Options

See the Overlay & Appearance options.

Project Paint

Occlude
With Geometry occlusion active only exposed (not hidden by other mesh parts) pixels are affected. This also allows for 3D stencils to be used to mask out areas of the surface too.
Cull
With backface culling enabled you can only paint on the front side of faces.
Normal

Activates a view normal falloff which means that as faces point away from the view the brush strokes fade away to prevent harsh edges.

Angle
The normal angle at which the falloff begins.
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.
Bleed
Seam Bleed extends the paint beyond UV island bounds to avoid visual artifacts (like bleed for baking).
Dither
Amount of dithering when painting on 8 bit images.
Unified Settings

Brush options shared between the brush types.

Size, Color, Strength