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1366 x 768..Really !!

Discussion in 'LCD & LED LCD TVs' started by Jakus, Sep 25, 2005.

  1. Jakus

    Jakus
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    There has been much talk around about matching Your PC output to the LCD Panel's correct resolution
    I have a philips 37" 37PF5520D/10 with claimed 1366x768 using Powerstrip I generated some new resolution profiles using the advertised 1366x768 it was good but not perfect.. :mad:

    I have found a simple way to test, You simply make a text file and fill part of it with lots of AAAAAAAAA or WWWWW if you then move that around the panel you are able to see easily any pixel miss match (part pixels trying to turn on)
    Well Up and down was no problem....768 was correct, Horizontal I was getting very slight problems...Very Strange ! To cut a long story short setting to 1370 Horizontal pixels Has made it about perfect.. :)

    What gives I am using 1370x768 on a 1366x768 Panel and its perfect, It's on a perfect DVI to DVI Digital Feed ??
    My only thoughts are the Panel has more than 1366 horizontal lines for maybe some sort of Overscan Function ?
    Anyone with Thoughts on this I would be pleased to hear them, Thanks
     
  2. Doctor Hades

    Doctor Hades
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    Most panels have a resolution of 1366x768 but to get 100% accurate 1:1 pixel mapping you need to set the resolution to either 1360x768 or 1368x768.

    With the former you'll have a tiny 3 pixel border on either side and with the latter you'll lose a one pixel line at each side. The horizontal resolution must be a multiple of 8 hence 1360 or 1368. 1366 is not a multiple and therefore will not give you 1:1 pixel mapping as you've found out. Nor will 1370 for that matter...
     
  3. Jakus

    Jakus
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    You are the Man Doc H ! Thank You
    I was not far from attempting to count the Horizontal pixels
    A slight Issue If I may ?
    My guess is some sort of scaling effect is in play as if it were not it would just be mapping selected pixels and not trying to turn on part pixels causing the slight bluring of text Your thoughts ?
    All of the Horizontal resolutions look good, I just thought 1370 looked Slightly better !
    I went down untill degredation, then up 50% of the difference was 1370.
    Ahh a thought, Native !! shrinks the display to I/2 width ?? Zoom (opposite of native gives Full Screen I have tried some High resolution inputs which go out of range for the PC input , Switching the TV to HD it then accepts the inputs.
    My conclusion is there is an I/O controller that sits between the DVI in and the LCD Drivers, as that same DVI Handles PC and HD signals
     
  4. Rob1698

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    A PC graphics card can only generate horizontal resolutions that are a multiple of 8.
    So when you set 1366 it will actually use 1360 or 1368.
    Apparently your program uses 1360. When you set 1370 it uses 1368.
    The TV may be scaling 1360 to 1366 and chopping off 1368 to 1366.

    I don't know the design of the 37PF5520D. I have a 32PF9986 and its schematics show that it converts the digital input from DVI into analog RGB, then converts that analog signal back to digital. The analog step inbetween acts as the pixel interpolation when you input incorrect resolutions (indeed resulting in visible effects on character fonts).
    When there are slight errors in the clock frequencies used, it could even be that a "different" resolution on the PC actually maps better.
     
  5. Jakus

    Jakus
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    Thanks Rob
    Sounds spot on to me !
    Shame in a way they don't have a specific Direct Digital for a Digital pc input, they make a perfect very large monitor.
    It is Obvious when You think about it that the fluidity offered by the D/A/D
    is required for proberly 95% of the Users the Tv's will be sold to

    I must say How well It works Also...without sitting on top of it looking at 5mm high PC generated text you would never Know It was not 100% perfect
     
  6. Rob1698

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    Yes, at first I was amazed (disappointed) as well when I saw this, but then I tried sending a normal analog VGA signal to it and there is absolutely no visible imperfection.
    As long as it is not visible, who cares that there is an analog step between?

    However, the newer 32PF9830 (this year's successor of the 9986) is claimed to have solved this. It may be that your TV is a newer design as well.
    The only way to know for sure is looking at the schematics. With my 9986 they are on the CD-ROM that is packed with the TV.
     
  7. Jakus

    Jakus
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    When I get back Home tomorrow i'll see if I can find some schematics and let you know, Although I do not recall getting any CD with the TV there was quite a bit of paperwork
     
  8. Jakus

    Jakus
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    Hi Rob
    I have found the schematics (in with some of the supplied Paperwork) Yes it looks Like all things lead Straight to the Scaler ! But as You said Who cares as it does it so Perfectly without any Noise Fuss or distortion, Hey I might try an analogue PC Input to see if It does it as well as the DVI which is as Perfect as I would have thought Possible with my custom 1370 setting .
     

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