Inverted S curves (Colors > Curves...), 
 
   
then duplicate the layer, then high pass in overlay mode (Filters > Enhance > High Pass...) on the duplicated top layer, and duplicate that high pass layer as your liking/necessary to "dramatize" (duplicated will stay in overlay mode).
There is more than two grooves... Time to change it 
 
 
   
	
	
	
then duplicate the layer, then high pass in overlay mode (Filters > Enhance > High Pass...) on the duplicated top layer, and duplicate that high pass layer as your liking/necessary to "dramatize" (duplicated will stay in overlay mode).
There is more than two grooves... Time to change it
 
 
Patrice
	

 

 
