Tektronix WFM8200 - Checking Gamut

Checking Gamut
Checking Gamu
t
Signals that
are legal and valid in one signal representation may not be legal in
another representation. Specifically, signals which are legal in the Digital YCbCr
representation may not be legal if transcoded to RGB or encoded to NTSC / PAL.
Any signal that fails this test is considered out of gamut.
Adjust Gamut Thresholds from the Configuration menu. From this same menu,
you can als o reset some gamut thresholds to default values.
Your instrument supports multiple displays and alarms to detect out-of-gamut
signals. The flexible, tiled display allows you to simultaneously view several
gamutmeasurementstolearnwhichismost appropriate for a given application.
The displays are and their uses follow:
Diamond for checking that SDI signals conform to legal RGB gamut space.
Split Diamond separates the upper and lower diamonds to show excursions
below black; otherwise it is identical to the Diamond display.
Arrowhead for checking if an SDI signal is legal for composite color space.
Composite Waveform modes for checking both SDI and composite signals
for legality in composite color space.
Spearhead for showing lightness, color value, and saturation o f the RGB
color space.
Diamond, Split Diamond, Arrowhead, and Spearhead have adjustable thresholds.
If the signal goes outside the area defined by the thresholds, the signal is out of
gamut. If these limits are exceeded, then the instrument can generate alarms
if configured to do so. For composite waveforms, the legal limit is simply the
maximum level allowed for the combination of luma and chroma. This limit
depends on the application. For example, a video tape machine m ay be able to
record and play out signals with higher luma and chroma components than a
transmitter.
To Set U p Gamut Checks
1. Connect a video signal to an input on the rear panel. Make sure to terminate it
properly if it requires termination.
2. Select a tile in which to view the Gamut Display and press and hold the
GAMUT button.
3. In the Gamut pop-up menu, select from the following gamut display types:
Diamond – Use to detect, isolate, and correct RGB component gamut
errors. (See page 120, Checking RGB Gamut.)
Split Diamond – Use to reveal hard-to-find black gamut errors.
WFM8200 and WFM8300 Waveform Monitors 119