2017

NOTE The Degrain node results in a colour image; however, it is often useful to place it on the Matte pipe before
the MasterK node (which uses a colour image for its input). For this reason, it can be placed on the Matte pipe.
The Front and Matte pipes of the MBlend node constitute one layer.
(a) One layer (b) Front pipe (c) Matte pipe (d) Blue box of Front pipe (e) Blue box of Matte pipe
The two pipes together, along with a back component, constitute one layer. For the first (bottom) layer, the
MBlend node uses a pure black image for the back component.
Working with Blend Nodes
The two pipes of blend nodes provide extra functionality compared to branches in the pipeline:
■ You can apply the processes to a selected region of the image. You use the lower of the two pipes to
define the area on the image where you want to apply the processes used in the upper pipe. For example,
you could add a garbage mask node to the lower branch and create a matte. The processes in the upper
pipe are only applied to the foreground subject of the matte. If there are no nodes in the lower pipe, the
processes in the upper pipe are applied to the entire image.
■ You can blend the two pipes in various ways. Use the menu settings and Blend Curve editor to adjust
the blending of the front and back images.
■ You can use multiple layers. The two pipes together constitute a layer. You can add one to three additional
layers to blend nodes.
Adding a Matte to a Blend Node
Add a matte to the Matte pipe of the CBlend and MBlend nodes to limit the area on the image where the
colour correction or matte will be applied.
You can use any matte operation in the Matte pipe—add any combination of nodes that you would want
to use to isolate an area of the front image. For example, you could add a garbage mask node to the Matte
pipe of the CBlend node.
To add a matte to a blend node:
1 Drag the node to the Matte pipe. Release the cursor.
The node is added to the Matte pipe.
682 | Chapter 16 Chroma Keying and Working with Green Screens