I pull the levers in Aperture 3 adjusts the levels and other common things. But some of the most important thing is to remove color and then adjust the white balance before I put the colors back into the program. In Aperture, so I adjust on with auto levels again. But this is difficult to explain in that I have created a template that I just click on and then the alignment is done in the program. Hope you got a little wiser with this explanation