From the course: Learning After Effects

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Extract a moving holdout matte from the sky

Extract a moving holdout matte from the sky - After Effects Tutorial

From the course: Learning After Effects

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Extract a moving holdout matte from the sky

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If you've ever watched any movie behind-the-scenes clips you know that it's common in visual effects shots to remove a blue or green screen to replace a background. Extracting the sky so the moon can rise behind the hills will be simpler than that. After Effects does have some amazing keying controls so to get started I'll duplicate the background layer and I'll just call this Hills and move it right up to the top. So now it's covering the moon completely. I'll right-click on it and under Effect I'll choose Keying. There are a number of tools here including Keylight which has actually won an Academy Award but in this case Extract which is the word I was using in the intro and in the title of this lesson is the one we want. So here we see a histogram. You may be familiar with these. It's showing from dark to light what pixels are in the scene. Now I have a suspicion that because the sky is blue, if I look at the blue channel instead of luminance, I'm gonna see better contrast. And sure…

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