There's more than one way to do it...
- You can use Quick Mask mode (hit "Q") and paint your masked area as desired. If you are painting gradients, make sure you have the gradient tool options set to go from black to transparent, not black to white.
- You use the "Smart Object" functionality to apply multiple filters to a selected area, and you can even modify the selected area, filter settings, and strength of application afterward. In order to use this, however, I'd suggest you get a good Ps book and read up on it.
- You can duplicate your image layer, add a layer mask, and run your filters on the duplicate layer. This is pretty simple, and also has the benefit of being able to modify the mask later. You cannot adjust filters later, however. This method is easy and relatively non-destructive. If you screw it up, delete the added layer and start over. |