About superimposing and transparency

Superimposing describes the process of overlaying and combining multiple images. Video clips are completely opaque by default, but superimposing them requires transparency. When you make clips on upper video tracks transparent, they reveal clips on the tracks below.

In Premiere Elements, you can quickly and easily make entire clips transparent by using the Opacity effect. In addition, you can apply any combination of opacity, masks, mattes, and keying to modify a file’s alpha channel, which defines the transparent areas in a clip. More advanced keying effects let you make specific colors or shapes transparent.

Note:

Titles you create in Premiere Elements automatically include an alpha channel. You can also import files with predefined transparent areas. Applications such as Adobe After Effects, Adobe Photoshop, Adobe Photoshop Elements, and Adobe Illustrator® can save transparency. Not only will the file have an alpha channel, but it will also conform to your project settings. See the respective user guides for information on saving files with transparency.

Premiere Elements uses the following transparency terms:

Alpha channel

A channel that defines transparent areas for a clip. This invisible channel exists in addition to the visible Red, Blue, and Green (RGB) color channels.

Opacity

A setting that determines how opaque or transparent a clip is. (For example, 75% opacity equals 25% transparency.)

Lowering opacity of upper video clip (left) reveals lower video clip (center), combining the two images (right)

Mask

Sometimes used as another word for alpha channel; also describes the process of modifying an alpha channel.

Separated Red, Green, and Blue color channels (left); the alpha channel or mask (center), and all channels viewed together (right)

Matte

A file or channel that defines the transparent areas of a clip. The matte determines the level of transparency in the resulting image. In Premiere Elements, you use mattes in conjunction with the Track Matte Key.

Matte (left) defines transparent areas in upper clip (center), revealing lower clip (right)

Keying

Defining transparent areas with a particular color (color key) or brightness value (luminance key). Pixels matching the key become transparent. Keying is commonly used to replace a uniform background, such as a blue screen, with another image. (In TV, for example, blue screens behind weather reporters are replaced with weather maps.) The Videomerge effect uses keying to automatically define the primary background color as transparent.

Replacing a background color with another image

A. Upper clip B. Blue Screen Key effect defines transparent areas C. Lower clip D. Combined clips 

Adjust opacity

By default, clips appear at full (100%) opacity, obscuring any clips on the tracks below. To reveal lower clips, simply specify an opacity value below 100%. At 0% opacity, a clip is completely transparent. If no clips are below a transparent clip, the movie’s black background becomes visible.

  1. Click the Applied Effects button to open the Applied Effects panel.
  2. Select the clip you want to make transparent, and do one of the following:
    • In the Applied Effects panel, expand the Opacity effect and drag the Clip Opacity slider to the desired value.

    • In the Expert view timeline, choose Opacity > Opacity from the pop‑up menu just above the clip. (You may need to zoom in to see this menu.) Click the Selection tool, position it over the clip’s Opacity graph, and when the pointer becomes a double‑arrow icon, drag the Opacity graph up or down.

    Creating transparency in the Expert view timeline

    Note:

    To fade a clip in or out over time, animate its opacity. If you simply want to fade to black, click the Fade In or Fade Out option in the Applied Effects panel. You can also create transparency by using keying effects.

Keying out color

To make specific areas in a clip transparent, apply a keying effect based on color, matte, or alpha channel. Pixels that match the specified key become transparent.

Color‑based keying effects

(Videomerge, Blue Screen Key, Chroma Key, Green Screen Key, and Non Red Key) Add transparency wherever a particular color occurs in a clip. For example, you can use color‑based keying effects to remove a background with a uniform color, such as a blue screen.

Matte‑based keying effects

(Four‑, Eight‑, and Sixteen‑Point Garbage Matte Keys, and Track Matte Key) Let you mask out areas of a clip with another clip or with areas you specify manually. You can add transparency according to the shape of a mask you position in the clip, or according to the grayscale tones in a file that you use as a matte. You can also use the Track Matte Key effect to make creative composites.

Alpha channel‑based keying effect

The Alpha Adjust Key effect lets you invert or turn off a clip’s alpha channel or convert areas without transparency to a mask.

Note:

For more information about keying out colors, see Help.

Create transparency with Videomerge

To automatically create transparency in the background of a clip, apply the Videomerge effect. This effect makes superimposing clips easy.

  1. In the Quick view timeline or the Expert view timeline, right-click/ctrl-click the clip you want to make transparent, and choose Apply Videomerge. (You can also choose Videomerge from the Effects panel.)

    The effect automatically detects the background color and removes it, making underlying clips visible through the transparent areas.

  2. (Optional) Click the Applied Effects button to open the Applied Effects panel, and expand the effect name to view and edit the effect’s options.
    Videomerge effect

    A. Foreground clip with colored background B. Background automatically made transparent with Videomerge effect C. Background clip that will show through transparency D. Combined clips 

    Note:

    On Mac OS, the Videomerge dialog is not displayed when you drag a clip with a solid background. To apply Videomerge on Mac OS, drag the clip to the Monitor panel, and then select the Videomerge option. You can also apply Videomerge from the Effects panel.

Create transparency with a keying effect

To create transparency wherever a specific color occurs in a clip, apply a color‑based keying effect. These effects are commonly used to remove a colored background.

  1. In the Action bar, click Effects to display the Effects panel.
  2. Choose a Keying effect (or Chroma, Blue Screen, Green Screen, or Non Red).
  3. Drag the effect to a clip in the Quick view timeline or the Expert view timeline.
  4. (Optional) Click the Applied Effects button to open the Applied Effects panel, and expand the effect name to view and edit the effect’s options.
    Replacing a background color with another image

    A. Upper clip B. Blue Screen automatically makes the background transparent C. Lower clip D. Combined clips 

Create transparency with the Track Matte Key effect

  1. If you haven’t already done so, add the matte file to the project: Click Add Media and choose Files And Folders. Navigate to the matte file, and click Open. The matte file should preferably contain only a single shape (for example, a star or a flower).
  2. Add a background clip to a track in the Expert view timeline.
  3. Add the clip you want to superimpose over the background clip to any track higher than the background clip. This is the clip revealed by the track matte.
  4. On a third track, add the clip that serves as the matte. (To add a third track, drag the matte to an empty area in the Expert view timeline above the highest video track. A new track is automatically created.)
  5. In the Effects panel, expand the Keying category folder, and drag the Track Matte Key effect to the superimposed clip (the clip above the background clip).
  6. Click the Applied Effects button to open the Applied Effects panel.
  7. In the Applied Effects panel, expand the Track Matte Key.
  8. For Matte, choose the video track that contains the matte.
  9. Adjust options as needed:

    Composite Using

    Select Matte Alpha to composite using the values in the alpha channel of the track matte. Select Matte Luma to composite using the image’s luminance values instead.

    Reverse

    Inverts the values of the track matte.

    Tip: To retain the original colors in the superimposed clip, use a grayscale image for the matte. Any color in the matte removes the same level of color from the superimposed clip.

Hide unwanted objects with a garbage matte

Sometimes a color‑based keying effect properly removes a background, but undesired objects still appear, such as a microphone or cable. Use a garbage matte keying effect to mask out those objects. Garbage mattes work well for areas that have clearly defined boundaries but no uniform color to key. Garbage mattes also work well to clean up unwanted artifacts that a color‑based keying effect left behind.

Unwanted background (left) is masked out by reshaping the Four‑Point Garbage Matte in the Monitor panel; then the Green Screen Key effect is applied (center) to superimpose the boy over the underlying track (right).

  1. Place a clip in a track.
  2. In the Effects panel, expand the Keying category, and drag a garbage matte effect to the clip.
  3. Click the Applied Effects button to open the Applied Effects panel.
  4. In the Applied Effects panel, click the triangle next to the effect’s name to expand it.

    Note:

    The name of each garbage matte effect reflects the number of handles it provides: Four‑Point Garbage Matte, Eight‑Point Garbage Matte, and Sixteen‑Point Garbage Matte.

  5. Do one of the following to reshape the matte:
    • Click the effect name to display the garbage matte effect’s point handles in the Monitor panel, and drag the handles.

    • Change the garbage matte effect’s values in the Applied Effects panel.

Invert or hide alpha channels

You can use the Interpret Footage command to change how Premiere Elements interprets a clip’s alpha channel throughout a project.

Note:

To ignore or invert the alpha channel of only a single instance of the clip, apply the Alpha Adjust keying effect instead.

  1. Select a clip in the Project Assets panel.
  2. Choose File > Interpret Footage, specify Alpha Channel options as needed, and click OK.

    Ignore Alpha Channel

    Ignores the alpha channel included with the clip.

    Invert Alpha Channel

    Reverses the light and dark areas of the alpha channel, which reverses the transparent and opaque areas of the clip.

    Tip: If you have difficulty identifying which parts of a clip are transparent, temporarily add a bright color matte on a track below the image you are keying. (See Create a colored matte for a background.)

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