In my last post, I talked about masks in After Effects, specifically the new motion tracking feature for rigid masks. In this post, I’m again focusing on video composition, but instead of compositing using masks, I’m going to talk about keying.
Keying is a technique for selectively removing areas of a video based on content inside of that video, so that there is transparency. With this transparency, you can add layers and special effects to your video compositions. There is color keying, which removes pixels with specific colors from a video, luminance keying (luma key), which removes pixels based on brightness value, track matte key, and more… all of which are just different methods of removing pixels from a video and adding transparency.
If you’ve ever wondered how news programs get the weather person to appear in front of an animated weather map, they’re just using color keying/green screen techniques. This is when the subject (the weather person) is captured on a green background, and the green background is removed using color keying. Then you’re just left with the weather person, which can easily be composited/overlaid on top of the weather map.
Check out the video below to see two examples of keying in action (scroll down to jump directly to the video)… The first example shows how to use a green screen/color key technique in Adobe Premiere to overlay a subject on a background video.
Attribution: Dog Video, Beach Video – You’ll get better results with higher quality video – I just used these for simplicity. The dog video is licensed under Creative Commons with attribution, and the beach video is a preview file from Pond5.
The second example shows usage of color keying to overlay an explosion over a more complicated scene in After Effects – complete with motion tracking, and additional masking to make the explosion look like smoke is billowing down the streets between the buildings.
Now, check out the full video to see how to apply these techniques. You already have have everything you need for these within Creative Cloud.
Here are the techniques that I used in these samples:
- Color Keying in Premiere Pro (I used the Ultra Key)
- Track Motion in After Effects
- Masks in After Effects
- Linear Color Key in After Effects
- Tritone Color Correction in After Effects
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