Is it allowed to make pdf 'snapshots' of images included in copyrighted scientific articles to back up my answer (e.g. Biology or Cognitive Sciences SE)? At the risk to be verbally nuked - I have to say I have done this a few times. Advise on the legal aspects of uploading visual images of copyrighted material is welcomed. Obviously I am more than willing to remove any such snapshots from my existing answers when necessary.
EDIT: As a side note in response to comments: I do cite the image sources, with links and all (John Doe et al, 2010 + attached weblink to article on publisher's website when copyrighted and not available full-text online). So the authors of the article will likely be OK with me posting their images + citation, it's the publisher's copyright ownership that is of concern to me. Note that I obtain these articles from my uni library. So they are not freely available full text on the internet.
EDIT2: The question What is proper etiquette when someone posts copyrighted material? touches on my question, but deals with full-text artciles that someone else has made public, possibly infringing copyrights. My question is different, as it concerns reproduction and uploading image material to imgur by me, while citing the material properly. When I would publish such a snapshot in a journal, I typically have to ask approval from the publisher of the original article. My question now is: What does it mean when I upload copyrighted material to imgur?