Barco Hdx Series Installation Manual

							9. Image
9.3.7 Input Balance
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							9. Image
9.3.7.1 Introduction to Input Balance
Introduction: Unbalanced color signals
When transporting signals, there is always a risk of deterioration of the information contained in the signals.
In case of information contained in the amplitude of the signals which is the case of data color signals (R, G, B),image 9-28 , we are
quite sure that the amplitude of these color signals is subject to alterations.
An example of alteration may be a DC component added to the signal, in the form of a DC offset repositioning the black level, since
thisblack level(“brightness”) will become crucial later on (clamping circuit) it will result in “blacknot being black”.
Another value that is subject to alteration is the amplitude of the signal, resulting in an altered “Gain” of the signal (“white level”or
contrast).
The alterations of the three color signals will happen independently i.e. the colors will end to be unbalanced, image 9-29
B
Black level
0.7V
Image 9-28
Black level
ΔGΔΒ
ΔR
RG
B
Image 9-29
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 anAnalog/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 levelΔ
R
ADC
0 255i1 : superfluous information i2 : video information
Image 9-30
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.
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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 imagefile).
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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
AB
Image 9-31
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 foreach color until we get a 0% light output picture when projecting a
100% black image (image B).
The changeover from min to max is indicated by the apparition of bright spots also called “digital noise”
An alternative to a full screen White/black pattern is the standard gray scale pattern, the white bar will be used
for white balance and the black bar for black balance.
Image 9-32
How to adjust
1. PressMenuto activate the menus and selectImage→Image Settings→Input Balance.
Image 9-33
Main menu, Image
Image 9-34
Image adjustments
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							9. Image
Image 9-35
Image settings, input balance
Image 9-36
2. PressENTERto select.
3. Do you want to use an internally generated test pattern ?
If yes, use the▲or▼key to selectAdjustment Patternand pressENTERto toggle between [on] and [off]
If no, adjust on the selected source.
4. Use the▲or▼key to selectRedbelowBlack balanceand pressENTER.
5. Adjust the red black level on a minimal value
6. Use the▲or▼key to selectBlack balance blueand adjust the blue black level on a minimal value.
Note:This minimal value is not necessary , provided that the 2 other colors are not influencing too much the color to be adjusted,
in fact the aim is to minimize the effect of the two other colors since there is a risk of reaching too soon the 50% transition
due to the contribution of these two other colors signals.
7. Use the▲or▼key to selectBlack balance greenand adjust the Green black level until bright spots appear on the screen.
8. Use the▲or▼key to selectBlack balance blueand adjust the Blue black level until bright spots appear on the screen.
9. Use the▲or▼key to selectBlack balance redand adjust the Red black level until bright spots appear on the screen.
The projected image should now be noisy full black
If one uses a gray scale pattern, the bright spots should appear in the black bar.
Performing White input balance
1. Connect the source you want to project.
2. PressMenuto activate the menus and selectImage→Image Settings→Input Balance.
Image 9-37
Main menu, Image
Image 9-38
Image adjustments
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							9. Image
Image 9-39
Image settings, input balance
Image 9-40
Input balance, white balance
3. PressENTERto select.
4. Do you want to use an internally generated test pattern ?
If yes, use the▲or▼key to selectAdjustment Patternand pressENTERto toggle between [on] and [off]
If no, select a white pattern (or gray scale as alternative).
5. Use the▲or▼key to selectWhite balance red.
6. Adjust the red white level (gain) on a minimal value
7. Use the▲or▼key to selectWhite balance blueand adjust the blue white level (gain) on a minimal value.
Note:This minimal value is not necessary , provided that the 2 other colors are not influencing too much the color to be adjusted,
in fact the aim is to minimize the effect of the two other colors since there is a risk of reaching too soon the transition
(bright spots) due to the contribution of these two other colors signals.
8. Use the▲or▼key to selectWhite balance greenand adjust the Green white level (gain) until bright spots appear on the screen.
9. Use the▲or▼key to selectWhite balance blueadjust the Blue white level (gain) until bright spots appear on the screen.
10.Use the▲or▼key to selectWhite balance redadjust the Red white level (gain) until bright spots appear on the screen.
The projected image should now be noisy neutral gray.
How to adjust for an YUV signal
Use a gray bar test pattern
1. Turn the green black balance back to - 20.
2. Adjust the Red black balance until red dots are visible in the black bar.
3. Adjust the Blue black balance until blue dots are visible in the black bar.
4. Adjust the Green black balance untilfirst gray dots in the black bar (only in the black bar, the rest must be mid gray, except the
white bar).
5. If you see multiple or no white bars in stead of one, change white balance for green (higher or lower) until only one bar is visible.
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9.4 Aspect Ratio
Aspect ratio
Relation between the horizontal & vertical dimension in which the window will be displayed, e.g. 4 by 3 or 16 by 9.
Can also be expressed as a decimal number, such as 1.77. The larger the ratio or decimal, the wider the image (or
the less the image is squared).
What can be done?
The aspect ratio setting forces the projector to project an image using a defined aspect ratio.
Aspect ratio Description
4:3
Standard television format
16:9
Wide screen television format / anamorphic format
5:4
Workstation format
2.35
Film format
1.88 Digital cinema 2K aspect ratio
1.85
35 mm US and UK wide screen standardfilm format
1.78
Wide screen television format / anamorphic format
1.67
Europeanfilm ratio (also 1280x768)
16:10
Wide screen cinema format (WUXGA format)
Custom Any custom format can be set up
Some example images:
4/3 signal16/9 RGB signal
Image 9-41
Example images aspect ratio
How to set
1. PressMenuto activate the menus and selectImage→Aspect Ratio.
Image 9-42
Main menu, Image
Image 9-43
Image, aspect ratio
2. PressENTERto select.
3. Use the▲or▼key to select the desired aspect ratio.
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							9. Image
Image 9-44
Aspect ratio
4. PressENTERto activate.
How to set up the custom aspect ratio
1. While Custom is selected, use the▲or▼key to selectSetup Customand pressENTER.
Image 9-45
Custom aspect ratio
Image 9-46
Custom aspect ratio adjustment
The custom aspect ratio setup menu opens.
2. Use the▲or▼key to adjust the vertical size (height) of the image.
Use the◄or►key to adjust the horizontal size (width) of the image.
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							9. Image
9.5 Timings
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							9. Image
9.5.1 Source timings
Adjustable items
• Horizontal start in pixels : number of pixels between the horizontal sync and active video information in the input signal.
• Horizontal Active = Active horizontal pixels (width) : number ofactive pixels in the input signal. This value is normally given in
the source specifications. If not, adjust until full image is displayed (no missing pixels).
• Vertical start in lines : number of lines between the vertical sync signal and active video information in the input signal.
• Vertical Active = Active vertical lines : number of active lines in the input signal. This value is normally given in the specification
of the source. If not, adjust until full image height is displayed (no missing lines).
• Total pixels: Total horizontal pixels in the source. If the value is wrong, sampling mistakes (small vertical bars in the projected
image) will be seen in the image.
• Total lines: Total lines in the source.
How to set up
1. PressMenuto activate the menus and selectImage→Timings.
Image 9-47
Main menu, Image
Image 9-48
Image, timings
Image 9-49
Timings window
2. PressENTERto select.
3. Use the▲or▼key to select a setting.
4. Use the◄or►key to change the value
Or,
pressENTERto open the specific adjustment menu. Follow the adjustment method as described in Navigation and adjust-
ments, page 89.
5. Continue with the other settings in the same way until all timings are set.
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