DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

information rate of the color difference components without
perceptible degradation. Usual color-difference pairs are [B’-Y’,
R’-Y’], [C B , C R ], [P B , P R ], [I, Q], and [U, V].
Color standard The parameters associated with encoding of color information –
for example, R’G’B’, Y’C BC R, or MAC component video standards,
or NTSC, PAL, or SECAM composite video standards. Distinguished
from scanning standard (see page 646).
Color subcarrier 1. A continuous sine wave signal at about 3.58 MHz or 4.43 MHz
used as the basis for quadrature modulation or demodulation of
Chroma (3) in an NTSC or PAL composite video system. See also
Burst, on page 616.
2. Color subcarrier (1), onto which two color difference signals
have been imposed by quadrature modulation. Properly, modulated
chroma.
Color temperature Characterization of an illuminant or a white reference in terms of
the absolute temperature (in units of kelvin) of a black body radiator
having the same chromaticity.
Color-under A degenerate form of composite analog NTSC or PAL video
recording wherein modulated chroma is heterodyned onto
a subcarrier whose frequency – roughly 1 ⁄6 of the NTSC or PAL
color subcarrier frequency – is crystal-stable but not coherent with
line rate. The heterodyning process destroys the phase relationship
of color subcarrier to sync, and severely limits chroma bandwidth.
The technique is used in U-matic ( 3 ⁄4-inch), VHS, S-VHS,
8 mm (Video-8), and Hi8 videocassette recorders.
Comb filter 1. Generally, a filter having magnitude frequency response with
periodic equal-magnitude maxima and minima.
Combination N/PAL See CN/PAL, on page 618.
Common data rate See CDR, on page 617.
2. In video, a comb filter (1) incorporating delay elements with
line, field, or frame time duration.
3. In a composite NTSC video decoder, circuitry incorporating one
or more line delay elements (linestores) to exploit the frequency
interleaving of modulated chroma (1) to separate chroma from
luma. A comb filter provides better separation than a notch filter,
owing to its suppression of cross-color and cross-luma artifacts.
4. In a composite PAL video decoder, circuitry incorporating a line
delay element (linestore) to separate the modulated U chroma
component from the modulated V chroma component.
Common image format See CIF, common image format, on page 618.
Component (adj.) In video, a system that conveys three color values or signals independently,
free from mutual interference. Examples are R’G’B’,
620 DIGITAL VIDEO AND HDTV ALGORITHMS AND INTERFACES