Extron Electronics VTG 400D_400 DVI User Guide - Manual (Page 78)

Appendix, cont’d
VTG 400D/400 DVI • Appendix A-14
15. Window 20%
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. The 20%
gray level of this pattern is a good choice for setup of lowlight values
(those gray levels near black) when performing grayscale setup of a display.
When using a colorimeter, or other suitable light measurement device, the bias or
lowlight controls are adjusted to provide the correct color of gray near black during
grayscale calibration. This pattern is located “next door” to the 80% level window
to facilitate quick switching between high and low duty cycle window patterns in
order to streamline the grayscale calibration procedure. In addition, the 20% level
window is located next to the variable window pattern which may be set to any
value from zero to 100% output level. The default level for the variable window
pattern is 100%.
16. Window (variable level)
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. The variable
window pattern level defaults to 100% output level, or full white.
Using the Up/Down soft keys on the VTG 400, the level of this pattern may be set
in 1% increments to any value required.
For direct-view displays, the 100% window level is normally used to set the
highlight or gain controls when performing grayscale calibration. With this pattern
located next to the 20% window, rapid pattern switching is possible between
highlight and lowlight adjustments when performing the grayscale calibration
procedure.
17. Flat Field
This pattern is used to evaluate white field uniformity. The default
level of this white field is 100%, but may be adjusted using the VTG
400 soft keys to any value from zero to 100% in 1% increments. This
pattern is also used for the measurement of display light output. For
example, with the ANSI methods of measurement for display light output, an
appropriate light meter may be placed at each of the prescribed nine screen
locations in order to obtain readings for entry into the ANSI calculations. See the
Flat Field with Targets test pattern for additional support with this task.
For situations requiring display of any one of the primary or secondary colors as a
flat field, the user may enter into the VTG 400 video setup menu and turn On or Off
combinations of the primary output channels. Also note that this feature is
available to modify the color of most all the test patterns.
18. Flat Field with Targets
Switching to the Flat Field with Targets pattern results in nine box
targets being overlaid upon the flat field pattern. These targets guide
the user with proper location placement of the appropriate light
metering device for collection of light output levels used in calculation
of the ANSI lumen value of the display. The targets facilitate location of the light
meter only and should be switched Off (returning to the regular flat field pattern)
while taking the light measurement reading.