Settings > Cameras > [Camera name] tab.
The default option for your camera is that the video image options are set to ”Auto Levels,” meaning that the brightness and contrast levels are maintained automatically by the camera. (Notice, for example, that the “Auto Levels” checkbox is checked).
However, you can turn off the “Auto Levels” and control the Brightness and Contrast levels yourself for the camera.
Brightness Slider
Slide the bubble toward + to brighten and toward the – to darken the image.
Contrast Slider
Slide the bubble toward the + or – to adjust image contrast.