Apple Final Cut Pro 7 - Manual (Page 1459)

Changing Settings in the Video Processing Tab
The Video Processing tab determines how clips’ media files are processed and rendered
within your sequence. This affects color space conversions, maximum white level, bit
depth, and the quality of motion parameter adjustments.
Color space and
bit depth settings
Maximum RGB white
level settings
Motion filtering quality
Rendering Y
′
C
B
C
R
Footage in the RGB Color Space
When super-white Y
′
C
B
C
R
values are converted to RGB, any values above 235 are mapped
to 255. Any variation in luma above 235 is therefore clamped, or clipped, resulting in solid
patches of white where there was once detail in the bright parts of the image. If these
RGB values are converted back to Y
′
C
B
C
R
, all white values of 255 are mapped to a single
value (usually 235, which is white in Y
′
C
B
C
R
). The newly converted white values are lower
than the white values originally captured, causing areas of the picture that had super-white
values to darken slightly and to appear flat where there was once detail in the highlights.
This is known as luma clamping. You can avoid this by editing your Y
′
C
B
C
R
footage natively
in the Y
′
C
B
C
R
color space.
Choosing RGB Versus Y
′
C
B
C
R
Color Space
Each color space has a certain range, or gamut, of colors that can be represented. Some
colors represented in the Y
′
C
B
C
R
color space cannot be represented in RGB and are said
to be out of gamut. If the color space of your media files doesn’t match the color space
of your sequence, Final Cut Pro maps the media file color values to the color space of the
sequence. In some cases, colors get “clipped” to the nearest value during conversion. This
can cause very saturated colors to become less intense and is referred to as chroma
clamping.
1459 Chapter 85 Rendering and Video Processing Settings