White Gamma Gain fixes Red Push?

Discussion in 'Archived Threads 2001-2004' started by James Zos, Jul 1, 2002.

  1. James Zos

    James Zos Supporting Actor

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    After finding little success trying to battle the infamous red push problem my tweaking color decoder settings (R-Y Demodulation Angle, and R-Y Demodulation Gain) in my service menu, I tried lowering the value for White Gamma Gain and instantly saw a big improvement. At least, I THINK I see a big improvement. No more radiation burn-style faces anymore, flesh tones look a lot more natural now. I do think there might be some trade off in the overall intensity of colors though.
    My question is: Am I screwing something ELSE up by lowering White Gamma Gain to decrease red push? What is the trade off I might be making without being aware of it?
    (By the way, my understanding is that White Gamma Gain falls under color decoding, NOT grayscale. Hope I'm not wrong ... )
     
  2. James Zos

    James Zos Supporting Actor

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    No one here knows anything about White Gamma Gain?
     
  3. James Zos

    James Zos Supporting Actor

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    Bump.
     
  4. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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    What set do you own?

    By changing the white gamma level you are essentially (sort of) turning down the color control.

    Color decoder adjustments are pretty straight forward once you get the hang of it.

    Regards

    Gregg
     
  5. James Zos

    James Zos Supporting Actor

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    Thanks for responding, Gregg!

    I own a 27-inch Panasonic CT-27SF11S, manufactured in 1995.

    I just looked at the AVIA color decoder check, and according to it, my red levels are dead on at zero, but green is under by about 10/15 percent and blue is way down to -25 percent. So maybe white gamma level isn't the way to go, as you response seems to suggest.
    Since I managed to get an actual administrator to respond to this thread, can I ask you some advice?

    The settings I am working with, and that I presume are what I need to tweak to fix red push, are listed in my service menu as:

    1) R-Y Demodulation Angle
    2) R-Y Demodulation Gain,
    3) G-Y Ratio SW

    I've tried raising and lowering it and I can't tell what R-Y Demodulation Angle actually DOES, therefore I'm not sure what to do with it. R-Y Demodulation Gain seems to clearly change tint from red to green in varying degrees. G-Y Ratio SW offers four settings, one reddish, one greenish, two in-between.

    In what order do I approach these three options, and what should I do with them, to try to fix red push?

    ANY advice would be most appreciated!
     
  6. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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    Use the Avia flashing color bars.

    First select blue. Use color and tint controls to get this nailed.

    Then select Avia red. Use the R / y angle gain etc to nail this.

    Then use Avia Green. ...

    You will have to do the above sequence 3-4 times to get this nailed.

    Best of luck,

    Gregg
     
  7. James Zos

    James Zos Supporting Actor

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    Thanks Gregg!!!
     

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