A matte is a mask or shape used to define which areas of a video frame are visible, hidden, or partially transparent, enabling selective compositing and effects application.
In video compositing, a matte is essentially a grayscale image that controls visibility. White areas of the matte are fully visible, black areas are fully hidden, and gray areas are partially transparent. Mattes are used to isolate specific parts of an image — for example, separating a person from their background, revealing text through a shape, or applying an effect to only a portion of the frame.
Mattes come in several forms. A garbage matte is a rough shape drawn to exclude unwanted areas from a composite. A luma matte uses the brightness values of one layer to control the transparency of another. A track matte uses the shape or luminance of a dedicated layer as a transparency mask. Rotoscoped mattes are painstakingly hand-drawn frame by frame to isolate complex subjects with precision.
Understanding mattes is helpful when requesting specific visual effects. If you want a video that shows footage playing inside the shape of your logo, that requires a matte. If you need a person extracted from one environment and placed in another, that involves creating a precise matte around the subject. Mattes are one of the most fundamental tools in visual effects, and their quality directly determines how convincing the final composite appears.
An alpha channel is an additional data channel in a video or image file that stores transparency information, allowing portions of the frame to be fully or partially transparent.
Compositing is the process of combining visual elements from multiple sources — live-action footage, CGI, graphics, and effects — into a single, unified image that appears as though everything was captured together.
Rotoscoping is the frame-by-frame process of manually tracing around elements in video footage to create precise mattes for isolation, compositing, or effect application.