Quba Michalski offers a great little tutorial showing how you can use subtractive color in After Effects for color correction.
automatic splitting of the image/footage into discrete RGB or CMY channels
The Subtractive Color model can be much more intuitive when making color decisions as it is the very first thing we learn about color. Who among us has never switched to CMYK from RGB temporarily in Illustrator just to layout colors in an image?
This is why Quba has created the QHQ Channel Splitter, which is both a script for After Effects and and Action for Photoshop that will automatically split the image or footage into discrete RGB or CMY Channels.
Using subtractive color in After Effects can open up a brand new way of color correcting or grading which can be much more intuitive than channel values. Check out the tutorial and the free preset for QHQ Channel Splitter here.