Keying Uneven Blue Screens

If the blue screen you are keying is grainy, you should apply a key-in blur to smooth out the blue before keying.

If a key-in blur is not enough to correct the blue screen, use other filters to adjust the blue screen, and use the corrected blue screen as a key-in source.

To use the corrected blue screen as a key-in source:

1. Import the blue screen footage and the background into one composite branch.



2. Create a second composite branch. To do so, choose File | New, and select Composite from the Type list.
3. To add an instance of the blue screen footage to the new branch, choose Object | New Layer from Operator, and choose the blue screen footage from the Operator Picker dialog.



4. Select the new layer, and apply filters to correct irregularities in the blue screen.



5. Double-click the composite that contains the image to be keyed, select the Front layer, and apply a Discreet Keyer operator.



6. In the Keyer controls, click Setup.
7. In the Setup controls, click the Key In Source button, and choose the corrected blue screen from the Operator Picker dialog.



8. Pull a key as described in this chapter. The resulting matte is created based on the key-in layer but it is applied to the front layer.