Matte Source
Matte color backgrounds (BG) are color signals that can be applied to backgrounds and keys. Color selection is done either by picking a preset color, or by adjusted hue, saturation, and luminance to create a custom color.
Select the matte generator (BG) on a background or key bus. The full region of the background or key is filled with the selected color.
Note: A color background can be a solid color, or a wash of two colors.