Apple Final Cut Pro 7 - Manual (Page 1316)

For this reason, as you are performing color correction on clips in your edited sequence,
you need to make sure that the luma and chroma levels of your video stay within the
parameters referred to as broadcast-legal, or acceptable for broadcast. It is easy to
inadvertently push the levels of clips in your sequence too high, so it’s important to use
Final Cut Pro scopes and range-checking options to make sure that the luma and chroma
levels you set stay legal.
Legal Broadcast Colors
A mistake beginners often make when creating graphics for video is to use colors that
are vivid on the computer display, but have chroma and luma levels that are outside of
the “legal” range of color that can be broadcast. Broadcasters must adhere to these
specifications or risk fines from the FCC. Therefore, if you submit a tape with signals out
of specification, it may not be accepted.
Many graphics and compositing applications have a “broadcast safe” filter that you can
use to limit the color range of a graphic so that it will be broadcast properly without
distortion. However, you should use these filters only as a last resort. It’s best to be aware
of the specifications of the video signal and keep your chroma and luma values within
proper limits.
If your program has been accepted for broadcast, you can usually get a set of guidelines
specifying the broadcaster’s criteria for a legal video signal. The Corporation for Public
Broadcasting has a frequently cited set of guidelines for defining what levels of luma and
chroma are acceptable for broadcast. You will probably be in the clear with most
broadcasters if your program adheres to these guidelines, since they are fairly conservative.
Other broadcast companies publish their own guidelines.
1316 Chapter 78 Measuring and Setting Video Levels