Apple Color 1.5 - Manual (Page 233)

The following example shows this principal in action. If you adjust the Highlight color
balance control to add blue to a linear gradient, you'll see the following preview.
As you can see, this change affects both the whites and midtones. If you want to restrict
the correction that's taking place in the midtones, while leaving the correction at the
upper portion of the whites, you can take advantage of the technique of using
complementary colors to neutralize one another, making a less extreme, opposite
adjustment with the Midtone color balance control.
The result is that the highlights correction that had been affecting the midtones has been
neutralized in the lower portion of the midtones.
Although making opposing adjustments to multiple color balance controls may seem
contradictory, it's a powerful technique. With practice, you'll find yourself instinctively
making adjustments like this all the time to limit the effect of corrections on neighboring
zones of tonality.
233 Chapter 9 The Primary In Room