Tektronix WFM 601i, User Manual

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Measurement Applications
3–18
WFM 601i Serial Component Monitor
Note that since R, G, and B can independently assume any value between 0 V
and 700 mV, the “in RGB Gamut” is described by squares in each of the two
X–Y plots. When rotated, the squares produce two diamond-like shapes that
show the legal RGB space.
For a signal to be in Gamut, all signal vectors must lie within the diamonds.
Conversely, if a vector extends outside the diamond, that signal is out of gamut.
The intensity of the vector indicates its duration; therefore, a momentary
out-of-gamut condition will show as a faint trace. Long duration violations will
show as a bright trace. The video operator can then determine which violations
are significant and in need of correction.
When an out-of-gamut condition exists that requires correction, the Diamond
display can aid in determining which component (R, G, or B) is out, and in
which direction. By remembering that Diamond is just two rotated X–Y plots,
and using the labeled axis that appear on the electronic graticule, it quickly
becomes apparent how to correct the signal. Figure 3-9 gives some sample
out-of-gamut signals displayed with Diamond.
G > 700 mV, B and R OK.
B
R
G
G
B > 700 mV, G and R OK.
B
R
G
G
B < 0 V, G and R OK.
B
R
G
G
R is just slightly above 0 V.
G is about 350 mV.
Figure 3-9: Out-of-Gamut signals as displayed by Diamond.
The Lightning display plots luminance against each of the color difference
components. It should be used when manipulating signals by varying the
luminance and color difference components. Diamond is the best choice when
manipulating signals with R, G, and B controls.
Checking Gamut
Correcting Gamut
When to Use Lightning