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Reference
WFM700 Series Waveform Monitors User Manual
3-27
Gamut Measurements
NOTE. Gamut error detection is disabled in Eye and Jitter display modes.
The waveform monitor features three types of gamut displays:
H The Diamond display shows the relationship between the R, G, and B video
signals. The waveform monitor converts the Y, P
b,
and P
r
components of the
signal into R, G, and B to form the Diamond display.
H The Split Diamond display separates the upper and lower diamonds to show
excursions below black; otherwise it is identical to the Diamond display.
H The Arrowhead display checks that signals conform to legal composite
gamut space.
NOTE. Refer to the reference document A Guide to Standard and High-Definition
Digital Video Measurements at the Tektronix, Inc. Web site (www .tektr onix.com)
for information about how the Diamond and Arrowhead displays are created
and for information about defining legal and valid gamut signals.
Use the Diamond or Split Diamond displays to check RGB gamut. For a signal
to be in gamut, all signal vectors must lie within the G-B and G-R diamonds.
The direction of an excursion out of gamut indicates which signal is excessive.
Errors in green amplitude affect both diamonds equally, while blue amplitude
errors affect only the top diamond and red errors affect only the bottom diamond.
Use the Split Diamond display to see excursions below black in either of the
G--B or G--R spaces.
The intensity of a vector indicates its duration. A momentary out-of-gamut
condition appears as a faint trace. Long duration violations show as a bright
trace. Figure 3--10 shows out-of-gamut signals on the Diamond display.
Monochrome signals appear as vertical lines. Nonlinear component processing,
such as from a gamma corrector that alters white balance, can cause deviations
along the vertical axis.
Bending of the transitions indicates timing delays. When a color bar signal is
applied, the vertical axis becomes an indicator of delay errors. The Diamond and
Split Diamond displays allow you to visualize interchannel timing errors. Use
the Lightning display in Vector mode to quantify the amount of timing error.
The Diamond and Split Diamond graticules have marks to indicate conformance
using 75% color bars. The edge of the diamond is used for 100% color bars.
Checking RGB Gamut