Mask settings.

Stencil Mask

The mask can be deactivated by the checkbox in the header.

Stencil Image

Image used as a mask. See Data-Block Menu.

UV Layer

Allows you to select the UV layer for the mask image.

Display Color

Mask color in the viewport. See Color Picker.

Invert Stencil (black/white icon)

Inverts the mask.

Cavity Mask

Cavity masking means that the brush will be masked if there is a cavity or a hill on the mesh surface depending on the mesh options. The cavity algorithm is vertex-based.