Introduction

Mask define a specific area in a clip that you want to blur, cover, highlight, apply effects, or color-correct. Mask can be drawn using the shape tool (ellipse, 4-point polygon) or pen tool.

Ellipse mask is for creating a circular or elliptical mask. 4-point polygon is for making squares, rectangles (anything with four straight sides). Free draw bezier is to create any custom shape with as many vertex points as needed.

Creating Mask

To create a mask using shape tools

  • Select the clip containing the area to mask in Timeline.
  • Open Effects panel, select the effect that you want to apply to the masked area.
  • Apply the selected effect to a clip by dragging the effect icon from the Effects panel to the clip.
  • Click Ellipse shape tool to create an Ellipse-shaped mask. Click Rectangle shape tool to create a rectangle-shaped mask.

With the pen tool, you’ll need to click to make your own shape. Follow below steps to create mask using Pen Tool

  • Select the Pen tool.
  • Position the Pen tool and click to define the first vertex point. The first segment you draw is not visible until you click a second vertex point.
  • Click again where you want the segment to end (Shift-click to constrain the angle of the segment to a multiple of 45°).
  • Continue clicking to set vertex points for additional straight segments.
  • To close the path, position the Pen tool over the first vertex point. A small circle appears next to the pen tool pointer. Click or drag to close the path.

Effects are constrained within the masked area, mask appears on the clip displayed in the Program Monitor.

Modifying Mask

To alter the shape of mask, follow below steps

  • Adjust its size, shape, and position by clicking on the vertex points and dragging them where you want.
  • To add a vertex, mouse over the border of your mask until a mouse with a plus (+) sign shows up.
  • Move entire mask by dragging from inside the shape.
  • To delete a vertex, mouse over the vertex and hold Command (Control ) until a minus (-) sign show up, then click.
  • To change a straight vertex to a bezier, hold Option (Alt) and click on the vertex.

Adjusting Mask Edges

In the Mask Effect Controls, below settings define mask appearance and help create amazing look.

  • Mask Feather (edge softness) : It is represented by a dotted line around the mask. It softens the edges of the mask, helping it blend in with the rest of footage.
  • Mask Opacity (transparency) : At a value of 100, mask is opaque and blocks out any underlying area of the layer. As you lower the opacity, more of the area under the mask becomes visible.
  • Mask Expansion (size) : It control how close to mask edge the footage is masked.

Tracking a Mask

Mask applied on object can automatically follow the object as it moves from one frame to another. Effect Controls panel displays controls for tracking the mask forward or backward. Ways to track the mask in the settings (wrench tool):

  • Position: Moves the mask’s position each frame.
  • Position And Rotation: Moves the mask’s position as well as rotates it.
  • Position, Scale, and Rotation: Moves the mask’s position, rotates it, and scales it as it moves.

Reference

Masking and tracking