92. Blur an Isolated Spot on a Video Clip a la Cops
BEFORE YOU BEGIN
33 Add or Move a Clip on the Timeline
61 Add and Customize an Effect
74 About Advanced Effects
71 Make a Variable-Speed Pan and Zoom
94 Frame Your Video with an Image
104 Output to an AVI Movie
92. Blur an Isolated Spot on a Video Clip a la Cops
There's someone in your video who doesn't want to be there, or there's a logo or text in the background that you don't want to show. Or, heaven forbid, you've accidentally taped nudity!
Here's how to blur out the unwanted area in your video and then, using keyframing, track with its movement across the screen.
Place a Duplicate of Your Clip on Video 2
Because Premiere Elements can paste a clip only to the Video 1 track, drag the original clip to Video 2, and 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.
Ensure that both clips are perfectly aligned on the Timeline.
Place a White Dot Graphic on Video 3
You'll need a graphic of a white circle (or whatever shape best fits the area you want to blur) 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.
Graphic shapes without background layers travel only with Photoshop (PSD), TIF, and PDF files, so you'll have to save the graphic to one of those formats with the layers intact in order to maintain the graphic's transparency. (See 22 Prepare a Still for Video and 94 Frame Your Video with an Image.)
Use the Add Media button (described in 13 About the Media Panel) 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. Adjust its duration to match that of the other two clips, if necessary.
Create an Opening Keyframe for the White Dot
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 at the top of the panel. Click the triangle to the left of the Motion listing to reveal the control panel for this property.
Position the Properties panel's CTI at the beginning of your clip. Click the white dot in the Monitor and drag it so it covers the area you want to blur. Use the Scale and Position settings in the Motion control panel on the Properties panel to cover the spot you want to blur. (See 23 Scale And Position A Still.)
When the dot is in position and scaled, click the stopwatch icon to the right of the Motion listing in the Properties panel. A column of little keyframe diamonds appears on the Properties timeline at the position of the CTI. These are the opening keyframes for your motion path.
Set Subsequent Keyframes for the Dot
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 are 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.
Apply the Mosaic Effect to the Clip on Video 2
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.
Click the triangle to the left of the effect listing in the Properties panel to reveal the control panel, and adjust the settings until your screen image is distorted beyond recognition.
Apply the Track Matte Effect to the Clip on Video 2
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.
Set Video 3 as the Matte
A matte is an area of a clip you designate to be transparent. In this case, you are using the white dot to define the area you want to be transparent (the dot is the matte). True to its name, the Track Matte effect tracks this white dot around the video frame, applying transparency wherever the white dot appears.
KEY TERM Matte An area of a clip designated as transparent. The shape and position of a matte can be defined using vector points (as with Premiere Elements's Garbage Matte) or by linking it to the size and position of an image on another video track (as with Premiere Elements's Track Matte).
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.
The Track Matte creates a mask for the clip on Video 2 around the white dot. In other words, only the spot where the white dot is positioned will show the Mosaic-effected clipthe rest of the video frame displays the clear clip on Video 1. As the dot moves along the motion path you've created for it, only that area appears with the Mosaic effect.
Note that, in Premiere Elements version 1.0, the Track Matte effect does not follow a keyframed graphic. To make this effect work in version 1.0, you must export the keyframed clip of the white circle as a movie (see 104 Output to an AVI Movie) and then use that new clip as your matte.
As an alternative to using the Track Matte effect, you can duplicate your clip as explained in step 1, blur the clip on Video 2 as explained in step 5 but, rather than using the Track Matte effect with a keyframed graphic, apply the 4-Point Garbage Matte effect (from the Keying category in the Video FX collection) to the clip on Video 2. Positioning the four vector points for the Garbage Matte, you can isolate which area of the clip appears blurred. The positions for these vector points can, likewise, be keyframed for motion.