Apple Final Cut Pro 6 - Manual (Page 1390)

Chapter 27 Color Correction 605
III
 View Final/Matte/Source button: This button has three states:
 Final: The default state (a gold key against a gray background) allows you to see
the end result—the effect happening within the keyed area.
 Matte: The second state (a black key against a white background) displays the
key itself as a grayscale image, so you can fine-tune it without being distracted
by the image.
 Source: The third state (a gold key against a blue background) shows only the
original video image.
 Invert Selection button: Click this button to invert the key you’ve defined. For
example, if you’ve set up a key based on the color of a green car and turned the
desaturation all the way down so that the car is grayscale and the background is
color, clicking the Invert Selection button makes the background turn grayscale, and
the car appears in color.
Using Multiple Filters Together with the Limit Effect Controls
You can use the Limit Effect controls to layer multiple color correction filters onto a
single clip, selectively balancing specific areas of your picture based on their color,
saturation, and luma levels. Color correction filters work serially, the same as any
other filters. This means that if two color correction filters are applied to a single clip,
the second color correction filter works on the modified output of the first filter,
rather than on the original color values of the image.
For example, if you add a filter that adjusts the color in a group of flowers but causes
the green grass in the background to look too red, a second color correction filter
using the Limit Effect controls will target the greenish red color of the grass as it has
been modified, rather than the original green values.