Today’s Question: In Photoshop how can I create a mask that is the opposite of an existing mask? For example, I’ve created a mask for a bird in flight, but now I want to apply different adjustments only to the sky. Can I duplicate an inverted copy of the bird mask?
Tim’s Quick Answer: Yes, you can use an existing layer mask in Photoshop as the basis of a new mask that is the opposite, such as for a mask for a subject versus the background. One option is to load a selection based on the mask, invert that selection, and then create the new mask based on that inverted selection.
More Detail: There are (of course) multiple ways you can approach just about any task in Photoshop, and creating an inverted copy of a mask is no different.
The approach I tend to use is to load a selection based on the existing mask, invert it, and then create the new mask. To do so, you can hold the Ctrl key on Windows or the Command key on Macintosh while clicking on the applicable layer mask on the Layers panel. This will load a selection based on that mask.
You can then invert the selection by choosing Select > Inverse from the menu. This selection represents the opposite of the mask you originally loaded as a selection. You can then create the new layer mask based on the current selection, either by creating a new adjustment layer that will have a mask matching the current selection automatically, or by selecting an image layer or layer group and clicking the “Add Layer Mask” button (the circle in a rectangle icon) at the bottom of the Layers panel.
