Peak Detector - Christie roadie 25k User Manual

OPERATION
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Roadie 25K User's Manual
When using certain RGB sources, you may need to adjust the normal gain or offset of
odd pixels in relation to even pixels. This will smooth out very narrow (1-pixel wide)
"checks" or vertical stripes that indicate adjacent "on" and "off" pixels. Although
offset and gain slidebars can be adjusted individually and manually, using the Level
Detector simplifies this process (see Figure 3.23):
Use an external analog native-sized continuous grayscale test pattern with at least
1)
256-levels.
Turn "Level Detector" on.
2)
Set "Level Value" to ~200. The image should now be black-and-white (or black-
3)
and-one color, if you use "Color Enable" function).
Adjust offset. Half of the pixels will move, the other half will not.
4)
Adjust until the two transition regions overlap. The stripe of noise will be
5)
minimized, defined by the value in the slidebar.
Set "Level Value" to ~800. The image should now be black-and-white.
6)
Repeat Steps 4 and 5, but adjusting gain.
7)
Repeat Steps 3-7 for all remaining colors. Your RGB source should now be OK.
8)
Figure 3.23. Using "Odd Pixel Adjustment"
NOTES: 1) Adjust offset before gain, since offset affects gain. 2) A value of 128
represents no change in normal odd pixel offset or gain. 3) Odd Pixel Adjustment
eliminates "1 pixel on, 1 pixel off" patterns only, not any type of larger patterns.
Reserved
No function.

Peak Detector

The Peak Detector is fast method of defining individual input levels, and can improve
the accuracy of input levels set by the Auto Input level function. Enabling the Peak
Detector activates a special operating mode for detecting only pixels that are
considered black or white—all other levels are displayed as a mid-level gray. When
used with a 16-step grayscale pattern in which the two black and white bands are
known to be at opposite edges of the image, you can watch these isolated areas while
adjusting individual blacklevels and input drives until both bands are just visible.
Images from this source will then display correct blacks and whites without crushing
or washing out.