Knoll Unmult ~upd~

: It calculates transparency based on the brightness of the pixels. Pure black becomes 100% transparent, while lighter colors remain opaque or semi-transparent.

Many 3D programs (like Cinema 4D with standard renderers) output specular, reflection, or shadow passes on black. Unmult isolates the bright information, allowing you to "Add" the specular highlights back into your main comp without black fill.

It is called .