Apple Final Cut Pro 5 - Manual (Page 1220)

Chapter 20 Color Correcting Clips 433
II
The Parade scope is very useful for comparing the relative levels of reds, greens, and
blues between two clips. If one clip has more blue than another, the difference shows
up as an elevated blue waveform in the one, and a depressed blue waveform in the
other. In the previous screenshot, the overall image contains quite a bit of blue. By
comparison, the shot of the couple dancing below has substantially less blue and far
higher levels of red, which can be seen immediately in the Parade scope.
How the Final Cut Pro Scopes Work
The more technically minded may be interested in knowing that the scopes in
Final Cut Pro (with the exception of the Histogram) work by sampling 16 lines of
video from the Viewer or Canvas. If you’re using a codec capable of Y´C
B
C
R
processing,
the scopes display the Y´C
B
C
R
information for the currently displayed clip. Otherwise,
the scopes display an RGB conversion of your image’s information.
These 16 lines are evenly distributed from the top of the video image to the bottom,
within the action safe area of standard definition video. This means that they sample
approximately every 27th line of video. This is sufficient to catch video elements
whose height equals 5 to 10 percent of the total size of your image.
This image contains
much less blue than
the previous image.