DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

ITU-R Rec. BT.471, Nomenclature
and description of colour bar signals.
Fully saturated R’G’B’ components of colorbars take
R’G’B’ (or RGB) values of zero or unity, independent of
the chromaticity of the primaries: Owing to differences
in primary chromaticities, the exact colors of the bars
are not identical among SMPTE, EBU, and HDTV standards.
Colorbar notation
I have referred to 100% and 75% colorbars. Several
additional variations of colorbars are in use, so many
that an international standard is required to denote
them. A colorbar signal is denoted by four numbers,
separated by slashes. The first pair of numbers gives the
maximum and minimum values (respectively) of the
primary components in uncolored bars – that is, the
black or white bars. The second pair gives the maximum
and minimum primary values (respectively) in the six
colored bars.
The 100% bars, described earlier, are denoted
100/0/100/0. That variation is useful in the studio, in
all forms of component video, and in PAL transmission.
In 480i systems where 7.5% setup is used, 100% bars
refers to 100/7.5/100/7.5. That variation is useful in the
studio. However, as I explained on page 536, terrestrial
NTSC transmission cannot handle 100% bars. NTSC
transmitters are tested using 75% bars with setup,
denoted 100/7.5/75/7.5. Japan uses 480i video with
zero setup; there, 75% bars, denoted 100/0/75/0, are
used.
Frequency response
Magnitude frequency response of a video system can be
tested using a frequency sweep signal comparable to
the one sketched in Figure 7.1 on page 66. Usually,
a multiburst signal having several discrete frequencies is
used instead; see Figure 45.13, on page 545.
Differential gain (DG)
I introduced Linearity on page 21. A system is linear iff
this condition is satisfied:
g( a⋅ x + b⋅ y) ≡ a⋅ g( x) + b⋅ g ( y) [for scalar a, b]
Eq 45.1
CHAPTER 45 SDTV TEST SIGNALS 539