I have a project in which I need to scan in an older 16 x 20 portrait photo and touch out a scratch. The original photo has some manual air brushing on it. The airbrushing is supposed to simulate the portrait background and starts out dark on the bottom and fades into the subject of the portrait. Unfortunately it doesn't match the background at all and looks awful. I would like to change it. I can copy the background to the bottom of the photo but I can not figure out how to create the faded airbrush look. please see the photo