Turn to gradient or something

[InterGraphenic]

There used to be a tool under adjustments where you could select a channel (R,G,B,H,S,V,C,M,Y, or K) and map that to a gradient between colour points you can choose. I distinctly remember using it to separate the 3 RGB channels to apply distortion effects. Is this a thing or am I losing my mind?

[Rick Brewster]

... Curves? If not then it was a plugin

 

[AndrewDavid]

Hello @InterGraphenic 

You will not only find it here, but also an answer that may rectify your problem

 

I remember the issue well. Hope this helps.

 

[InterGraphenic]

thank you