About transparency

In video or film, transparency allows one clip to show through another, creating composites, transitions, or special effects. The opacity of a clip or portion of a clip determines its level of transparency. At 100% opacity, an image contains no transparency at all; at 0% opacity, the image is completely transparent, allowing other clips to show through. At other percentages, the image is partially transparent, allowing other underlying images to be visible at the same time. The brightness values of a clip's alpha channel, an additional grayscale or monochrome channel in an RGB image, also determine the clip's opacity.

Certain parts of clips can be made transparent using tools called keys. A key finds pixels in an image that match a specified color or brightness and makes those pixels transparent or semitransparent, depending on the type of key. This process is called keying, or keying out the color. Keys can also use a clip's alpha channel to create transparency.

You can create transparency in a clip only after you have placed it in a superimpose track. By default, each new project includes one superimpose track, called Video 2. You can add up to 97 superimpose tracks. See Adding, naming, and deleting tracks.

Superimposing and Compositing > About transparency

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