Rigol DS2000E Series User Manual page 106

RIGOL
Tips
For a better observation of the waveform details in the video signal, you can

set a larger memory depth first.
In the trigger debugging process of video signals, the frequency in different

part of the signal can be reflected by different brightness as RIGOL digital
oscilloscopes provides the multi-level gray scale display function.
Experienced users can quickly judge the signal quality and discover
abnormalities.
5-24
Chapter 5 To Trigger the Oscilloscope
DS2000E User's Guide