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Colour and brightness adjustment?

Discussion in 'Desktop & Laptop Computers Forum' started by JohnS, Sep 26, 2002.

  1. JohnS

    JohnS
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    Like the title says, where do you adjust he brigtness contrast and colour when using a HTPC with a PJ?

    The PJ
    The advanced settings in the graphics card
    The settings from within the dvd playback program.
    A combination of all of the above.
    It doesn't matter.
     
  2. Mr.D

    Mr.D
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    definitely does matter.

    You need to ensure your HTPC is putting out a healthy picture ie not clipping ior crushing. A good start is the theatertek scoped settings fro various graphics cards : not so good if you ain't using theatertek though I suppose.

    What I'd suggest you do is set your overlay settings in the software based on hooking up to a CRT monitor. The larger intensity scale of CRT makes the set-up a little more transparent verses a digital panel with far less intensity response. ( inaccuracy in the black and the whitepoint setting on the CRT is thus far less likely to crush the intensity range as you have so much more range to play with compared with an LCD/DLP etc.)

    Once you are happy with your picture on the CRT transfer to your digital pj and calibrate the projector settings leaving the HTPC ones alone. Additionally some ( not all) digital projectors apply gamma correction to replicate a CRT type response curve rather than a linear LCD/DLP one. However a lot don't so once you are on the projector you most likely will have to retweak gamma on the overlay ( leave brightness and contrast alone on the HTPC though)
     
  3. JohnS

    JohnS
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    No, not yet! Power DVD 4 xp at the minute.

    So are you saying that it doesn't matter what the contrast and brightness of the actual monitor settings are, because we are just adjusting the software range?

    I take it you are reffering to the- cool - normal - warm -settings on the ae100 that I have too. What about the other - natural - normal setting? Then to tweak the gamma with the seperate R, G, B, settings.
     
  4. Mr.D

    Mr.D
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    OK I'm rendering so I have a wee bit of time.

    The black and whitepoint setting on the CRT ( brightness contrast) isn't so critical compared with setting it on the ae100 because there will be ample room to represent the video intensity range even with the whitepoint too low and the black point too high and vice versa on the CRT itself.

    However what it will show on the CRT is if your whitepoint and blackpoint on the HTPC overlay settings are incorrect as you will obviously clip and or crush the intensity range. ( basically the fact that the CRT is incorrectly set-up will not be such a hinderance to setting up the HTPC whereas it would be if you took the HTPC with non-fixed settings and the ae100 out of the box and tried to get the two working with each other from a intensity range point of view. So hopefully the CRT based set-up will get you close with regard to black point whitepoint and colour on the HTPC overlay settings at least to the point where you are not chopping off or losing anything at the HTPC itself. Then you do the projector settings ( brightness , contrast , colour).

    cool, normal, warm are the colour temp settings on the projector I found warm closest to 6500K but its also a personal preference to a certain extent ( I'm being generous here) . The dynamic , cinema, whatever modes seem to me to be intensity remaps: this is similar to different gammas but I'd say the settings in each case are not a simple gamma but designed non-linear curves of some description: I don't use them prefering the gamma adjustment on the HTPC overlay to control the mapping of the intensities instead: top tip I reckon the gamma on the ae100 is around 3.1 : normal CRT is 2.2 this means you need to get the gamma on the overlay down a fair bit from where it was on the CRT calibration: on my radeon VE its as low as it goes ( this deviates from the theatertek settings as these were done with reference to a CRT based display system) and I can still help it along a bit with the gamma filter in Dscaler . The gamma pattern in Avia is useful for this. This is where HTPCs come into their own with digital panel projectors I doubt many scalers offer a good gamma correction??

    I posted a fair bit in another thread(s) about calibrating an HTPC-ae100 also with the FLD filter which I feel makes an improvement.

    The seperate RGB level adjustments are for colour balance not gamma.
     
  5. JohnS

    JohnS
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    Thanks Keith,

    A lot of info their to take in so i've printed it out so I can reference to it when I'm making adjustments. I also dug up your comments from the other thread when you 1st bought your filter.

    I'd not tried the warm setting before, my initial findings are that I can now get the hue and satuatiuon set correctly on the avia colour bars (not been possible before, it had seemed to run out of range,) but when returning to watching tv, especially sky stuff, the picture seems to push the red too hard with the effect of washing out the blues and yellows. Maybe its just a radical change from what I've been used to. Seems to give colours much more punch though.

    What sceen are you using?
     
  6. Mr.D

    Mr.D
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    I'm using a lilly white over wallpaper special!

    I'll plump for a screen once the pj location is finalised ( I might also upgrade to an ae300 if its a winner).

    I like the ae100 a lot to be honest . The only negative is the screendoor: contrast range is fine for video.
     
  7. JohnS

    JohnS
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    Hi Keith,

    Yeah, I quite like the ae100 too, great value and a good chance to learn what I like and dislike about projected images and the variation from feeding different sources, but I'm projecting 8ft wide so I hanker one of the higher res projectors. Maybe the ae300 or the Sony HS10 perhaps.

    Regards
     

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