Tektronix Grass Valley 3000 - Manual (Page 259)

Using the Super Black Output
C-3
Drawbacks of using a Super Black Output:
■ The reconstruction of the video and key is rarely perfect, and
quite a bit of control adjustment is necessary to produce the
best results.
■ Keying from Super Black produces a hard-edged key only. No
shadows, softness, or transparency can be used.
Generating Super Black
The basic equations for a Super Black Signal are as follows:
Super Black Output = Input Key (Input Video - Super Black
Value) + Super Black Value.
When the Input Key Value is 0:
Super Black Output = Super Black Value.
When the Input Key Value is 1:
Super Black Output = Input Video.
When the key is in between 0 and 1, you get a linear mix
between the Super Black Value and Input Video.
NOTE: The following two methods of generating a Super Black output
are mutually exclusive. If you use the Super Black matte to generate your
Super Black output you should not turn on Super Black on the
corresponding output module, or vice-versa.