Sometimes I have shots that are not well exposed (I shoot in RAW) and it's really dark. I would selectively brighten up the shadow area.
Usually it's fine if the area is not too dark. But if it's really dark (imagine an incorrectly exposed image, exposed for the window and the person inside has a silhouette) the color becomes weird when brightened up. A person skin would look green. And it's really difficult to correct. In fact, using the white balance tool doesn't even fix it. I have to manually tweek the color curves (red green blue) and it's impossible to get it back to looking like normal skin.
Why does this happen and how do I fix it?