Grass Valley DD35 Family v.3.1.5 - Manual (Page 215)

3. Menu Operation DD35 Production Switcher
3 – 63 Operating Instructions – Rev. 16 / 10.2001
3.7.5 CHROMA KEY MENU
In DynaChrome
t
mode, the foreground signal is proportionally and subtractively
deprived by the key color in the key color area and colored neighboring areas. The
result is a cleaned key fill signal which now contains in key color areas shadow-free
black and in the transition regions the de-mixed foreground colors.
The key control signal is also derived from the foreground signal. The key control
signal is multiplied with the background signal. The cleaned key fill signal and the
multiplied background signal are added. This method ensures that all details are
reproduced true to the original in the area of the key color.