MASKS AND MATTES

MASKS AND MATTESTransparency   Transparency (alpha, opacity) defines a pixel color’s

visibility

in a layer

Every element imported into AE contains an opacity channel

If an element does not have one, it adds a channel with solid (opaque – white) values

This channel can be changed for EVERY pixel using the Opacity

attribute with all layers: example: Opacity values 0% – 100%

MASKS AND MATTESMasks Rather than an attribute to control opacity for every pixel, we can select certain regions to reveal

When we “carve out” sections of opacity in a layer, we create what we term a “mask”

Masks can be created in a variety of ways

Ellipse or Rectangle tools

Pen Tool allows us to draw around an object to create a closed curve

Mask attributes added to layer:

Can keyframe mask shape, select mask, Animation->Create Mask keyframe (can also click on stopwatch next to Mask shape)

Move to another frame, reshape, automatically saves keyframe

MASKS AND MATTESMatteMatting

We can also use an image (as opposed to selecting regions ourselves) to control areas of opacity

Such images are called mattes, grayscale images

We can create them using a variety of tools

A matte used with a movie is called a tracking matte

MASKS AND MATTESMatte examplesgrey scale images that will define transparency

MASKS AND MATTESIn labWe will work with both masks and mattes to see how they are

created or utilized in after effects.

We will import this image

images into after effects and

use the pen tool and a grey scale

image to define the regions of

transparency.