Is there a website that has close-up pictures of minifigs?
Brickset.com has minifies entries for the majority of sets. here's an example. 

http://brickset.com/sets/60120-1

Click on the minifigs tab. Some are on a plain white background, some not.

There's also heaps on BrickLink.com

http://www.bricklink.com/catalogTree.asp?itemType=M