Primary Color Correction: Color Control Primer - The Art and Technique of Digital Color Correction - page 98

Fig. 3.33 This image shows the contextual menu that opens if you right-click on a scope in the Apple Color UI, allowing you to switch to
a histogram.
Fig. 3.34 The uncorrected histogram. Notice that each color channel starts and stops in a different hori-
zontal position. To balance this shot, each channel should start and stop at the same horizontal position.