Halos appear after processing an image, especially if you have blended multiple exposures. It is also more commonly an artifact of sharpening an image, and not a result of you processing. There are several ways of removing them, however this is the way I do it. Its completely non-destructive and can be deleted if needed.
1) In Photoshop, open a new blank layer.
2) Change the blend mode to darken.
3) Using a clone stamp tool, clone out the halo with a better color.
4) Done
