XMult is a freeware plug in for Adobe After Effects.
XMult creates an alpha channel based on the highest luminance value for each pixel.
A compensation is made to the RGB channels due to the attenuation of the applied alpha channel.
This is very useful for extracting a forground object filmed against a black background, e.g. explosions or fireworks.
XMult supports 8, 16 & 32bpc
Adobe After Effects CS5 or later
MacOSX 10.6 or later, Intel x64
Windows 7, Windows 8 & Windows 10