Updated: 06/07/2019 by Computer Hope
Illustration: A composite image created from two source images and an alpha channel.

A compositor is a person who combines video data from multiple sources into a single video. This process is carried out using software such as Adobe After Effects, Final Cut Pro, or Adobe Premiere. The video sources are layered using transparency information to determine which pixels from each layer appears in the final result.

Compositing terms

Transparency information is called a mask. It can be defined by vectors (lines and points), which create a closed shape. Parts of the image are concealed, depending on whether they are inside or outside the shape.

A mask can also be defined by grayscale pixels, called an alpha channel. The brightness of each pixel in the alpha channel dictates the transparency of the corresponding pixel in the source image.

In traditional filmmaking, the layer that masks out parts of a source image is called a matte. If the edges of the matte are not crisply defined, permitting a gradient of partial transparency, it is called a feathered matte. If the mask changes position or shape from frame to frame, it is called a traveling matte. These terms are still sometimes used in digital video compositing.

The image or video which results from the compositing process is called a composite.

Animation, Clone stamp tool (Photoshop), Color depth, Nonlinear video editing, Software terms