This method, in Photoshop, is called the J GaBany method.
 

It does what Saturation does, but without inducing noise or other artefacts.
 

Make three copies of the frame, these will lie above each other in the layers list.

With the top one active, make the blending mode Luminosity.

The second one, Soft Light.

Then make all three active and “merge layers” them together. 

It makes the nebulosity brighter, but gently, so you may feel the need to repeat it. It will bear multiple repeats.

Brian