To adjust the brightness of mid-tones on your desktop without affecting shadows and highlights
From the NVIDIA Control Panel navigation tree pane, under Display, click Adjust Desktop Color Settings to open the page.
If applicable, select the display on which you want to change the brightness setting.
(Windows Vista and later) Click the Use NVIDIA Settings radio button.
Note: Applications and games can still apply their own built-in color settings. When this happens, the Other applications control color settings radio button becomes selected.
Move the Gamma slider to increase or decrease the Gamma on your desktop.