Apple Final Cut Pro 7 - Manual (Page 1307)

With the Waveform Monitor set to display saturation, you can compare the relative
saturation levels of two clips by comparing the thickness of their displayed waveforms.
Modifying the saturation of one clip to match that of another is simple; just adjust the
Saturation control of one of the color correction filters in one of the clips to compensate.
An image with high saturation
An image with low saturation
1307 Chapter 78 Measuring and Setting Video Levels