Apple Final Cut Pro 7 - Manual (Page 1394)

Because the clip was tinted toward the reds, when you click the eyedropper in the white
piece of scenery outside the window, the Whites color balance indicator moves into a
mixture of blue and cyan and turns the whites of the image into true white.
The Whites color balance
indicator moves to
correct the whites.
You can see the correction in the Canvas.
Before After
Note: When using the Whites Auto-Balance eyedropper, it’s important to recognize that
the color temperature of the light illuminating the white area you select will affect the
hue of the compensation that is made. If the picture is lit with a combination of daylight
and tungsten sources, selecting a part of the picture illuminated by daylight will result
in compensating the overall color temperature of the image by adding more reds, whereas
selecting a part of the picture illuminated by tungsten will result in adding more blues.
In such a case, you need to simply pick the best possible compromise that looks right to
you.
Next, you’ll focus on the blacks in your image, making further adjustments for more
accurate colors.
1394 Chapter 82 Color Correction Examples