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Colour Space Problem ?

Discussion in 'LCD & LED LCD TVs' started by paulfoley, Mar 7, 2005.

  1. paulfoley

    paulfoley
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    Connected my HTPC to my new Samsung LCDTV (730MW) via the DVI Socket & the picture was very good. I then ran the THX Optimiser (free on most Pixar DVD's) to set the correct contrast, colour, etc. Problem was that I wasnt seeing the full range of shades for white & Blacks. I understand that this is a Colour Space Problem ?

    Would this be caused by the Screen, by the included Samsung Driver or maybe my Graphics Card (Radeon 9800 Pro) ?

    Any ideas how to resolve it ?

    :smashin:
     
  2. richjthorpe

    richjthorpe
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    Not sure about PC's but some DVD players are incapable of showing blacker than blacks and you only get 7 black blocks on the test screen instead of the 9 or 10 you would see. Not heard about not getting the whites though.

    Richie.
     
  3. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Nothing to do with colourspace I think.. More likely your PC is sticking out PC digital video levels rather than VIDEO level digital signals. I'm not an HTPC geek so cant tell you whether it's hardware or driver fixeable. Suggest you post on HTPC forum.

    Gordon
     
  4. paulfoley

    paulfoley
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    I think you are right Gordon. Updated the ATI Graphic Card drivers and now we have the four shades of white instead of a single block of colour. Still got the missing THX Shadow & a few shades of black missing ?

    I need the HCPC Experts methinks - Mods please can you move this thread into the PC Section ?

    :smashin:
     
  5. mike7

    mike7
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    On the subject of Graphics Cards what do members recommend as an appropriate one (with DVI) output which is usable with LCD tv's ?
     
  6. jon2099

    jon2099
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    Actually this is caused by the panel itself. The 730MW uses a 6-bit panel, which means each subpixel only has 64 shades, as opposed to more expensive 8-bit panels that have the full 256 shades. 6-bit panels are normally coupled with FRC (Frame Rate Control), a form of dithering in time to increase the number of shades to 253.

    This brings the number of colours that can be rendered up to 16.2 million (2^253); proper 8-bit panels can render the full 16.77 million colous (2^256). How effective the FRC is depends on the manufacturer but suffice to say you won't be able to display the full gamut of colours without some banding. I believe the panel used is the LTM170W1:

    http://www.samsung.com/Products/TFTLCD/LCD_TV/LTM170W1/LTM170W1.htm

    6-bit panels are quite common at this size and is common at the budget end. AFAIK, the Toshiba 17WL46 and the Philips 17PF9946 use 8-bit S-IPS panels (and possibly the LG and JVC 17" as well).

    As for graphics cards, it seems the ATI Radeon series have a better implementation of DVI as in the signal is more within specification especially at extremely high resolutions.
     
  7. paulfoley

    paulfoley
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    Thanks for the detailed answer John. I'm still happy with the picture as it is. At least now I can stop wasting my time trying to resolve it.

    :smashin:
     
  8. jon2099

    jon2099
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    Great :) Apparently Samsung have one of the better implementations of FRC out there. I have the 172X monitor, which also has a 6-bit panel, and I regularly watch recorded broadcast TV content on it (recorded using a USB DVB-T box on a PC) as well as the odd movie and I'm very happy with the picture.
     
  9. paulfoley

    paulfoley
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    Changed my DVD Playback Software to Power DVD 6 & I now get all of the shades of white & black plus the shadow on the THX Logo - Hooray !

    :clap:
     

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