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6.7.2 Analogue Ys’ Pb’, Pr’: Video Input Offset Adjustment
To set optimum black and colour levels, and for correct
operation of the exposure meter (Section 6.8), analogue video
input offsets should be adjusted to match the particular
camera in use. These adjustments, which should be checked
regularly, are contained within the Diagnostics Menu.
Adjustments should be made with the specific camera in use,
and only once it has been allowed to stabilise in the operating
environment and with its black level suitably adjusted.
Selection of a nominal black image or area within an image
is critical to optimum adjustment of the black level, Y video
input. Either cap-off the camera lens to provide the current
nominal black level or use an internally generated test
pattern. In the latter case, determine which of the areas of
the test pattern corresponds to nominal black as captured
through the lens.
Critical adjustment of Y offset is best accomplished using Y
Monitor (Section 6.8). This is not the case for Pr and Pb
offset adjustments, which must be undertaken with ‘Colour’
mode selected (Section 6.8).
•
Switch the viewfinder to Y Monitor mode (Section 6.8)
Y offset adjustment method:
This adjustment method is based on use of the SMPTE HD
colour bar test chart. The corresponding NTSC chart,
which has different levels in its PLuGE chips, should not be
used in this adjustment method.
•
With the viewfinder connected and camera on, select test
pattern “colour bar with PLuGE” from the camera
•
Rotate then press the MENU control to select Y within the
Diagnostics Menu. The parameter changes to inverse text
to indicate it is selected
•
Adjust Y offset by rotating the MENU control
•
Press the MENU control to accept the current Y offset
