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channel question

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Donald Mitchell
channel question
on Mar 19, 2020 at 12:45:08 pm

Ho do I remove the blue channel only from an RGB clip as a black and white video, to use as a mask elsewhere?

So easy in Photoshop, but I can't figure it out in AE!


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Graham Quince
Re: channel question
on Mar 22, 2020 at 3:08:38 pm

I think - might be wrong but I think - what you want is Shift Channels. And set the Take Alpha From to Blue channel.

This will make the video use the blue as an Alpha channel. Set that layer above your other footage and set that layer's Track Matte to Alpha.

Are you trying to use one layer's blue background, to cut out from another? If so, then it would be better to use Keylight to chromakeying out the background, and use the Track Matte to Alpha to sort the cutout.

http://www.YouTube.com/ShiveringCactus - Free FX for amateur films
http://shiveringcactus.wordpress.com/ - FX blog


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