I see. I have another machine doing my (semi)final renders. Regarding comparison; I use Irfanview a lot. When a crop is done (I mainly work in screensize at first, or use another camera closer to the area I want to check), I hit PrintScreen, open Iview and hit CTRL+V (Iview can stay on top), crop the part, do another crop with different settings, and can directly compare changes. Same works for larger sized renders too, but then you have to really save the render and open it. I usually do that later on.