Adjusting red and blue colors in an emission / reflection nebula

In my recent image of the Cocoon Nebula, I needed to adjust the red and blue colors very selectively:

1. Keep the red in the core of the nebula (or maybe even increase it)
2. Reduce the red in the fainter dust lanes
3. Reduce the blue in the core of the nebula (to make it less pink and more red)
4. Increase the blue in the fainter dust lanes

I use the CurvesTransformation process for this:

First, I want to increase the red in the inner parts and decrease the red in the outer parts. For that, I click in the inner parts, the dust lanes around it and the dark sky parts and notice where these points are in the diagram in the CurvesTransformation process:

Level in core part of the nebula

Level in dust lanes

Level in dark parts of the sky

Now, I set three points at these different levels:

This now allows me to adjust the levels in these three regions independently with smooth transitions in between:

I the same for the blue channel:

Only here, I decrease the level in the core (to make the core look less pink and more red), increase slightly in the fainter outer regions and decrease in the sky areas.

Now, the sky has a greenish hue (due to reducing the red in there). I also decrease the green in this area (but leave it in the other areas):

This now neutralizes the background without changing the color of the nebula or the faint dust areas.

Compare before and after: