I managed to accomplish this in Photoshop a few months ago and I'm stumped trying to reproduce the steps. Basically I have a photo that I want to lighten just the face. I had found some steps on the web to accomplish this by using a clipping mask to grab just the skin and apply brightness, curves and or levels adjustment layers. The link to the article is no longer available on the web.
All I need to do is duplicate the background layer then using the knife tool make a path that only includes the face. I can get to this point. What I'm having a problem with is once the path has been selected ... I needs the steps to make that selection a clipping mask so I can play with various adjustment layers on just the face.
Any help will be appreciated.