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Ebu color bars (8-color full bars), Window 80 – Extron Electronics VTG 400D_400 DVI User Guide User Manual

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VTG 400D/400 DVI • Appendix

The small blue rectangle under the white bar and the small white rectangle under

the blue bar are used to indicate proper threshold of the color control level. While

viewing the blue bars, adjust the color level control until the perceived brightness of

the small rectangles merges with the larger bars to yield one consistent intensity.
Now, adjust the tint control by viewing the small rectangles under the cyan and

magenta bars. Adjust the tint control until those bars merge into one long bar of

consistent intensity. There may be interaction between color and tint, so, alternately

adjust each control using this procedure until the blue bars across the screen are all

of consistent intensity. This ensures proper adjustment of the color decoder. The

inability to achieve an even intensity indicates the presence of color decoder errors.
Note that composite NTSC video utilizes a 7.5 IRE setup pedestal for the black

level. The S-video format is likely to include the setup pedestal depending on the

source system and the methodology for signal creation. The VTG 400 includes the

setup on the S-video luminance signal output and on the component Y channel

output. Digitally-produced component NTSC or decoded NTSC (into the RGB

domain) does not utilize the setup pedestal. This difference can account for a

significant shift of black level when calibrating displays for multiple signal sources

and formats.

EBU Color Bars (8-color full bars)

The EBU color bars are used by European television personnel

transmitting PAL (Phase Alternating Line) television signals. Its

function is identical to the NTSC color bars except that it is made up of

eight single bars with no provision for color saturation setup or

PLUGE. The PAL system, by design, does not require a tint control on the receiver’s

decoder. Therefore, tint calibration is not required. Note that the PAL transmission

standard does not utilize a setup pedestal. Therefore, black level reference in the

signal is consistent regardless of format.

14. Window 80%

Window patterns provide a low duty cycle white, or near white,

reference at screen center for performing grayscale setup without

driving the display into a nonlinear operating condition. In particular,

driving CRT-based projectors with high duty cycle signals causes an

overdrive condition. Therefore, the 80% gray level of this pattern is a good choice

for setup of highlight values when performing grayscale setup of a display where

light output efficiency may not rival that of a direct-view display.
Using the 80% window as the highlight value for performing color of white

measurement with a colorimeter typically does not overdrive the projection system.

When using a colorimeter, or other suitable light measurement device, the gain or

highlight controls are adjusted to provide the correct color of white during

grayscale calibration. The 80% window pattern is located “next door” to the 20%

level window pattern to facilitate quick switching between high and low duty cycle

window patterns in order to streamline the grayscale calibration procedure.