I was needing a feather on an animated garbage matte and this got me going in the right direction. Here's a slight modification that might make keyframmed garbage mattes easier. Instead of using the titler, just add a black video or color matte clip in place of the title for your matte track.
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The actual color doesn't matter. Next add your garbage matte to the matte track instead of your video clip. Keyframe as needed now or after matte keying. Follow Jon's other steps to add the Drop Shadow to the matte track and apply Track Matte Key to the video track below and you're good to go. Thanks for the great tip Jon! Color correction is essential to making every video look its best, and Adobe Premiere Pro has a lot of great tools built in that are both powerful and easy to use. Most important, they can help bridge the gap between color displayed on the monitor you're using, and the devices your viewers will be using.
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Video editing and VFX whiz Tobias Gleissenberger of Surfaced Studios will walk you through the waveform monitor, the RGB parade, and vectorscopes built into Premiere Pro, as well as helping you understand how they work together.