8. Configurator, Projector adjustment settings
One can conclude here thata good color trackingc an only be met by using three previ-
ously (input) balanced color signals
Analog Digital Conversion
The analog color signals must pass through an Analog/Digital conversion circuit prior to any digital pro-
cessing in the PMP.
A typical ADC transforms the analog value into an 8 bit coded digital signal.
The graphic shows that when converting a signal containing a DC offset component the range of the
converter is not optimally used.
Black level
Δ
R
ADC
0
255
i1 : superfluous information
i2 : video information
Image 8-24
One can conclude here that a good data conversion can only be met by using three
previously (input) balanced color signals
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 Brigh tness
and Contrast control of the picture !
Thesetwo references also set the range in whichthe ADC willwork for that particularsourc e (this explains
also why each input balance setting is linked to a particular source and thus saved in the image file).
8.5.9.2 Adjusting the input balanceHow can it be done ?
Tobalanc e 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 source in question must be able to generate a white signal, ideal ly a 100% white (background)
full screen pattern
2. The source in question must be able to generate a black signal, ideal ly a 100% black (background)
full screen pattern
130 R5976924 PROJECTORTOOLSE T 16/04/2009