In the introductory chapter of my thesis, I've been surveying the previous work in my field. As part of this, I've used images from some of those publications and included them as Figures in my own thesis.
Occasionally, I have slightly edited them - for instance, changing the labelling.
I usually only use one image from each paper.
My understanding is that this falls under academic fair use, and I do not need permission from any of the publishers to re-use these images in my thesis.
Am I correct?
It is fairly easy to get permission using RightsLink with most publishers. Just fill out the form on the website and you get the licence immediately.
Bill Barth's comment is extremely important - fair use is a defence rather than a prophylactic and I for one don't want to be in a position of having to defend my use of Figures in a court of law.
Of course, it is extremely unlikely that any publisher would do such a thing, but my feeling is it's better to be safe than sorry.