If you’d like to use a mask on a layer, the first step is to add one. This approach is most useful when you want to globally mask parts of an image layer or to blend several filters at once. This mask can be edited using the Brush, Radial Mask, or Gradient Mask tools.
To add a mask:
Select the desired layer. By default, layers and adjustment layers have no mask.
Click the Edit Mask button.
Choose one of the four mask types
Brush
Radial Mask
Gradient Mask
Luminosity
These tools offer several controls, we’ll explore them next.