Use the settings in the Blending tab to adjust blending curve for each surface.
(a) Front matte curve  (b) Back matte curve  (c) Matte box  (d) Blend Curves option box (e) Keyframe option box (f) Reset Selection box
Matte boxSelect the matte curve you want to adjust.
Keyframe Option boxSelect an option to Set, Delete, or Reset keyframes. If Auto Key is enabled, a keyframe is added automatically when you adjust the blending curve.
Home buttonResets the curve view.
Reset Selection boxSelect whether to reset the selected curve or all curves to their default settings.
Blend Curves option boxSelect whether to work with the surface blend curves or view the exisiting keyer blend curves.
For more information on using the blending curves, see Applying Blending Curves per Surface.
