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Projector jargon....

Discussion in 'Projectors, Screens & Video Processors' started by Family Guy, May 26, 2003.

  1. Family Guy

    Family Guy
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    New to this PJ lark. I have carried out a search of the forums for some help but get about 400 threads to trawl through...:eek:
    Looking to learn some of the lingo :smoke: but at the same time, find out what it means...
    I'll start with SCREENDOOR - what is it and how does it affect my viewing...?
    Over to you professor:lesson:
     
  2. theritz

    theritz
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    Well, not so sure about this.....


    but screendoor is the term used for the "grid" appearance of the gap between the pixels you can see when an image is projected from an LCD projector... the term comes from the screendoors used in the USA to keep out mosquitos and other bugs.

    It's a factor of the resolution of the projector and the size of image used..... an 800x600 PJ throwing a 7' image, for instance will give lots of screendoor (particularly as its a 4:3 panel where a fair amount of the panel will not be used when displaying a 16:9 image...... not up to doing the math at this time of night), whereas a HS10 (1368x768, native 16:9 panel) will give practically none.

    The type of panel used is also relevant, as the "fill factor" (the ratio of pixel size compared to the size of the gaps between them, broadly speaking) differs between model and manufacturer.



    The appearance of screendoor can be very much reduced by sitting 1.5 - 2 times the screen width from the screen, a little de-focus can also help, though it drives some people nuts, hence all the guff about it.

    All the best,

    Sean G.
     
  3. Family Guy

    Family Guy
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    So now I know....what's "Raster"?:confused:

    And I thought I would move this from the Progresive Scan section to here as well...

    Having never ventured into these here parts of the forums for 2 odd years, I come cap in hand to improve my knowledge of all things Progresive...
    What is PS and how does it improve picture quality? What's the difference between NTSC and Pal PS? And more importantly, will a PJ that outputs NTSC PS output pal progresive...? (I'm hoping the answer on this one will be yes...)
    I have managed to secure a Sony HS1 for a 1st PJ - collecting first week in July. I have gone as far as changing my DVD player to a Cambrifge audio DV57 for the Pal and NTSC PS output...have I wasted my money?
    For the record, the HS1 outputs 480 & 720p - whatever that means...

    I'm sure all the experts in this section will be able to help me out...go gently and speak slowly. A phd I certainly don't have...
     
  4. theritz

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    AAaaaargh, you're making ny head hurt...... Some judicious searching/surfing on the forum here, in progressive and in DVD players would answer your questions a lot easier, but you might make do with this for now..........

    Nothing to do with LCD PJs.... its the scanning area on a CRT projector..... more or less (Gordon F. will correct if not.....)


    Progressive scan (PS) means that the frames in a movie are shown as complete frames one after the other - on a normal telly they are interlaced - the frames are changed by changing the odd numbered lines first, followed by the even numbered lines. PS gives a smoother picture. All LCD projectors display images in progressive scan mode - that's the way they work, so an LCD projector de-interlaces ( disassembles the frames and puts them back together as full frames) and scales ( re-sizes the image to fit the size of the LCD panel) the image.


    Prog Scan dvd players have been available in the US for quite a while. Only recently has the DVD Forum (International body for agreeing dvd standards and licensing) agreed that mfacturers can include prog scan technology in PAL DVD players, tho' some manufacturers were already producing them.

    The difference between the two in technical terms boils down to the way that the frames are re-assembled when they are de-interlaced ( do a search for 3:2 and 2:2 pulldown in prog scan forum or on Google, I understand how it works but am unlikely to get the explanation exactly right without digging out stuff myself)

    You mean will a projector that accepts a NTSC prog scan signal also accept a PAL prog scan signal.... I think ? ...... it should do.... If the projector's specs say that it accepts 480p, that's NTSC prog scan (the 480 is the number of horizontal resolution lines, the "p" means progressive, if it were "i" it would mean interlaced). PAL PS is "576p".



    The main reason that people go for a dvd player that will do prog scan is because the dvd player will quite often have better de-interlacing ability than the projector - if the projector is fed a prog scan signal, then it doesn't have to do the de-interlacing itself, it just scales the signal to fit the panel. (Some newer models have very up-to-date de-interlacing from Silicon Imaging, or Faroudja, but these tend to be at the upper end of the market).

    Check the DVD players forum for opinions about the dvd player mentioned, I use a computer to play dvds (does de-interlacing and scales the image to a perfect match with the panel size, then sends signal to PJ, called 1:1 pixel matching) so I ain't too hot on dvd players.

    All the best,

    Sean G.
     
  5. Family Guy

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    Top man - thanks very much - though from what you are saying, my PJ might not do Pal progressive - defo does 480p and I believe it does 1080p as well (Hi Def?) but no mention of 576p in the specs though...

    I've done a couple of searches through google and printed of a few reames of info (I'm at work so free!!) so I'll get my head around that for the rest of the night.

    You are a top man...:smashin:
     

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