From the course: After Effects Compositing: 4 Color Keying
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Create a luma key with Extract - After Effects Tutorial
From the course: After Effects Compositing: 4 Color Keying
Create a luma key with Extract
- In this lesson we'll look at how to create a matte using only luminance. This is know as a luma key. The result is what's called a high contrast or hi-con matte, which while generally cruder than a green screen or blue screen color key can certainly be an effective way to separate foreground and background when you need to and when you can get away with it. Here is a scene which among other things is just begging for a sky replacement because this was an overcast day in Portland and there's nothing going on up there. So to start I'll apply the extract effect. It's among the keying effects there used to be a luma key effect in after effects happily it was obsoleted because it was pretty bad. I thought that by moving my cursor around I'd see the histogram and now I do. I can extract the luminance channel but I also have the option to choose one of the individual color channels. I usually like to look at the three color channels and decide which one has the best contrast. So between…
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Contents
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High-contrast mattes: Introduction57s
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Create a luma key with Extract3m 27s
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Set up a simple sky replacement in 32 bits per channel2m 38s
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Improve detailed edges with Refine Soft Matte3m 29s
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Feather edges with Channel Blur3m 26s
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Conceal matte lines with an edge matte4m 37s
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Expand and contract a luma matte with Minimax2m 9s
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