Here's Ye Olde Schoole Methode.
Make an empty layer above the image.
Set up the rubber stamp with a nicely sized circle with a feather edge, more or less the default.
Make sure "Aligned" and "Current & Below" are selected at the top of the screen.
Switch to the new layer.
Take a rubber stamp sample at the horizon line more or less between the vertical squiggles I drew. Note how you see a sumperimposition, move the stamp tool up and down to match the horizons, like I almost did.
Stamp over the bad area at the right with the OK area between the squiggles just to the left. Note that the stamping goes ONLY on to the new layer, without messing up your original layer. File that away in the your head, layers are important.
Problem...the new area is too light.
Add a "Curves" layer above the stamped layer. I made a red arrow pointing to a symbol under the curves graph. If you click it so that it looks that way, the curves layer will only affect the layer right underneath it. Also remember that you will have to undo that in case you want a curves layer that affects everything under it...that could make you crazy later if you don't know what's going on.
Now pull down the contrast as indicated, and you're there. Only the stamped layer is affected.
And if you're still not there, just toss the rubber stamped layer and try again.
Total time to do all this...less than 1 minute when you're up to speed. And no layers were harmed in the making of this fix!
You can also do this by just copying the image onto a new layer on top of the old one, shifting it to the right, and masking out the parts you don't want. But rubber stamping is more fun and makes a smaller overall file, I think.
