Apple Final Cut Pro 7 - Manual (Page 1462)

About Bit Depth and 32-Bit Floating-Point Processing
Final Cut Pro supports high-resolution video processing of Y
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sequences by performing
calculations in 32-bit floating-point number space. Compared to 8- and 10-bit integer
calculations, 32-bit floating-point numbers have an extremely high level of precision,
which helps to avoid rounding errors that can accumulate as you add more layers to a
composite or add multiple filters to a clip. In most cases, you should choose to render
your sequence using 32-bit floating-point space (called high-precision YUV ) for final
rendering before output or export.
When using the Y
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color space, Final Cut Pro supports either 8- or 10-bit video media
files. To determine which color space and bit depth your video interface supports, see
the documentation that came with the interface. For more information on which filters
and transitions support 10-bit resolution, see
“Video Filters Available in Final Cut Pro” and
“Refining Transitions Using the Transition Editor.”
Maximum RGB White Level Settings
When you add graphics or generator clips created in the RGB color space (for example,
imported graphics files or generator clips created with generators such as the Text
generator), the “Process Maximum White as” pop-up menu determines whether the
maximum white value of these clips should be 100 percent or 109 percent. Use this
pop-up menu to make sure the white levels of your RGB footage match those of your
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video. Because most still images and generators use the RGB color space and most
video footage is recorded in the Y
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color space, it is important to check this pop-up
menu whenever you add graphics to your sequence.
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and RGB video systems assign maximum white levels to different digital codes, as
shown here with an 8-bit video example.
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8-bit value RGB 8-bit value Percentage Description
1-15 n/a -7% Super-black
16 0 0% Black
235 255 100% White
236-254 n/a 109% Super-white
A 100 percent white value in Y
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video is the legal limit for broadcast television and
generally corresponds to the analog broadcast legal limit of 100 IRE. However, camcorders
and decks allow white levels above this level (up to 109 percent) to avoid clipping
occasional highlights. For example, even if you set your camcorder exposure so that it
appears no level is above 100 percent, highlights from shiny objects can go beyond 100
percent. Having the extra headroom from 100 percent to 109 percent allows you to
capture these highlights without losing details in the white.
1462 Chapter 85 Rendering and Video Processing Settings