Tektronix Grass Valley 3000 - Manual (Page 125)

3-17
Chroma Key
The chroma keyer includes background and foreground
suppression. Background suppression replaces the old
background color with black before adding in the new
background. This ensures that the old background color is
completely removed from the scene, resulting in a cleaner key.
Foreground suppression is essentially a second chroma keyer that
allows you to detect and remove the background color and its
variations that “splash” onto foreground objects, as sometimes
happens when the foreground object is placed near the
background. The detected foreground “splash” color is replaced
with a neutral color and luminance value that restores the natural
color of the foreground object.
Both background and foreground suppression include menu
controls for selecting the hue to be replaced and for adjusting the
luminance and chrominance levels in the areas of the picture
where suppression is applied.
NOTE: Refer to The descriptions and illustrations in Chroma Keying
Operations in Section 4 of this manual.