Increase brightness on video out

To increase the brightness for video display on games what are the options? Is there more than one way to do so on cores or retroarch settings? I know not all games have a brightness adjustment setting.

Part of the reason is I want to create screenshots with higher brightness levels of the game.

You can use the image adjustment shader, but it’s purely post-processing. I can’t create detail that isn’t included in the output image (i.e., if a game has its own internal black-crush happening, the shader can’t fix it).