I'm attempting to change the density (using curves) of this underexposed piece of film. (8bit,500+mb file, in cs4) I'd like to make adjustments to the top and bottom portions of the image independently. If I use the box tool with a feather of 15-25 pixels, I get some evidence of the correction (lighter sky) when adjusting the bottom half. Also, the horizon isn't perfectly flat due to lens distortion (i guess) and some tiny distant islands on the right so there's that to deal with. What's the easiest way to go about it? All that said, I'm pretty much a 3rd grade* level photoshop user so please keep any suggestions as simple as possible.
*third graders are probably more knowledgeable than myself, actually.