Checking Gamut
Checking Gamut
Signals that are legal and valid in one signal representation may not be legal in another representation. Specifically, signals
that 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 for these color spaces.
The waveform monitor supports multiple displays and alarms to allow detecting out of gamut signals. The flexible tile
display allows you to simultaneously view several of the gamut measurements to learn which is most appropriate for a
given application. The displays are:
Diamond for checking that SDI signals conform to legal RGB gamut space (which appears as a Split Diamond on the
WFM6100/WFM7000/WFM7100 monitors, and separates the upper and lower diamonds to show excursions below black)
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
Diamond and Arrowhead 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 waveform monitor 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 application. For example, a recording on a tape may be able to handle a larger signal than if
driving into a transmitter.
The waveform monitor also provides “brightups” for checking gamut. Brightups, or contrast patterns, appear on areas of the
Picture display that are out of gamut as defined by the different threshold settings. Brightups can be displayed for RGB
gamut errors, Composite gamut errors, and Luma gamut errors. To set thresholds for brightups, adjust the thresholds in the
Diamond and Arrowhead displays.
Setting up for Gamut Checks
1.
Connect a signal containing color bar
information.
For set up purposes, the use of a color
bar signal is suggested, but these
displays are useful on all signals.
2.
Press the IN/OUT button to display the
IN/OUT menu.
3.
Select the input corresponding to the
signal connected.
Quick Start User Manual
105
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