The value of a brush attribute depends on the selected attribute mode. You can choose Constant, Off, Front, Back, Result, Saved, Pressure, or Direction.
(a) Brush Attribute fields (b) Attribute Mode controls
In Constant mode, the brush attribute values remain constant. In Off mode, the attribute is disabled.
The Front, Back, Result, and Saved modes use the colour values in a reference image to vary the brush attribute value. Pressure and Direction modes affect how paint is applied by causing the brush attribute value to vary in relation to the pressure exerted on the pen and the direction of the brush, respectively.
Note: Do not set the Size, Rate, or Pressure attributes to Off mode.