DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

Luma/color difference component sets
These color difference component sets, all based upon
B’–Y’ and R’–Y’, are in use:
• Y’P BP R coding is used in component analog video; P B
and P R are scaled to have excursion nominally identical
to that of luma. Y’P BP R can be potentially based upon
any of three sets of luma coefficients: Rec. 601 for
SDTV, SMPTE 240M (“interim implementation”) for
HDTV, or Rec. 709 for HDTV. In 480i29.97 SDTV, three
different analog interface standards are in use: EBU N10
“SMPTE,” Sony, and Panasonic.
• Y’C B C R coding is used for component digital video; C B
and C R are scaled to have excursion 224 ⁄219 that of
luma. A “full-range” variant is used in JPEG/JFIF. Y’C B C R
can be potentially based upon Rec. 601, SMPTE 240M,
or Rec. 709 luma coefficients.
In NTSC and PAL chroma modulation, on page 335, I will
detail two additional component sets, whose proper
use is limited to composite NTSC and PAL SDTV:
• Y’UV components are only applicable to composite
NTSC and PAL systems. B’–Y’ and R’–Y’ are scaled so as
to limit the excursion of the composite (luma plus
modulated chroma) signal. Y’UV coding is always based
upon Rec. 601 luma coefficients.
• Y’IQ components are only applicable to certain
composite NTSC systems. UV components are rotated
33°, and axis-exchanged, to enable wideband-I transmission.
This is an obsolete technique that is rarely, if
ever, practiced nowadays. Y’IQ coding is always based
upon Rec. 601 luma coefficients.
The bewildering set of scale factors and luma coefficients
in use is set out in Table 24.2A opposite for
analog SDTV, Table 24.2B overleaf for digital SDTV and
computing systems, and Table 24.2C for analog and
digital HDTV. The following two chapters detail component
color coding for SDTV and HDTV, respectively.
298 DIGITAL VIDEO AND HDTV ALGORITHMS AND INTERFACES