[Already In] Please add overall brightness.

[wanisea]

Gamma is not good to see because the screen is too heterogeneous.
Hopefully there's an option to increase the overall brightness like the Bethesda Classic Doom.
sorry for inconveniencing to you.

[Caligari87]

I do not know if the developers are interested in adding this, but some suggestions that may help:

• GZDoom includes Brightness, Contrast, and Saturation post-processing controls, in addition to Gamma.
  
• Changing your sector light mode to something like "Bright" can help.
  
• Make sure your monitor is calibrated properly. Many monitors are too dark by default.
  
• Turn off "Fog" in GZDoom settings, will make things more visible at a distance even in many dark rooms.
  
• You can use DarkDoomZ to adjust in-game sector brightness (Advanced Settings > adjust "PreGain" or "PostGain" upwards).

[Dewzanity]

Or another suggestion, if the level is dark you can use the console command "r_visibility", and the higher you set the value, the stronger the light that will illuminate from the player. Default is set to 8, this is useful if you want to see better in dark levels, or in regular levels it looks like everything is fully bright with a high value.

This only works when sector light setting is set to "software".

[wanisea]

Or another suggestion, if the level is dark you can use the console command "r_visibility", and the higher you set the value, the stronger the light that will illuminate from the player. Default is set to 8, this is useful if you want to see better in dark levels, or in regular levels it looks like everything is fully bright with a high value.

This only works when sector light setting is set to "software".

It helped a lot.
There is another way to increase the overall brightness using Shader Tools. I also want to say thank you to Pixel Eater.
viewtopic.php?f=103&t=59289