DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

Level 1. In video, generally, the amplitude of a video signal, or one of its
components, expressed in volts, millivolts, IRE units, or digital
code value.
2. In JPEG, MPEG, and DV compression, the magnitude (i.e.,
absolute value) of a DCT coefficient.
Lightness CIE L*: An objective quantity related to brightness; approximately
equal to relative luminance raised to the 0.4-power.
Line, active;
Line, picture
A scanning line that is specified by a scanning standard to contain
picture. (Exceptionally, in 480i systems, closed caption lines are
considered to be “active.”)
Line frequency 1. In video, the frequency of horizontal scanning; about 15.7 kHz
for SDTV, and 33.7 KHz or higher for HDTV.
2. AC power line (mains) frequency, typically 50 Hz or 60 Hz,
usually similar to the vertical scan frequency.
Line frequency should be used with care in video because it may
refer to the frequency of horizontal scanning, or to AC power
(mains) frequency, which is usually similar or identical to the
frequency of vertical scanning.
Line-locked 1. In digital video, having an integer number of samples per total
line: If 0 H were digitized, it would take the same value every line.
A line-locked system has coherent sampling and line frequencies,
as in Rec. 601 or 4f SC NTSC. Owing to the +25 Hz offset of the
PAL subcarrier in PAL-B/G/H/I and PAL-N, PAL sampled at 4f SC is
not line-locked.
2. In industrial or security video, having vertical scan frequency
locked to the AC power line (mains) frequency.
Line sync The sync signal pulse that defines the start of a scan line. In 480i
and 576i systems, line sync may be the start of a normal sync or
the start of certain equalization or broad pulses. See also 0 H
datum, on page 609.
Line time The time interval from the 0 H datum of one line to the 0 H datum
of the next. In a digital system, from EAV to EAV.
Linear-light (adj.) Proportional to intensity. Video signals are ordinarily not
conveyed in linear-light form; instead, they are gamma-corrected.
Lines 1. Total number of lines per frame, L T.
2. Active lines, L A .
3. A unit of resolution; properly, TV lines per picture height,
TVL/PH (see page 649).
GLOSSARY OF VIDEO SIGNAL TERMS 635