Line Doublers and Projectors

Discussion in 'Displays' started by Paul Newton, Jan 13, 2004.

  1. Paul Newton

    Paul Newton Auditioning

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    Hi Guys


    I was wondering if any one out there is running a line doubler on their projector??


    I have a Proxima DP9250+ which I got from the US a few years ago and I was thinking of getting a line doubler for it.

    I have been looking at a few but most say you need a display that is capable of Progressive Scan which my projector is not so I wondered if I was to get one would it make any difference at all with my Video Quality..


    My projector is LCD XGA 1024x768 Native 2000 Ansi Lumens, it only has S-Video and Composite inputs on it, it would have been nice if it had component inputs or DVI but it is a little old for that..



    Look forward to your replies!!


    Cheers!
     
  2. Craig Robertson

    Craig Robertson Supporting Actor

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    line doublers convert the interlaced image that you have into a progressive scan image, effectively doubling the number of lines being scanned at one time. that's why you need a progressive scan capable display.
    unfortunately, in your case it would do nothing for you.
     
  3. Paul Newton

    Paul Newton Auditioning

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    Craig

    Thanks for your reply!!


    I actually thought the same thing that is why I posted the thread just to be sure but I have also asked the same question on the AVS forum and a couple of replies have been that as the unit can accept a computer VGA input of 640x480
    then it is possible to put a line doubler on it, something like iScan Pro for instance.

    So now I am a little confused as to weahther a line doubler will work or not..


    Reagrds,


    Paul
     
  4. Dale Adams

    Dale Adams Extra

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    Your projector has a VGA input which is intended to accept RGBHV computer signals. If a line doubler can produce an RGBHV output (like the iScan Pro can), then it will almost certainly produce a picture on your projector.

    Whether it will be better than what you have now or not depends on a number of factors. One potential issue is that some older projectors expect to see a standard VGA computer signal (640x480) when there are 480 scan lines in the image. Most line-doubled signals are 720x480, so there may be some aspect ratio distortion with the line-doubler output. Another possible trouble area is vertical banding, which can occur when the projector only samples the line-doubled signal at 640 points instead of 720 (or more).

    Note that your projector will still be scaling the line-doubled image to its native resolution of 1024x768. An external scaler (as opposed to just a line-doubler) typically can produce this output resolution directly. Most likely, the scaling in the external scaler will be better than what your projector does, so the image will likely improve. A scaler can normally take care of any aspect ratio issues, too. Note that scalers are typically more expensive than line-doublers, however.

    The only real way to be sure if it works to your satisfaction is to try it. The DVDO website has a 30-day money-back guarantee, so it's relatively risk-free to try it if you buy directly from them.

    - Dale Adams
     
  5. Paul Newton

    Paul Newton Auditioning

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    Dale

    Unfortunately I am located in Australia so buying one from DVDO with a Money Back Guarantee is not possible..


    I was thinking of the DVDO iScan Pro actually as it is inexpensive and is not an over kill for the projector I have.

    Looking at the DVDO web site it actually lists the Proxima DP9250 saying it should work..

    Do you know of any possible checks that I can do that will assist in my decision to purchase the iscan pro??


    Regards,


    Paul
     
  6. Paul Newton

    Paul Newton Auditioning

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    Just looking at the specs on the proxima web site for the DP9250+

    Fit-to-View support of VGA (640 x 480) to SXGA (1280x1024) resolution means worry-free compatibility

    800 TV lines of horizontal resolution with digital scaling offers superior video image quality


    800 TV Lines meaning it must have its own bit in scaler so would I be correct in saying that somthing like an iscan pro could only be better than an in-built scaler on the projector??
     
  7. Dale Adams

    Dale Adams Extra

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    When the DVDO website says that a display "should" be compatible, it means that the published specs for the projector indicate that it should work, but that there's no hard data or direct empirical evidence available that says that it actually does work without any problems. If you have a PC that you can set up to produce a 720x480 output resolution, then you could run that into your projector and see how it responds.

    - Dale Adams
     
  8. Paul Newton

    Paul Newton Auditioning

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    Sorry Dale I am probably getting into the really lame questions here but I was not aware of a PC that could run that resolution. Is a special Video Card require or software perhaps??
     
  9. Ian-Fl

    Ian-Fl Second Unit

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    My projector has a VGA input I use an adapter similar to this
    http://store.infocus.com/escalate/st...2b6b:&tab=desc
    From my progressive scan player, I've run my three component cables into the adapter and plug it into the projector. The picture is 50% better than the s-video input on my projector. Try that first and see if you get a better picture.
     
  10. Paul Newton

    Paul Newton Auditioning

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    Ian, Is your Projector an X1??

    It actualy says it is for the X1, but I don't see any reason it wouldn't work on others!!

    Is your Projector capable of Progressive Scan??


    Regards,

    Paul
     
  11. Ian-Fl

    Ian-Fl Second Unit

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    My projector is a NEC vt45. I have the adapter from NEC. It's the same thing as in the link. I don't see any differance.
    My projector is two years old and has a VGA in, a s-video in, and a RCA in. The VGA works the best with a progressive scan player with component outs.
    You can even build one if you like.
    http://www.myhometheater.homestead.com/vgacable.html
     

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