I have a painting that I photographed. There's a lot of empty canvas (the painting is actually on paper). That canvas is off white -- and very dirty. It shows up in the photo. I can remove the crease marks, but the amount of dirt on the painting' surface makes the canvas look blotchy. I'd like to even out this background. I can remove the subject (flowers) from the background easily so that I have a layer of canvas only, but I'm not sure the best way to even out the background. Does anyone have a suggestion? I have attached a section that shows the dirty surface.
If you can increase the brightneess and play with contrast you may be able to get a clear pictures then just remove the Blank Area by making a selection from the Mgic Wand and deleting it.