Here is a crop of a photo that I am working on with GIMP. I am trying to remove the black spot down at the bottom, but maintain the light and shading that is on the line just above it (which is a leg). If you see the line of the leg above the black blotch, there is a sort of gray gradient right along the edge. I am trying to make the blotch disappear and the repair to be inconspicuous.
The problem is that the very dark part from the black blotch leaves a dark line behind where it intersects with the leg and the arm.
I have tried cloning (moderate success, but very tedious to get just right)
I tried manually masking (not very good)
I’m wondering if there is some other trick, like with luminosity masks, or manipulating the minimum output values from the levels tool.