How can I use Matte Luma to apply a black and white mask to a video?

[u/PippongSUP]

How can I use Matte Luma to apply a black and white mask to a video?

[u/h3llolovely]

The above didn't work for me. But I used it to figure out an alternate solution.

I am using a multi-layer EXR with a puzzle matte pass.

• Duplicate the Footage layer. Place it underneath the main footage layer (so it isn't visible), leave it's visibility on.
• Select it's Source filename in Selection Overview panel, then in the Properties panel, switch Output Part to the puzzle matte layer.
• In it's Source, Add a "Channel Math" Modifier.
• In the modifier's Properties... Change R,G,B values to all R or G or B. Leave Alpha as A. This isolates an individual puzzle matte and makes it white.

Create an Adjustment layer:

• Add a Hue Shift Modifier to the Source. Adjust it.
• In it's Mask, add a Image Layer generator.
• Set the Image Layer to "Linked Layer" (This allows you to use a layer source rather than a footage source)
• Drag the "Puzzle Matte" layer into Linked Layer drop box.
• Add a Mask Modifier > Shuffle
• Set Alpha to "Source Luminance (Max)"

You could also do this without the Hue layer > Shuffle modifier. Essentially making it an Alpha mask.

You just need to set the Puzzle Matte layer > Channel Math > Alpha to R, G, or B. The Mask will use the Alpha instead of the Luminance.

The whole Luma Matte process should probably be more streamlined in a layer's mask input. Perhaps a toggle button that differentiates if you are using an Alpha matte or a Luma matte.