Apple Color 1.5 - Manual (Page 193)

The Luma Scope
The Luma scope shows you the relative levels of brightness within the image. Spikes or
drops in the displayed waveform make it easy to see hot spots or dark areas in your
picture.
The difference between the highest peak and the lowest dip of the Luma scope’s graticule
shows you the total contrast ratio of the shot, and the average thickness of the waveform
shows its average exposure. Waveforms that are too low are indicative of images that are
dark, while waveforms that are too high may indicate overexposure.
Overexposed waveform
Underexposed waveform Well-exposed waveform
If you’re doing a QC pass of a program with the Broadcast Safe settings turned off, you
can also use the scale to easily spot video levels that are over and under the recommended
limits.
193 Chapter 8 Analyzing Signals Using the Video Scopes