Masking is used for defining specific areas of a layer to remove or retain. This is a vital part of compositing and visual effects.

Masks cannot be added to 3D effect layers. These must first be made into composite shots and embedded.

Creating masks

Masks can only be created in composite shots. They cannot be used on the Editor sequence.

To create a mask you use the mask drawing tools. There are simple rectanglar and elliptical shapes as well as a freehand tool for drawing complex shapes.

To create a new mask you need to select a mask tool in the Viewer and a layer. The mask will then be added to the selected layer.

See the Mask drawing chapter in the Viewer section for details on each of the shapes.

Editing masks

Once a mask has been created it can be edited and customized.

Editing the shape

editing mask shape

If you want to make adjustments to the mask shape you can use the freehand shape tool.

With the freehand tool you can select any mask shape on the timeline or in the Controls panel to display its shape points on the Viewer.

Individual points can be clicked and dragged to change the shape. Curved points have additional controls for changing the curvature.

Clicking on a connecting line will add a new linear point. Clicking and dragging on a connecting line will add a new curved point.

Transforming the shape

mask transforming

Using the Select tool in the Viewer you can transform the mask shape in the same way you would the layer itself.

The currently selected mask on the timeline or in the Controls panel will also be selected in the Viewer, with a bounding box around the shape. This can be used to scale and position the shape without changing the shape.

To animate the mask over time you must have the Path property's keyframes enabled.

Mask properties

A mask's properties can be customized in the Controls panel or on the timeline.

Inverted - toggles whether the mask selection is inside or outside of your shape.
Blend - multiple mask shapes can be blended together in various ways for different results.
Path - if keyframing is turned on for this property the mask shape can then be animated over time.

You cannot add or remove mask points using keyframing. A mask shape will have the same number of points for its entire duration.

Opacity - adjusts the transparency of the mask.
Expansion - this can be used to contract or expand the mask without needing to change its shape or position.
Feather - there are three types of feathering, working from inside the mask shape, outside, or both. Which you use will depend on the specifics of your shot.
Feather strength - a stronger feather creates a softer edge to the mask.
Roundness - this is a useful way to change a linear shape into a curved shape without needing to alter the points.

RECAP Masks are an essential compositing tool. HitFilm gives you fine control over mask creation and editing.