On the WFM700 series, WFM6xxx/7xxx series and the WVR6xxx/7xxx series instruments you can enable a picture brightup feature which will show a sort of checkerboard or zebra pattern on top of the picture in locations that are outside legal gamut ranges. The exact process to enable this feature varies from instrument to instrument but is generally found in the configuration menu and the process is described in each unit's respective user manual. You can see an example of this gamut overlay on the SMPTE color bars shown below: Without gamut brightups: With gamut brightups: