The gradient allows you to create a region of softness around the mask edge. It applies a gradient according to the distance of the borders from the mask spline. You can create a uniform gradient or customize it at different parts of the mask. The gradient can have two softness borders, one inside and one outside the mask edge.
To add a gradient to a mask:
From the Tools box, change the mode to Add Points.
Hold down Shift and drag away from the spline.
Click on the mask spline.
(Optional) Do one of the following:
The position and distance of a gradient point from the mask spline can be controlled gesturally in Select mode, or in the Gradient tab.