As you work with different nodes to create your key, it is often useful to see the effect of your changes on the image at a later part of the pipeline. You do this using context points. You set a context point on a particular node, then view that context point from the node you are working in. For example, you could place a Degrain node at the beginning of the Matte branch and set a context point on the Keyer-3D node. You could then degrain the clip while viewing the context point, in this case, the Current Result of the 3D Keyer.

You can set two context points in the pipeline.

To set context points:

1. Press and hold = and click the node, or select the node and click Set Context.

   
   

   A green dotted border appears around the node and (C1) appears below the label.

   
   

   (a) Context Point 1 set on GMask node  

   Images courtesy of Behavior Communications Inc.

2. To set the second context point, repeat step 1 on another node. The second context point has the same green border and (C2) appears below the label.

   When you next set a context point, the context point that was first set disappears. The (C2) context point is changed to (C1) and the new one becomes (C2). The oldest set context point is always Context Point 1, and the newest one is always Context Point 2. The oldest context point is always the one to get removed when you add a new one.

To view a context point:

1. Set a context point.
2. Select the node you want to work with.
3. Select Context1 or Context2 from the View box, according to the context point you want to see. Alternatively, press 1 for Context Point 1 or 2 for Context Point 2.

   
   

   As you make changes, you see the effect the changes are having on the selected context point.