Steve's Tips
Using the Track Matte in Premiere Elements 2.0
In the world of digital imagery, including video, when you "matte" something, you create a mask around it. (Think of cutting a matte, or window, to fit inside a picture frame.) You render the area of your video frame outside the matte invisible (or, more accurately, transparent). A Track Matte uses a shape on another video track to define the matte area. And, as that shape follows a motion path created by keyframing, the matte moves with it, revealing on the area of the clip defined by that shape and then rendering the rest of the video frame transparent.
There are many uses for the tool. A common one is using it to hide or censor an area on a video — such as blurring the face of someone who refused to sign a waiver to appear on "COPS" or turning nudity or other offensive visuals into indecipherable pixels. Producing this effect with the Track Matte entails producing two versions of your clip — a blurred version on Video 2 and a clean version on Video 1 — and then using the Track Mattte and a geometric shape to define the area of your video frame that will show the blurred version (Track 2) and which will reveal (through the transparent area around the matte) the clean version of the video (Video 1).
Version 2 of Premiere Elements has greatly simplified the way the Track Matte tool is applied, as we’ll demonstrate in the walk-through for creating the blurred face effect below.
Click on the thumbnail images to see full-sized illustrations for this walk-through.
1. Duplicate your video clip
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Place the "master" clip to Video 2, then right-click the clip and choose Copy. From the menu at the top of the screen, choose Edit, Paste. A duplicate of the clip on Video 2 will appear on Video 1. (Note that Premiere Elements always pastes to Track 1.)
Line up both clips, one above the other as in the illustration to the right.
2. Apply the Mosaic Effect to the clip on Video 2
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The Mosaic effect is located on the Effects and Transitions panel, in the Video FX collection, in the Stylize category. (As an alternative, you can use the Blur effect from the Blur/Sharpen category.) Drag the effect onto the clip on Video 2, then click the triangle to the left of the effect in the Properties panel to reveal the control panel. Adjust the settings until your screen image is distorted beyond recognition.
3. Add a white dot graphic to Video 3
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You'll need a graphic of a white circle (or whatever shape best fits the area you want to blur — but, since the Track Matte uses levels of white to define the amount of opacity, the object must be pure white) with no background. This graphic can be created in Photoshop Elements, Paint Shop Pro, or whatever graphics program you are using. If you are using Photoshop Elements, delete the background layer so that, aside from the white circle, the graphic is completely transparent. In order to preserve this transparent background, you’ll need to save your graphics file as a Photoshop (PSD), TIF or PDF file. Use the Add Media button to add the graphic file to your project and then place the graphic on the Timeline on the Video 3 track, directly above the other two clips. Stretch its duration to match that of the other two clips, if necessary.
4. Create a motion path for the dot to define the matte’s position and motion track
The object you are trying to blur will most likely be moving around in your video frame, so you will have to set up a motion path for the white dot (so that it continues to "block" the object you are trying to obscure). (If the timeline isn't visible in the Properties panel, click the Show Keyframes button.) Click the triangle to the left of the Motion listing to reveal the control panel for this property.
Position the CTI at the beginning of your clip. Click the white dot in the Monitor and drag it so that it covers the area you want to blur. Use the Scale and Position settings to cover the spot you want to blur. When the dot is in position and scaled, click the stopwatch icon (technically the "animation toggle") to the right of the Motion listing to begin your keyframing session. A column of little keyframe diamonds appears, defining the opening keyframes for your motion path.
Move the CTI to the end of the clip and reposition the dot so it again covers the area you want to blur. As you do, new keyframe points will be automatically added. Move the CTI along the clip to check that the dot is tracking with the person or object you are trying to blur. Set up additional keyframes as needed to track with these positions (so the dot continues to obscure the portion of the image you want to blur). The goal is that the motion path of the white dot will follow the area you want to blur for the clip's entire duration.
5. Apply the Track Matte Effect to the clip on Video 2
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The Track Matte effect is located on the Effects and Transitions panel, in the Video FX collection, in the Keying category. Drag this effect onto the Mosaic-modified clip on Video 2.
6. Define the dot as your matte
Now that we’ve created the path for our blur, using the dot, all we need to do is tell the Track Matte to cut a matte based on the position of the dot. In other words, since the Track Matte is applied to the clip on Video 2, once we connect the Track Matte to the dot, the area that the dot now covers will be all that will be displayed of Video 2 (the blurred clip). The area around it will become transparent, revealing the clean clip on Video 1. Make sense?
With the clip on Video 2 selected, click the triangle to the left of the Track Matte listing in the Properties panel to reveal the effect's control panel. From the Matte drop-down menu, select Video 3.
In version 1 of Premiere Elements, additional steps were required to render the white dot invisible. Version 2 nicely integrates a feature that simultaneously uses the dot to define the matte and hides the dot from the actual sequence.
February 2006
About Steve
Steve Grisetti earned a master's degree in writing for television and film from Ohio University. He has instructed college-level courses in television and video production, and has taught adult education classes on Photoshop and principles of design.
Steve spent nearly 10 years in the Los Angeles-based entertainment industry, working on the sets and in the production offices of several large television and film companies. Currently, he is employed as a graphic designer in the Marketing & Communications Department of a Milwaukee-based investment firm.
He also serves as host on Adobe's official Premiere Elements Support Forum and is author, with Chuck Engels, of "Adobe Premiere Elements 2.0 In a Snap," from Sams Publishing, Pearson Education.
