Luma/Chroma Keying a Lightsaber Effect

[SpectacularKevin]

Hello,

I recently grabbed a pretty high quality lightsaber prop. The light is very bright and can also change colors.

I have been messing around with using a luma key to key out the brightness of the saber. I turn that into a matte and use the matte on a copy of the base footage. I then take that copy of the base footage layer (with the lighstaber matte applied to it) and use the levels tool to brighten the saber even further so that it is the brightest part of my scene. 

I then put an adjustment layer above the whole comp and use Red Giant's Optical Glow plugin on that layer. I turn up the "highlights only" to around 95% so that only the blade glows. This makes a very fast and easy lightsaber effect as long as the saber is the brightest part of my footage to begin with.

The green saber color is very green as well so I can also key it out using primmatte keyer or similar chroma keying effects; however, I would love to have proper exposure on these lightsabers like in the Sequel Trilogy. Lightsabers are no longer extremely bright lights with colored falloff, they now feel more properly composited into the scene with even the white parts being slightly more tinted to their color. I want to match this look while somehow keeping the quickness and ease of the method above.

Does anyone know of a way to apply glow or a similar effect to just one color channel? For example, can I key out the green and then make only the green channel glow while keeping the proper exposure because sometimes the blade does not have the bright white core in the center. Sometimes it is a subtle white, with more of the green showing through. 

Any additional ideas are also welcome but I want to avoid having to animate a digital blade over my footage.

[Mylenium · Accepted solution]

You isolate channels using channel effects like Shift Channels/ Set Channels and Channel Combiner and that's also the way to re-combine them short of using blending modes like Add. That's pretty much all there is to it. The only real issue is that you easily end up with tons of layers since due to how AE works you need one layer for each channel. and that's probably where the wheels will come off your quick & dirty method - it's not going to work this way and you have to put in much more effort by creating all the necessary pre-compositions.

Mylenium