resolution

appledell

Standard Member
can anyone explain the difference in resolutions of various LCD screens.

I am interested in buying a 23 inch Lcd. I have narrowed it down to the JVC, Sony Or Panasonic.

The Panasonic has a much lower resolution than the other two but gets great reviews ??
 

LV426

Administrator
Staff member
I can give you the theory and its theoretical effect. But, as with all things, you have to decide for yourself what you think of the PQ.

A PAL TV signal (whether from off-air, DVB, $ky or DVD etc) has 576 lines of picture information.

Flat panel displays all have a fixed native resolution. The smaller or second of the two measures is the number of rows of pixels.

Question: How do you get 576 lines of detail into 480, or 720, or 768 (or whatever) rows of pixels?

Answer: All flat panel devices have a scaler on board. What this does, effectively, is store up the incoming signal, and then recalculate the best colour for each pixel on the display. Which doesn't, of course, co-incide with the lines in the incoming signal.

So, for example, if a given pair of lines in the signal is such that one is 100% black, and the next is 100% white, the scaler may decide that the best way to handle this is to actually colour the row that is exactly where this edge should be, a shade of grey.

This then begs the question: Is it better to upscale (increase the resolution) or downscale (decrease the resolution) of the signal.

And the theoretical answer is - it is always better to upscale, provided it is done well. The human perception is well practiced at dealing with things that are slightly out of focus (softish) but is not practiced at all from dealing with square pixels - because they don't appear in nature. So an upscaled image, although it doesn't actually have any more detail in it, looks as though it does. But it may look slightly soft.

Conversely, a coarse resoltion screen gives a fake impression of sharpness because what you actually see (and mentally believe is clarity) is the fine black grid that is the space between the pixels.

The greater the screen's resolution, the finer (and hence less visible) this grid is.

To put it another way, a <anything> x 480 screen has to degrade a PAL TV signal in order to display it. A <anything> x <anything greater than 576> screen will upscale the signal, not losing anything, and offering perceived (but not real) gains.

For interest, however, NTSC video has 480 lines - so the scaling on a <> x 480 screen is much simpler and results in no loss or subjective gain.

As for your choices - the Panny suffers another shortcoming which may or may not be of any interest - it has a very poor viewing angle below the horizontal, so it needs to be watched from straight ahead or above.
 

appledell

Standard Member
thanks Nigel, a well informed reply.

I think I will hold off buying for a while until the Lcd has caught up with CRT.
 

LV426

Administrator
Staff member
Interesting comment - 'caught up'.

In many respects, LCD screens are intrinsically (and always have been) better than CRT. Areas of natural superiority include:

Geometry
Convergence
Stability
Size
Resistance to static images (burn in)
Power consumption
etc.
 

appledell

Standard Member
sorry for delay, been away.

What I should have said was I will wait until lcd screens get better resolution and have got rid of all ghosting, jagged edges and smearing etc.

I dont want to be in the same position that I found myself in a few years ago when I bought a Toshiba picture frame tv. (usual 100 hz artifacts. ) only to find that 6 months down the line they include progressive scan.

I agree with you on convergence though.
 

richard plumb

Distinguished Member
what jagged edges?

I think the new philips coming later this year (maybe to the UK too), will have slightly higher res on the bigger screens, but not sure about the smaller ones. - and higher contrast.

Dont' see the response time getting much quicker though, so if you are sensitive to 'smearing', then that might still be an issue. But I don't think its a problem, even on current top LCD TVs.
 

calscot

Standard Member
what jagged edges?

Well it depends on your deinterlacer - a poor deinterlacer will just "bob" ie double up the scan lines for the whole picture in video mode giving half the vertical resolution and therefore jaggies.

However a crt copes with the same thing by using an interlacted picture which produces a feathering/mice teeth effect and line twitter.

Both are rubbish.

The best solution by miles is a progressive screen with a decent deinterlacer which does motion adaptive, per pixel, bob and weave.
 

StooMonster

Well-known Member
Originally posted by nigel
Geometry
Except that LCDs tend to be physically (and resolution) of 16:10 ratio, whereas, DVD output and Sky etc are in 16:9 format. Therefore a circle will not be circlular.

16:9 CRTs and plasmas are physically correct ratio though and display this content correctly.

StooMonster
 

LV426

Administrator
Staff member
Some are; some aren't. Mine is 1280x720 (=16x9) and it measures right, too. And those that are 16x10 don't necessarily have to have bad geometry. Geometry can be fixed with reduced vertical overscanning and/or increased horizontal overscanning, if it matters.

In any case, the likelihood of a circle being truly round on a CRT is pretty remote.
 

richard plumb

Distinguished Member
mine is 16:10, but has a widescreen zoom mode for accurate 16:9 image with tiny bars top and bottom.

As for the jagged comment, I was just referring to my specific screen, which has an excellent deinterlacer. I see your point in general terms though.
 

RAMiAM

Novice Member
Originally posted by StooMonster
Except that LCDs tend to be physically (and resolution) of 16:10 ratio, whereas, DVD output and Sky etc are in 16:9 format. Therefore a circle will not be circlular.

16:9 CRTs and plasmas are physically correct ratio though and display this content correctly.

StooMonster

To say that circles on 16:10 panels will not be circular and that only 16:9 panels display correct content is utter nonsense. I can't believe you actually wrote that :eek:
 

38H21543

Novice Member
Very helpful info from Nigel above.
I also read about where new DLP rear projection tv's may be going from this link which someone posted.
http://www.digiupdate.com/105_DLP_RPTV.html

So, what is the resolution of broadcast TV going to be in the next few years in the UK and Europe?

The article shows DLP to have 720 and then 1080 vertical pixels. LCD is following this route.

Why are plasma screens not going in this direction, and what is the point of 480 (USA NTSC), 768 (PC display), 1024 (?), for tv/video in the UK and Europe?

Thanks
 

LV426

Administrator
Staff member
Originally posted by 38H21543
So, what is the resolution of broadcast TV going to be in the next few years in the UK and Europe?

No known plans for anything better than PAL (AFAIK) except in limited circumstances. However (peers into crystal ball) my guess is that we will begin to see DVD discs containing Hi-Def WMV files, and tabletop DVD players with the ability to replay them.

Originally posted by 38H21543
Why are plasma screens not going in this direction, and what is the point of 480 (USA NTSC), 768 (PC display), 1024 (?), for tv/video in the UK and Europe?

They are. But you have to spend more to get one. It is only the cheapo models and some brand names that are fleecing the public that are sticking with low resolution. And the reason they are <>x480 is because they don't make different panels for use in PAL countries - we have the same panels that are used in (and designed for) NTSC. Those that are <>x768 are panels that can also be used for PC driven content - you may see them, for example, in airports announcing departures etc. And <>x1024 is high definition. Again, in both cases, they aren't going to tool up to make special panels just for the likes of us PAL users, when they can cover the difference with a scaler.
 

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