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Participant
May 29, 2020
Question

Render with alpha channel for colour correction

  • May 29, 2020
  • 2 replies
  • 1125 views

Hi there!

I am working on a film where I have keyed out the green screen window background an repleced it with a movie clip. Now the colorist wants me to render it in alpha channels so that he can correct the background and the foreground in different layers. How do I do that without rendering it twice - once with the foreground film with alpha channel so that it becomes transparent and once with the background film only, so that he can put them together?

 

I have already an alpha channel in the comp for keeping the reflexions in the window. C0013.MP4 is the background footage. Hope you understand, though my explanation (and English) is poor.

 

All the best,

Åsa

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2 replies

Legend
May 29, 2020

The correct way to pipeline through a third-party colorist is to export a wide gamut master, usually an EXR frame sequence. EXRs can include unpremultiplied alpha channels and multiple layers.

Participant
May 29, 2020

Hi Dave!

Thank you!

Is this something I do when rendering, the wide gamut master? Or do I have to prepare the comp in any way?

 

Martin_Ritter
Legend
May 29, 2020

You can give the background film to the colorist, if you didn't do any alternations on it and only have to render the forground film with alpha.

 

Otherwise, you need to render twice in order to get two video files with different content.

You can (temporary) duplicate the main comp, and switch off the layers accordingly (comp1: only foreground visible, comp2: only background visible) - then you can add both comps to the render queue and render them in one sitting.

 

*Martin

Participant
May 29, 2020

Hi Martin!

This is what I did - rendered in them twice and got two comps to the colorist. I was wondering if it is possible to get only one file which he can work with? Thank you for your respons!