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NotTaR of Television Sets : What is Kell factor with respect to inte..
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(The following is from Bob Myers (myers@fc.hp.com).)
The Kell factor - which has to do with the fact that we're often undersampling
an image from the standpoint of the Gospel According to St. Nyquist - IS
a factor in the reduction of vertical resolution, but interlacing plays
a part as well. This comes from at least two factors:
- The receiver usually cannot precisely interleave the two fields.
- More importantly, there are steps taken to reduce the interline flicker
which reduce the effective vertical resolution. This includes running the
line width of the display somewhat larger than would otherwise be the case,
and in interlaced cameras, discharging the entire screen (including the
lines from the "other" field) after every field scanned.
Interlace is particularly troublesome on moving images, where you will often
perceive momentarily "missing" details. There was a LOT of discussion
regarding the gory details of interlacing in the recent HDTV debates within
SMPTE and other groups.