Barco 7QP, User Manual

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7. Advanced
7.3.5 Input balance (RGB signals only)
Introduction: Unbalanced color signals
When transporting signals, there always is a risk of deterioration of the information contained in the signals.
The alterations of the three color signals will happen independently i.e. the colors will end to be unbalanced.
B
Black level
0.7V
Image 7-13
Black level
Δ G
ΔΒ
Δ R
R
G
B
Image 7-14
The objective of input balancing
The objective in input balancing is to “set” the same black level and the same white level for the three colors of a particular input
source.
Black level setting : brightness
White level setting : contrast
The same absolute black and white level for the three colors allows the same reference for brightness and contrast control of the
picture!
These two references also set the range in which the ADC will work for that particular source (this also explains why each input
balance setting is linked to a particular source and thus saved in the image
fi le).
How can it be done ?
To balance the three color signals of a particular source there are conditions; in fact we must know the black and the white level of
the source i.e. :
1.
the considered source must be able to generate a white signal, ideally a 100% white (background) full screen pattern
2. the considered source must be able to generate a black signal, ideally a 100 % black (background) full screen pattern
A
B
Image 7-15
White balance : In the projector, we will set the contrast for each color until we get a 100% light output picture when projecting a
100% white image (image A)
Black balance : In the projector, we will set the brightness for each color until we get a 0% light output picture when projecting a
100% black image (image B).
88 R59770330 SIM 7QP SERIES 07/10/2013