Review the questions and answers in this section to try to sharpen your Premiere transparency techniques. Also, take a few moments to tackle my short quiz and the exercises.
No matter how many different key types I try, I get a "halo" effect along the edges of my keyed objects, especially in their hair. What should I do?
This is endemic to this technology. Using DV camcorders and Premiere's less-than-pixel-specific keying controls means you may never get rid of those halos. Some video capture cards, such as the Canopus Storm, have a much higher quality Chroma key tool. You may notice that your local weather forecaster does not have such halos (unless you live in a tiny TV market that's behind the technology curve). Many of those stations use a keying technology from Ultimatte (www.ultimatte.com). It offers incredible flexibility and creates very clean keying in difficult situations, such as through smoke, hair, water, and glass. Ultimatte offers a Premiere plug-in for $1,495. The hardware prices start in the neighborhood of $28,000.
Why can't I see the video clip on the highest track? Isn't that how it's supposed to work?
If you make any kind of transparency adjustment to a track, Premiere turns off its display. Even if you use the little eye icons to turn off a video track, a clip with any transparency, even if it's only a 1% drop in opacity, becomes invisible. You can see the clip if you do a real-time preview or an Alt/Option-scrub preview, or if you render the clip.
How do you blend two full-screen clips?
Either of two ways: Use the opacity rubberband to reduce the opacity of the superimposed clip or use the Screen (or Multiply) transparency for a subtle blend that lets light (or dark) areas of the bottom track show through the superimposed clip. Screen more closely approximates the opacity rubberband effect. Multiply acts more like a real key.
What's the difference between the two sets of Chroma Key sliders?Similarity/Blend and Threshold/Cutoff? What's a more descriptive name for the Smoothing drop-down menu?
Similarity and Blend work together to set a "width" for the color range to key out of a superimposed clip and to blend the two clips smoothly together. Threshold and Cutoff deal with shadows. Threshold controls the amount of shadows from the superimposed clip that will display on the lower track's clip. Cutoff controls how dark or light those shadows are. "Smoothing" is the same as "anti-aliasing."
When do you use the Non-Red key?
Non-Red lets you key out, well, non-red backgrounds (that is, green and blue). It's a helpful backup if the Green Screen key doesn't work as well as you'd like, which may happen if the green is not true chroma green.
Use the Luminance key to isolate a ball by keying out a highly contrasting background. Then use motion settings to bounce it around a scene. Use acceleration and deceleration with the bounces and apexes to more realistically mimic a bouncing ball.
Create several titles. Place them in various superimposing tracks and fade them in and out of your Video 1 clip at various times, sometimes displaying more than one title at a time. Remember, you drag the edges of a title clip to make it any length you want. Finally, give a couple titles motion using the Motion Settings dialog box.
Experiment with the Chroma and Green/Blue Screen keys. Find a color and lighting that work well.
Ask to visit a local TV station or production studio to watch how they set up green/blue screens.
Start watching TV commercials more critically, looking for examples of compositing. It's a rare spot that doesn't use layering. This is a great source of ideas.