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HDTV resolution question |
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#1 |
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Posts: n/a
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HDTV resolution question
Hi people!
Im thinking of getting a HD ready lcd tv, probably a 26" Samsung or Sony Bravia. The question i have is - The highest resoultion advertised for HD at the moment is around 1300dpi, in a year or two, will newer HD television be sold with even higher resolutions say 2000 dpi or is the 1300 the "standard" for HD and it will stay at that? My laptop is on 1900dpi! Cheers
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#2 |
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Forum Member
Join Date: Dec 2004
Location: Finchingfield, Essex
Posts: 5,511
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The problem for TVs is the bandwidth of the media that supplies the pictures. To get even a 1080 line high picture to your TV at 25 frames a second requires about 20Mb/s even with MPEG4 compression. Sky have satellite bandwidth for this, Telewest have cable bandwidth for it. Sadly Freeview (DVB-T) is unlikely to ever have the bandwidth. And of course Blu Ray and HD-DVD discs have plenty of bandwidth.
But the bottom line is that unless something much cleverer than MPEG4 comes along you can't really receive more than about 1080 lines of detail. Now these sets are all 16:9 aspect ratio so 1080 high equates to 1920 pixels wide. Now your average TV these days is what? 32" diagonal. Call that 26" across aby 19" high. So your 1080 lines pack into 19" which gives you about 57 dots per inch (OK, call it 60dpi). As the source material is unlikely to ever grow beyond 1920x1080 then there'd be little point pack more dots into the panel. They could, I guess go to 120dpi an pack 3840x2160 dots onto that same 32" panel. But what's the point? It then means that each source pixel lights a group of four output pixels. But this doesn't enhance the picture any more. So the limit is set by the delivery bandwidth Cliff PS I think it EXTREMELY unlikely that your laptop has 1900 dots per inch. Assuming it was (say) 1280x800 resolution this would mean the screen was about the size of a postage stamp! (on its side) Last edited by CJL : 24-11-2006 at 17:07. |
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#3 |
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Posts: n/a
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Hi thanks for the reply, so your basically saying that a 1300 resoulution HD is pretty much here to stay?
My laptop is set to 1920 x 1200 resolution (sorry if i called it dpi by mistake)! Thanks again |
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#4 |
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Forum Member
Join Date: Jun 2003
Location: Portsmouth (Rowridge TX)
Posts: 7,052
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The lowest "proper" form of high-definition is a TV with the minimum vertical resolution of 720 lines.
The majority of HD ready TVs are 1366x768 which as you can tell, is good enough to receive the minimum high-definition standard. You could go for a 1080 vertical lined HDTV, these are a lot more expensive than 720 lined sets, and if you are watching a 1080i broadcast (1080 vertical lines scanned interlaced) the difference is negotiable between 720p (720 vertical lines scanned progressively) when viewed from a normal viewing distance. However, a 1080p picture (where the 1080 vertical lines are scanned progressively) will give you the highest quality picture possible today on a home TV. But... A 720p picture on a 26" LCD will look basically the same as a 1080p on a 42"+ TV at a normal viewing distance (plus it depends how good your eyesight is, too)
Last edited by x-p-d : 27-11-2006 at 08:10. |
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