Effects and transitions

Difference Matte effect

The Difference Matte effect creates transparency by comparing a source clip with a difference clip, and then keying out pixels in the source image that match both the position and color in the difference image. Typically, it’s used to key out a static background behind a moving object, which is then placed on a different background. Often the difference clip is simply a frame of background footage (before the moving object has entered the scene). For this reason, the Difference Matte effect is best used for scenes that have been shot with a stationary camera and an unmoving background. For more information on using the Difference Matte effect, watch the online training video on the Total Training website.

A B C D

Difference Matte effect

A. Original image B. Background image C. Image on second track D. Final composite image

Replace a static background with Difference Matte

The Difference Matte creates transparency by comparing a specified still image with a specified clip and then eliminating areas in the clip that match those in the image. This key can be used to create special effects. Depending on the clip, it’s possible to use Difference Matte to key out a static background and replace it with another still or moving image.

You can create the matte by saving a frame from a clip that shows the static background before the moving object enters the scene. For best results, neither the camera nor anything in the background should move.

The following Difference Matte settings are adjusted in the Effect Controls panel:

View Specifies whether the Program Monitor shows the Final Output, Source Only, or Matte Only.

Difference Layer Specifies the track to be used as the matte.

If Layer Sizes Differ Specifies whether to center the foreground image or stretch it to fit.

Matching Tolerance Specifies the degree to which the matte must match the foreground in order to be keyed.

Matching Softness Specifies the degree of softness at the edges of the matte.

Note: The RGB Difference Key uses color to define transparency much as the Difference Matte uses a still image.

Blur Before Difference Specifies the degree of blur added to the matte.

1Find a frame of your foreground clip that consists only of the static background. You will use this frame as a matte. Save this frame as an image file. It will appear in the Project panel.

2Drag the matte frame from the Project panel to a video track in a Timeline panel.

3Drag the clip you want to use as the background to a track in a Timeline panel above the matte frame.

4Place the video clip you wish to use in the foreground on a track in a Timeline panel above the background clip.

5(Optional) If you’re animating the Difference Matte over time, make sure that the current-time indicator is in the position you want. Click the Toggle Animation icons for the settings you adjust.

6In the Effects panel, expand the Video Effects bin and then the Keying bin.

7Drag the Difference Matte effect onto the foreground video clip.

8In the Effect Controls panel, click the triangle next to Difference Matte to expose its controls.

Last updated 1/16/2012

Effects and transitions

9From the Difference Layer drop-down menu, select the track that contains the matte frame.

10Adjust the other settings as needed to achieve the desired effect.

11(Optional) If you’re animating the Difference Matte, move the current-time indicator either in the Effect Controls panel or Timeline panel and change the Image Matte settings.

A new keyframe appears in the Effect Controls timeline when you change the settings. You can also adjust the interpolation between keyframes by editing the keyframe graph. Repeat this step as needed.

More Help topics

“Export a still image” on page 441

“Modify keyframe values” on page 420

Eight-Point, Four-Point, and Sixteen-Point Garbage Matte effects

The three Garbage Matte effects aid in cropping out extraneous portions of a shot so that you can apply and adjust a key effect more effectively. The mattes are applied with either four, eight, or 16 adjustment points for more detailed keying. Once you apply the effect, click the Transform icon next to the effect name in the Effect Controls panel. This displays the garbage matte handles in the Program Monitor. To adjust the matte, drag the handles in the Program Monitor or drag the controls in the Effect Controls panel.

Maxim Jago demonstrates animation of garbage mattes on the video2brain website.

Mask out objects with garbage mattes

Sometimes the subject of a scene is properly keyed except for undesired objects. Use a garbage matte to mask out those objects. Depending on the shape of the mask, you can use the Four-Point Garbage Matte, Eight-Point Garbage Matte, or Sixteen-Point Garbage Matte. More points let you define more complex mask shapes.

The Garbage Matte keying effect provides settings that represent the x and y pixel coordinates of each point of the garbage matte, measured from the top left corner of the frame. Changes appear in the Preview view of the Program Monitor.

The microphone (left) is masked out by repositioning image handles in the Preview view of the Program Monitor (center), creating a garbage matte that is then keyed and superimposed over a background (right).

1In a Timeline panel, place the clip you want to superimpose in a track above the one containing the background clip.

2In the Effects panel, click the triangle to expand the Video Effects bin and then click the triangle to expand the Keying bin.

3Drag either the Eight-Point Garbage Matte, the Four-Point Garbage Matte, or the Sixteen-Point Garbage Matte effect to the superimposed clip.

Your choice of garbage matte depends on the number of points needed for mask shape.

4In the Effect Controls panel, click the triangle next to the Garbage Matte name to expand the settings.

5(Optional) If you’re animating the Garbage Matte Key over time, make sure that the current-time indicator is in the position you want. Click the Toggle Animation icons for the position settings you plan to adjust.

Last updated 1/16/2012

Effects and transitions

6 Do any of the following to adjust the mask shape:

•With the Garbage Matte effect selected in the Effect Controls panel, drag the Garbage Matte handles in the Program Monitor.

•Adjust the Garbage Matte point settings in the Effect Controls panel to specify the size and position of the garbage matte.

7(Optional) If you’re animating the Garbage Matte Key, move the current-time indicator either in the Effect Controls panel or a Timeline panel and then change the Garbage Matte handle positions in the Program Monitor or adjust the settings in the Effect Controls panel.

A new keyframe appears in the Effect Controls timeline when you move the handles in the Program monitor or change the settings in the Effect Controls panel. You can also adjust the interpolation between keyframes by editing the keyframe graph. Repeat this step as needed.

More Help topics

“Modify keyframe values” on page 420

Image Matte Key effect

The Image Matte Key effect keys out areas of a clip’s image based on the luminance values of a still image clip, which serves as a matte. The transparent areas reveal the image produced by clips in lower tracks. You can specify any still image clip in the project to serve as the matte; it does not have to be in the sequence. To use a moving image as the matte, use the Track Matte Key effect instead.

Define transparent areas with Image Matte Key

The Image Matte Key determines transparent areas based on a matte image’s alpha channel or brightness values. To get the most predictable results, choose a grayscale image for your image matte, unless you want to alter colors in the clip. Any color in the image matte removes the same level of color from the clip you are keying. For example, white areas in the clip that correspond to red areas in the image matte appear blue-green (since white in an RGB image is composed of 100% red, 100% blue, and 100% green); because red also becomes transparent in the clip, only blue and green colors remain at their original values.

Note: You can use the Titler to create shapes and text to use as mattes.

A still image used as a matte (left) defines transparent areas in the superimposed clip (center), revealing background clip (right).

1Add the clip (used as a background) to a video track in a Timeline panel.

2Add the clip you want to superimpose to any track higher than the track containing the background clip. This is the clip revealed by the track matte.

Be sure the superimposed clip overlaps the background clip in a Timeline panel.

3In the Effects panel, click the triangle to expand the Video Effects bin and then click the triangle to expand the Keying bin.

4Drag the Image Matte Key to the superimposed clip in a Timeline panel.

5In a Timeline panel, select the superimposed clip.

Last updated 1/16/2012

Effects and transitions

6In the Effect Controls panel, click the triangle to expand the Image Matte Key settings.

7Click the Setup button , browse to the image being used as the matte, and then click Open to select the image.

8(Optional) If you’re animating the Image Matte Key over time, make sure that the current-time indicator is in the position you want. Click the Toggle Animation icons for the settings you adjust.

9Click the Composite Using menu and choose one of the following:

Matte Alpha Composites the clips using the alpha channel values of the image matte you selected in step 7.

Matte Luma Composites the clips using the luminance values of the image matte you selected in step 7.

10 (Optional) Select the Reverse option to swap the areas that are opaque and transparent.

11 (Optional) If you’re animating the Image Matte Key, move the current-time indicator either in the Effect Controls panel or Timeline panel and change the Image Matte Key settings.

A new keyframe appears in the Effect Controls timeline when you change the settings. Repeat this step as needed. You can also adjust the interpolation between keyframes by editing the keyframe graph.

More Help topics

“Adding, navigating, and setting keyframes” on page 415

“Modify keyframe values” on page 420

Luma Key effect

The Luma Key effect keys out all the regions of a layer with a specified luminance or brightness.

Use this effect if the object from which you want to create a matte has a greatly different luminance value than its background. For example, if you want to create a matte for musical notes on a white background, you can key out the brighter values; the dark musical notes become the only opaque areas.

White background of original (top and left) is removed using the Luma Key effect and composited over underlying layer (right).

Adjust the following settings as necessary:

Threshold Specifies the range of darker values that are transparent. Higher values increase the range of transparency.

Cutoff Sets the opacity of nontransparent areas specified by the Threshold slider. Higher values increase transparency.

You can also use the Luma Key effect to key out light areas by setting Threshold to a low value and Cutoff to a high value.

Last updated 1/16/2012