Red Push Question.

Discussion in 'Archived Threads 2001-2004' started by Ryan Pream, Jul 9, 2001.

  1. Ryan Pream

    Ryan Pream Stunt Coordinator

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    Can someone give me a detailed explanation of what Red Push is? In particular, why setting the gray scale will not fix Red Push.
    Thanks,
    Ryan
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  2. ThomasL

    ThomasL Supporting Actor

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    Ryan, red push and grayscale are two entirely different animals. In a nutshell, grayscale tells your tv how to render black and white images of varying intensity. Since the tv's phosphor screen is made up of 3 phosphors - blue, red, green, that are all fired at with electrons, the tv somehow needs to know how to make something a shade of gray - i.e. what mix of red, green, and blue will give it the neutral gray it needs to display. Red push is simply an overemphasis of the red signal by the tv's color decoder. It simpy means reds on the screen will be more intense in relation to other colors (sunburned faces, etc.). Changing the grayscale may affect how your eyes perceive oversaturation of red (i.e. red push) but you're doing it at the expense of changing the way gray looks and drastically if you change the CUT and DRVs a lot. The easiest way to determine if you suffer from red push or an overly red tinted grayscale is to get the Avia DVD and bring up the color decoder test pattern. This one will tell you if you're suffering from red push. Then bring up the Avia 10 step grayscale pattern and look for a color tint to the grayscale. While it may not be D6500, your eyes will be able to tell if its too red, too green, or too blue. I'v found this to be the quickest way to determine if it's a red tinted grayscale problem or a red push problem.
    hope this helps,
    --tom
     
  3. Ryan Pream

    Ryan Pream Stunt Coordinator

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    Thanks that helps a lot.
    Ryan
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  4. John Morton

    John Morton Stunt Coordinator

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    ThomasL......
    Thanks for the post. I'm fairly new to tv calibration. I've had great success with me Wega, but have however been having a heck of a time with a friend's set. Are you saying that the cut and drv settings should be used to adjust the grey scale and not the saturations of individual colors? Don't they go hand in hand?
    Thanks again!!
    John
     
  5. GlennH

    GlennH Cinematographer

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    Red Push is such a problem on Mitsubishi RPTVs that owners have taken things into their own hands and built "red push attenuators" with parts from Radio Shack.
    This post in another forum contains an excellent explanation of the phenomenon including pictures.
    (I don't know if I should link to other forums directly here, but that really is the best explanation I've seen on the subject.)
     
  6. TrevorB

    TrevorB Auditioning

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  7. ThomasL

    ThomasL Supporting Actor

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    John, take a look at this article by Guy Kuo regarding color decoder vs. grayscale.
    http://www.keohi.com/keohihdtv/usefu...ordecoder.html
    Essentially if you change the service level grayscale variables - e.g. CUTs and DRVs - in order to fix an oversaturation of red in the color decoder, then you'll be altering the color of gray (from white to black). While it may seem like you've alleviated the red push at first glance, what you've done is removed a lot of red from the grayscale and thus your grays will most likely look some shade of blue/green. This is why I think it is important to determine where/what is causing the perceived oversaturation (the color decoder vs. grayscale) and then make adjustments accordingly. As the above article mentions, the color decoder pattern in Avia allows one to set the overall color saturation and/or change the color decoder variables independent of what the grayscale looks like. Thus I would set the color saturation first and then go in and use the Avia grayscale patterns to check the grayscale.
    hope this helps,
    --tom
     
  8. John Morton

    John Morton Stunt Coordinator

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    Thanks guys!!! I'll definitely read those recommendations.
    I have SO much more to learn!!! :)
     

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