Out of inDesign, the printed material looks too dark. I get the dot gain thing, but I need to know how much to increase brightness of an image so they look proper.

I am adjusting the same image multiple times and sending that image to the printer to see how each one looks. The adjustment I’m making is Shadows/Highlights as I don’t exactly want to adjust brightness. I want the highlights to stay where they are. Curves also didn’t quite work as I intended.

“Amount” is the only parameter I’ll be adjusting: 5,10,15,20,25,30% and print them to see what the effect is in print.