You can play around in the Color management tab, the look exposure or gamma. Bare in mind that it will change the whole look in Blender.
1 love
Martin Bergwerf
replied
And there is also a Color > Brightness/Contrast Node....
2 loves
Kent Trammell
replied
I wouldn't say the vignette overlay affects contrast so much as it darkens the borders of the frame and lightens the center. It's not making existing dark values darker and light values lighter...
Can you elaborate on what you mean by reducing contrast? Perhaps a screen shot of your render with annotations?
