some figures from their paper during my presentation.  It's an informal talk to fellow students and a few professors at my school.  Would it okay to just have a PDF of their paper up on the screen showing the figures needed?  Should I obtain permission before I do this?
In my field, mathematical physics, I've seen many presentations with figures from papers, and it's perfectly acceptable to do so providing you reference the work either at the end on a separate slide or as a footnote.

If the figure does not consist of data collected by the authors, but rather, for example, the graph of a function, then you could of course plot it yourself and include your own figure. There would be no need for citation.