So basically what I am trying to do is when the screen renders an object that is red or blue, it becomes green during the rendering process without changing anything about the object or material. As in a pixel with a value of FF0000 becomes 00FF00, but not exactly that. I was thinking more like a system to divide the red, green, and blue of a given pixel by 3, then add them together into the green slot, for the entire screen I might add. Or perhaps finding which color value is highest and making the green that value while turning all other values to 0. I know that there are post effects like the VHS scanlines, so surely something similar to this must be possible.
BTW I already figured out how to do that I just cannibalized the sepia posteffect.