I hope you are doing fine, I am testing Some Color Channels adjustment techniques for example like the following Video
So which Tools we can use to do same job?
FAQ Composer Node System
For basic calculations (multiplication, addition etc.) you can use the Blender node.
Other useful nodes:
Clamper (limits the minimum and maximum values)
Adjuster (adjusts contrast and brightness)
Levels (stretches out values in the selected interval)
All the calculations listed work on RGB pictures or on individual channels (monochrome picture) as well.