Some digitizers have a software-based exposure level that compensates for changes in light conditions. If your video digitizer and camera do not have a brightness control, you can use SiteCam's brightness control.
Many video cameras have auto-iris control.
If your camera compensates for brightness, leave the refresh rate and brightness level unchecked. Because if the light level changes, the next time the video digitizer takes a picture, the brightness level will be incorrect. This can affect the quality of saved images, as well as cause the first few streamed images to be either too bright or too dark. Setting the Preview Window Refresh Rate can be used to change how often the preview window redraws with a new image.