User Manual

written simultaneously to all three RGB channels. However, you could also render
separate pure primary-colored mattes to each color channel (a so-called “disco” matte),
so that the Red channel has one matte, the Green channel another, and the Blue
channels still another, thereby exporting three separate mattes within a single media
file, for convenience. If you add another matte to the Alpha channel, you can even
export four mattes within a single file. You can then use each one of these mattes
individually by connecting the correct output of the EXTMATTEnode. (Note: For
backward compatibility, projects from versions of DaVinci Resolve previous to 12.5
continue to output RGBY from the square outputs, not YRGB.)
 RGB Output: A square green RGB output lets you connect the RGB image data of a
matte clip to any other clip’s RGB input. This is especially useful when you’re combining
a matte clip with the current clip using a Layer Mixer node, to create a textured
composite of some kind.
External Mattes to Limit Adjustments
Going back to the External Matte node’s original use, mattes are typically grayscale media files
that represent image opacity, and are meant to be used either as alpha channels for creating
opacity within a corresponding RGB clip, or as a matte for limiting effects.
An example of a matte channel would be the key created by a green screen keyer. If you output
just the key, that would be an external matte. If you receive an external matte along with an
effects clip, you can attach the matte to its corresponding RGB clip in the Media page. Then,
you can access that matte via an External Matte node in the Node Editor, so you can use the
key it outputs to limit different kinds of corrections you want to apply.
In the following example, the keyed matte of a green screen composite clip is used to apply
different corrections to the inside and outside of a keyed composite, in order to make the
subject match the background more convincingly.
A matte attached to clip Makeup_Green.mov, as seen in the Media Pool
To use a clip matte to limit an adjustment within a Clip grade:
1 Right-click any node, and choose the attached matte you want to use from the Add
Matte submenu of the contextual menu.
By default, the EXT MATTE node that appears has its first output connected to the
Connect one of the EXT MATTE node’s triangular key outputs to the key input of a
node you want it to limit.
2 Select the node to which the EXT MATTE node is attached, and add an Outside node
to make it possible to add adjustments on either side of the matte.
Chapter – 126 Combining Keys and Using Mattes 2860