Re: Went out to buy small LCD Tv, and did not.
- From: "Stephen" <stephen@xxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 27 Apr 2006 02:03:58 +0100
http://groups.google.com/group/uk.tech.digital-tv/browse_thread/thread/79d29I think the major drawback with LCDs is line averaging [snip][snip]
a CRT which does not have a fixed number of lines in the first place
If your PC has an LCD monitor [snip]
The first plonker (for why see my replies in this thread):
http://tinyurl.co.uk/c76l
... standing in for ...
213846ee51b/eccaf1236f8116e9?lnk=st&q=group%3Auk.tech.digital-tv+insubject%3
Alcd+insubject%3Atv+insubject%3Apictures&rnum=1&hl=en#eccaf1236f8116e9
The link says, "You can argue that Trinitron CRTs have a native resolution
of a sort - horizontally only because it has vertical lines. Some
contradiction surely? Note: Horizontal Dot Pitch, Trio Dot Pitch, Optimal
Resolution Settings."
CRT's do not employ line averaging in connection with the dot pitch. CRT's
scan the same number of horizontal lines as the TV signal to which they are
synchronised, so they do not have a native resolution in the same sense that
LCDs and Plasma screens do. You could argue that a CRT's native resolution
varies to match the TV signal to which it is synchronised. Dot pitch on a
CRT TV refers to a vertical line pattern which does not conflict with the
horizontal scan lines. LCDs have both a vertical and a horizontal line
pattern, and their horizontal pattern conflicts with the horizontal TV scan
lines. LCDs blur the TV picture to get around this conflict. CRTs do not.
CRT's do not have a fixed number of scan lines. For example when I play an
NTSC DVD my CRT TV scans 480 active lines instead of the usual 576. These do
not conflict with any other structure of horizontal lines on the screen, as
they would if I used a standard 768 line LCD.
The comparison between LCD TVs and LCD PC monitors is valid since they are
very similar displays, with usually the same number of horizontal lines, and
when they display pictures of non-native resolution both PC and TV monitors
use the same blotchy kind of line averaging. The effect can be reproduced in
Photoshop by blurring an image and then sharpening it again after some of
the picture information has been lost by blurring. It has a characteristic
effect on text, which is to join adjacent letters together with a sharp
edged blob. It changes the shape of text letters. This kind of error can be
clearly seen on most LCD screens with the BBC News 24 DOG. The only way to
get round it is to reduce the LCD sharpness setting from it's default value
to zero, which then shows up the blurring of the LCD display in all it's
glory. The use of 768 line fixed resolution displays for 576 and 1080 line
TV pictures is a cheap and shoddy shortcut which cannot reproduce TV
pictures correctly. I suspect that it is only done because flatscreens were
originally designed for PCs then bodged for TV. In future years we will look
back on today's flatscreens with ridicule: so called HDTVs which can't
display 1080 lines at all, and look softer than a SD CRT when displaying SD.
.
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