The Compositing Mode button determines how the transparency in a video track is generated. Because lower tracks show through higher tracks, it is the compositing mode of the higher track that determines how much of the lower track shows though. The compositing mode of the lowest video track adjusts its transparency against the background.

The mode can be selected by clicking the Compositing Mode button and choosing a mode from the menu.

The following examples demonstrate how each of the compositing modes would affect two simple tracks. Track one is a generated media event with a transparent edge, and track two is a DV clip.

Mode	Description	Example
Multiply (Mask)	Merges the colors of the tracks.
Source Alpha	Uses the alpha channel to determine transparency. The compositing mode is based on the alpha channel characteristics of an event or media file. If no alpha channel is present, the Source Alpha mode has no effect.
Add	Combines the color values in the composite group.
Subtract	Subtracts the overlay color values from the background.
Cut	Cuts out the overlay color values from the background.
Screen	Multiplies the inverse of the overlay color values with the background color values. This makes overlay colors weaker and less present and results in a lighter video image. The opposite of this mode is Multiply.
Overlay	Heightens contrast by using Multiply mode on darker colors and Screen mode on lighter colors.
Hard Light	Adds overlay colors as if the overlay were lit by a bright, focused spotlight.
Dodge	Brightens the background based on the overlay color values.
Burn	Darkens the background based on the overlay color values.
Darken	Compares the overlay and background pixel by pixel and selects the darker color value for each pixel.
Lighten	Compares the overlay and background pixel by pixel and selects the lighter color value for each pixel.
Difference	Compares the overlay and background pixel by pixel and subtracts the darker color value from the lighter color to generate a new color value.
Difference Squared	Remaps color values along a parabolic curve. The color values of the layers in the composite group are subtracted, and then the subtracted values are squared. The resulting image will have less extreme changes in color values as the colors approach black (RGB 0,0,0) and more extreme changes in color values as colors approach white (RGB 255,255,255).

Drag the Level slider in a video track to control the transparency or blending of each track. Left is 100% transparent and right is 100% opaque. You can also double-click the percent to enter a specific numeric percentage

When you click the Parent Composite Mode or Compositing Mode  button and choose Custom from the menu, you can use plug-ins to customize compositing.

The included Displacement Map, Height Map, and Bump Map plug-ins can create interesting lens, mirror, water, fire, and other light-bending effects.