The Split color map node splits the red, green, and blue channels of an input color mask and outputs a mask from each of these channels. Each channel with values between 0 and 255 is normalized to be stored in a mask.
The inverse operation is provided by the Color map from masks node.
To add a Split color map node, right-click in the Graph Editor and select Create Node > Color > Split color map.
This node has no parameters.
Use the Fast-creation menu by clicking and dragging the input connector to find compatible color map nodes.
If the color map does not have any transparency, the alpha channel will be entirely white.