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Best way to pull key then render B&W png seq with alpha?

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Todd Groves

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Best way to pull key then render B&W png seq with alpha?

PostTue Jul 10, 2018 1:34 pm

I need to pull keys from green screen shots, then render out black and white PNG sequences with alpha.

I'm coming over from Nuke and I'm still learning how to translate techniques from Nuke in Fusion.

Is there a good workflow for doing this?

Thanks in advance.
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michael vorberg

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Re: Best way to pull key then render B&W png seq with alpha?

PostTue Jul 10, 2018 1:41 pm

The same as in nuke: pull the key and then copy the alpha channel to rgb (in fusion you can use the channel boolean node, it's close to the shuffle in nuke),
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Todd Groves

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Re: Best way to pull key then render B&W png seq with alpha?

PostTue Jul 10, 2018 2:02 pm

Thanks for the quick response. What settings do I use in the Channel Boolean to isolate the alpha? I haven't used the Channel Boolean, yet.
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Bryan Ray

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Re: Best way to pull key then render B&W png seq with alpha?

PostTue Jul 10, 2018 2:09 pm

There's actually a checkbox in the Export tab of the Saver: 'Save Alpha to Color.'


edit: But since you really need to understand Channel Booleans, you have first the Operation, which in its default Copy mode will do what you want. The channel list tells you exactly what is going to happen:
Copy To Red: <channel>. So to put the Alpha in the red channel, you'd just set the 'To Red' control to Alpha BG. Thus, Copy To Red: Alpha Background.

Suppose you have two alphas that you want to intersect—a classic Boolean AND. Set the Operation mode to And (or Multiply—mathematically they're identical), and set To Alpha: Alpha FG. The result is Alpha BG * Alpha FG.
Bryan Ray
http://www.bryanray.name
http://www.musevfx.com
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Todd Groves

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Re: Best way to pull key then render B&W png seq with alpha?

PostTue Jul 10, 2018 2:23 pm

Thanks, Bryan. Thanks everyone.

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