GME HG139, User Manual

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PLUGE
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0 +5 0/-5 0 +50
The PLUGE (stands for Picture Line-Up Generation Equipment) pattern is divided into two
halves.
The left half consists of 2 vertical stripes against a black background, i.e. 7.5 IRE for NTSC
and 0 IRE for the other patterns. The left stripe is fixed at a brightness level slightly whiter
than black (12.5 IRE for NTSC and 5 IRE for the other video formats). The right stripe
alternates between black and slightly blacker than black (7.5/2.5 IRE for NTSC, 0/-5 IRE for
the other video formats).
The right half of the pattern is fix at 57.5 IRE for NTSC and 50 IRE for the other formats.
Note : the IRE values for NTSC is different from the other formats by 7.5 IRE due to the 7.5
IRE setup for the NTSC format.
The PLUGE pattern is used to calibrate the black level on a display device. Black level
basically refers to the brightness of the darkest areas in the picture. Adjust the appropriate
controls on the display device (i.e. brightness and contrast controls, etc.) to calibrate the black
level on the device. Refer to the following when making calibration:
♦
The left vertical stripe is just visible as a dark gray.
♦
The right vertical stripe alternates between black and slightly blacker so should not be
visible against the background. If blinking can be seen on this vertical stripe, it means
the brightness of the display is set too high. Lower the brightness level until the
blinking barely disappears.
♦
The right half of the pattern is a lighter gray and should be clearly visible.
This pattern is also useful for checking DC restoration (black clamping) performance of a
display device. If a display device has good DC restoration, its black level control can be
adjusted on either a low API (average picture level) or high APL pattern, with no change in
black level as you switch from one pattern to another. Display device with less than perfect
DC restoration will exhibit alternating changes of brightness in the black background and the
+10 IRE vertical stripe. This is due to the display device’s inability to perfectly clamp black
to a fixed level. This can be determined when the brightness level is adjusted slightly above
normal setting. If the brightness level of the two vertical stripes remains constant as the right
stripe blinks (alternating between black and slightly blacker than black), the display has good
DC restoration.