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The Current Range Of Dlp's Not True Hi-def??

Discussion in 'Televisions' started by soni, Nov 18, 2004.

  1. soni

    soni
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    Can somebody enlighten me. I will be purchasing one of the RP DLP sets within the next few weeks, however i have been told that they are not true hi def. Is this correct? If so, are there any sets available that are true hi def? If there are not, will i be wasting my money on the current hi-def dlp sets available if they are not true hi def?
     
  2. Dutch

    Dutch
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    Hi,

    All the current DLP RPTVs use the 1280x720 resolution DMD so they are perfect for 720p HD signals. Other HD resolutions such as 1080i would be deinterlaced and scaled to fit the 1280x720 panel. Hope this helps.

    Steve
     
  3. soni

    soni
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    Don't mean to appear thick, but find the HD resolution thing a bit difficult to get my head around as i don't really understand what the numbers mean.

    You say the current sets are 1280 x 720, so it'll be fine for 720P (what does the 'p' stand for).
    But the 1080i (what does the 'i' stand for) you said it would be scaled to fit, does that mean loss in quality? Also, what do you reckon they will broadcast, 720 or 1080? Or a mixture of the two? When you talk about 1280 x 720 is it the 720 bit that matters as you said the 1080I would be scaled to fit.
     
  4. Dutch

    Dutch
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    Hi,

    "i" = interlaced = bad
    "p" = progressive = good ;)

    720p refers to a signal of 1280 x 720 pixels shown 50 or 60 times a second depending on the broadcast standard.

    1080i refers to a signal of 1920 x 1080 pixels shown 50 or 60 times a second, but only 540 of those 1080 scan lines are shown in each field (2 fields make up one frame). Therefore this is only really equivalent to 25 or 30 frames per second.

    I think Sky will use 720p 50Hz (their US owners use 720p 60Hz), so I think it's a fair guess they will also go with 720p. A 1080i signal would be deinterlaced (to 1080p) then scaled down to the 1280x720 size required by the set's DMD. Hope this explains it better.

    Steve
     
  5. beeblebrox12

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    To put in the simplest possible way - 1280x720 DLP TVs are probably the best currently available HDTV sets on the market. They are just as "true" HDTV as the rear projection 1080i sets, even better in sharpness and detail.
     
  6. soni

    soni
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    Thanks Dutch & Beeblebrox12 for clarifying!

    Im going to the Ashford Comet tommorrow morning to check out the new Tosh. I'm taking my DVD player along with me so i can get a true look at what i will be watching at home as opposed to the Hi-Def signal that it will probably be displaying.

    Thanks again lads
     
  7. loadsofleads

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    I've going to wait for the 1920/1080p Dlp's to come out that should make an apperance in 12 months or so, then hook it up to a Blu-Ray recorder and a Sky MPEG 4 HD Digibox, ohhhh NURSE :zonked:

    loadsofleads :thumbsup:
     
  8. whiteswan

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    I have just bought the Tosh dlp hi def tv.

    In the instruction book it says to connect 1080 signals into the component sockets for hdtv - so i assume this tv will take 720 and 1080.

    Dave, Oldham.
     
  9. hornydragon

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    there are a few select 1920x1080 displays available...... there is a 4000x3000 res PJ available for those of you with a thick wallet.....£2million + but most diplays will display both 720p and 1080i signals with a bit of scaling one way or the other...
     
  10. Stephen Neal

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    To be completely accurate :

    720p normally implies 1280x720 sampling with every line of every frame sent every time. So 720/50p will mean 50 complete 1280x720 frames are sent a second.

    1080i normally implies 1920x1080 sampling (though 1440x1080 is also used) with every OTHER line of each frame sent every time. So 1080/50i will mean 50 1920x540 FIELDS are sent every 50th of a second. Thus it takes 2 fields to deliver 1 frames worth of vertical detail - but objects can move between the 2 fields, so the motion information is still carried at 50 times a second. (A common mistake is to assume that the frame made up of 2 fields contains the same image information - it doesn't have to, the frame can be refreshed between fields, allowing for field-rate motion rendition, and frame-rate resolution on static or slow moving objects)

    1080p normally implies 1920x1080 sampling and every frame sent every time, so 1080/25p implies 25 complete 1920x1080 frames sent every second (so far less motion information than 1080/50i or 720/50p)

    Most HD DLP displays on sale are 1280x720 resolution - and they are inherently progressive. They can display 720p stuff native, but any 1080i stuff will be converted to 1080p progressive and then scaled down. This is not quite as bad as it sounds as a 1080i signal doesn't have the full 1080 line vertical resolution - it actually has only around 800 lines of effective resolution, so the resolution loss is not great. However interlace to progressive conversion and scaling both mean a process where quality can be lost.

    There are now plasmas and LCDs with 1920x1080 native resolution. They are still progressive - inherently - so will require a 1080i feed to be de-interlaced to 1080p, or a 720p feed to be scaled to 1080p.

    The only displays that display 1080i interlaced natively are CRTs (either 3 tube projectors or direct-view TVs - which are huge and weigh a tonne) - which is why many people hope that a progressive standard or standards will be chosen for Europe. 720/50p and 1080/25p are the likey candidates - though I suspect 1080/50i will be retained (and 1080/25p delivered via this route) as the bulk of the broadcast industry in Europe is produdcing in 1080/50i and 1080/25p - with almost no 720/50p stuff in use.

    (25p is close to the 24p used in film, so suitable for HD drama. 50p and 50i systems provide far more fluid motion as they provide double the number of picture refreshes a second, so are better for sports and entertainment shows)
     
  11. soni

    soni
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    Thanks for your reply Stephen.

    Do you know the Model/Brand of the 1080I HD CRT/Direct View sets that you refer to above, only i would like to eliminate these prior to purchasing the Tosh DLP.
     

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