9. Image
Black level
Δ
G
ΔΒ
Δ
R
R
G
B
Image 9-30
One can conclude here that a good color tracking can only be met by using three previously (input) balanced
color signals
Analog Digital Conversion
The analog color signals must pass through an Analog/Digital conversion circuit prior to any digital processing 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 9-31
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 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 explains also why each input
balance setting is linked to a particular source and thus saved in the image
fi
le).
9.3.7.2
Adjusting the input balance
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 source in question must be able to generate a white signal, ideally a 100% white (background) full screen pattern
2.
The source in question must be able to generate a black signal, ideally a 100% black (background) full screen pattern
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R5905032 HDX SERIES 20/11/2014
Summary of Contents for HDX series
Page 10: ...Table of contents 6 R5905032 HDX SERIES 20 11 2014...
Page 16: ...1 Safety 12 R5905032 HDX SERIES 20 11 2014...
Page 26: ...2 General 22 R5905032 HDX SERIES 20 11 2014...
Page 50: ...3 Physical installation 46 R5905032 HDX SERIES 20 11 2014...
Page 58: ...4 Input Communication 54 R5905032 HDX SERIES 20 11 2014...
Page 108: ...8 Input 104 R5905032 HDX SERIES 20 11 2014...
Page 138: ...9 Image 134 R5905032 HDX SERIES 20 11 2014...
Page 156: ...10 Layout 152 R5905032 HDX SERIES 20 11 2014...
Page 168: ...11 Lamp 164 R5905032 HDX SERIES 20 11 2014...
Page 294: ...14 Service 290 R5905032 HDX SERIES 20 11 2014...
Page 296: ...15 Maintenance 292 R5905032 HDX SERIES 20 11 2014...
Page 308: ...16 Servicing 304 R5905032 HDX SERIES 20 11 2014...
Page 310: ...A Dimensions 306 R5905032 HDX SERIES 20 11 2014...
Page 316: ...B Specifications 312 R5905032 HDX SERIES 20 11 2014...
Page 320: ...C Standard source files 316 R5905032 HDX SERIES 20 11 2014...
Page 324: ...D DMX chart 320 R5905032 HDX SERIES 20 11 2014...
Page 334: ...F Environmental information 330 R5905032 HDX SERIES 20 11 2014...