• Adobe After Effects

  Alpha Mattes vs Luminance Mattes?

  Posted by Michael McKnight on October 8, 2022 at 1:46 pm

  Hi guys!

  Which do you prefer using: alpha or luminance mattes?

  They both do the same job but, for example, if a make a rough roto mask in a program like runwayml and export it for refining in After Effects, which one is better?

  If I export an alpha matte I can use Refine Hard/Soft Matte and Matte Choker without precomposing, but they are bigger files.

  Black and white luminance mattes are way smaller, but I have to precompose before I use matte-refining effects, precomps are a pain in the butt that grows exponentialy with the complexity of the project, so I tend to avoid them whenever possible.

  I’m interested to hear which one you prefer?

  Walter Soyka replied 3 years, 10 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Walter Soyka

  October 11, 2022 at 7:55 pm

  You can use the Shift Channels effect to easily move luminance information into the alpha channel without precomposing. Apply Shift Channels, set “Take Alpha From” to “Luminance,” and set each of the RGB channels to “Full On.”

  Now you can apply matte-refining effects in that same stack, without the need to precompose.

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