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How do 1024 x 768 displays work ? |
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#1 |
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Forum Member
Join Date: Jul 2002
Location: Milton Keynes
Posts: 23
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How do 1024 x 768 displays work ?
Hi,
SOrry to be dumb, but can anyone explain to me how a 1024 x 768 plasma screen (which effectively has a 4:3 ratio of pixels) such as the TH42PV500 display a 16:9 picture. Surely a 720p picture is 1280*720 so does this mean that you lose resolution on the sides. And if this the case would I be better gettign a LCD panel with the full resolution ? Anyone able to shed some light ? Thanks Robert |
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#2 |
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Join Date: Aug 2005
Location: Livingston
Posts: 2,613
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The LCD wafer is distored with pixels being rectangular rather than horizontal.
On analogue outputs like composite or RGB the output is in lines rather than Pixels so it actually works OK (albiet the horizontal resolution is slightly poorer). Of course if you use a true digital connection like HDMI the picture will be degraded to a more noticable degree. I would not reccomend it for HD viewing. |
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#3 |
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Forum Member
Join Date: Nov 2000
Location: Manchester
Posts: 925
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I WOULD recommned it...There's more to a decent picture than just pixel count.
I have a plasma Pan 42PV500 and 720p and 1080i material via HDMI looks awesome. Don't worry too much about 1080 this and 1080 that. Just sit back and enjoy the HD will look MUCH better than SD. Good job nobody gets too concerned about the very high resolutions of their 'megapixel' digital cameras and the MUCH reduced res they view their photos on their PC monitors/TV screens! |
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#4 |
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Join Date: Sep 2002
Location: Scotland
Posts: 10,720
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Quote:
Originally Posted by Kevo
There's more to a decent picture than just pixel count.
Same with TVs - there's the quality of the scaler, the 'image enhancement' and various other factors. Golden rule is see before you buy. |
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#5 |
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Forum Member
Join Date: Dec 2004
Posts: 3
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Sorry, but I don't understand this.
If you've got a source video stream with 720 rows for a 16x9 display you should have 1280 columns of pixels. If you only have 1080 on your display you are loosing 1 in 5 of your pixels ie for every 5 pixels in the source stream it can display only 4 - this must be a degradation which will loose fine detail eg hair. Hence it is not full HD. And then there are the screens that claim to be 1020 but only have 1024 columns - they would hence loose 960 / 1980 = about half the pixels horizontally. Don't tell me you wouldn't notice that. Also if you have a screen with 768 rows how does it display 720 data - does it skip the top 24 / bottom 24 or does it add the odd line in the middle? And final question - has anyone seen *any* 42 inch plasma displays that are 720 x 1280 and if not why not? (its very hard to check as the magazine reviews seem very relaxed about checking their facts for horizontal resolution - they only concentrate on vertical) There seems to be no shortage of 720x1280 or 756x1336 LCDs though the ones I've seen don't do SD that well (and for the near future that is critical) Its all very puzzling. |
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#6 |
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Join Date: Nov 2003
Posts: 1,770
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To answer your last question first, it's very difficult to shrink the feature size of plasma to produce a high resolution panel, and this is why you see 37" and 42" panels with resolutions like 1024 x 720p, 1024 x 768p, 1024 x 1024i and 1024 x 1080i, all with a 16:9 aspect ratio. Only 50" panels can fully resolve 720p (the Pioneer PDP5000EX is the first 50" plasma to be 1920 x 1080p native).
Most HDTVs simulate CRT overscan by zooming in the image slightly to hide unwanted control signals that can sometimes be seen at the edge of a TV picture. So it's quite likely that 720p will be cropped slightly before being stretched to 768p. Scaling works in fractions, not by repeating or skipping lines on a proportional basis. When downconverting 16:9 anamorphic to 4:3 letterbox for example you effectively need to squeeze four lines into three. The scaling algorithm may work something like this: Line 1 = 0.75 x line 1 + 0.25 x line 2 Line 2 = 0.5 x line 2 + 0.5 x line 3 Line 3 = 0.25 x line 3 + 0.75 x line 4 ...and so on. When buying an HDTV my first preference would be a plasma with 1280 x 720p resolution or better (which at the moment would mean buying a 50" screen). My second preference would be a plasma with 1024 x 720p or 1024 x 768p resolution, and I would choose that over an LCD with 1366 x 768p or even 1920 x 1080p resolution. Why? Because the more realistic colour palette, contrast and black levels of plasma make for a more lifelike picture in my opinion, despite the lower resolution levels. I have compared the same 1080i HD material side by side on a 1024 x 768p plasma and 1920 x 1080p LCD and I felt that the plasma managed to resolve more detail than the LCD. There's no denying that the lower resolution of plasma is a compromise, but until the picture quality problems of LCD are sorted out (hopefully by the introduction of LED backlighting) plasma is the best choice for picture quality. Last edited by meltcity : 27-09-2006 at 23:43. |
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