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Setting Color/Tint using Red Filter

Discussion in 'Archived Threads 2001-2004' started by WarnerL, Nov 3, 2001.

  1. WarnerL

    WarnerL Agent

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    Hi All,
    Just wondering. Since it seems that a lot of TVs have over-emphasized reds (Red Push) to some degree and that it is more noticeable to us viewers especially with skin tones, why do we set up the color/tint with the blue filter rather then a red filter. I know that the proper color patches in the SMTE bars to set up the color/tint using a red filter are not in ideal positions although I believe I have read that the AVIA Calibration DVD has test patterns that put the corresponding red color patches together so one can use the red filter and set up the color/tint relative to the red levels. I have the Video Essentials DVD and all it says to help with red push is to turn down the color (saturation) until the red comes under control and this obviously turns down the levels of the green and blue. So you people that have the AVIA DVD and the red filter, what do the colors look like if you set the color/tint controls using the red color as your reference color. I assume that on a TV with some red push, that your greens and blues would actually be under adjusted but isn't that what happens when you just turn down the saturation control like the Video Essentials DVD says.
    I don't have the AVIA disc but I can generate the proper color patches using Photoshop and then can burn them to a CD-RW as a SVCD/VCD which my DVD player can play. I don't have a red filter though. I understand that a suitable red filter can be bought at a camera store. What specifications for the red filter would I be looking for as I understand that there are numerous photography red filters available but obviously only one certain shade would be correct for purposes of calibrating a TV?
    WarnerL
     
  2. Steve Schaffer

    Steve Schaffer Producer

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    Warner,
    I have the AVIA disc, which comes with red, green, and blue color filters, and has corresponding color bar patterns.
    I've calibrated 4 different sets with it, all of which have had 10-20% red push per the color decoder evaluation pattern.
    Using the red filter with the red color bar patterns gives me about the same color setting as matching red intensity to other colors on a standard color bar pattern.
    I have never observed any undersaturation of non-reds using this method when watching normal material--greens and blues do not looked washed out or muted.
    In my experience, grayscale is more of a factor in how regular material looks than 10-20% red push from the color decoder.
    I had one set that had a distinct greenish bias on regular material, yet had +20% red push and -15% green push.
    I haven't had any experience with a set with severe red push, however, as the Mits are reputed to have, so my experience may not apply in other circumstances.
    ------------------
    Steve S.
    I prefer not to push the subwoofers until they're properly run in.
     
  3. WarnerL

    WarnerL Agent

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    So Steve,
    You are saying you calibrated the color and tint controls on some TVs using the red filter and corresponding red color bars in the AVIA disc instead of using the more common blue filter and corresponding blue color bars. Is this correct? You also said that the picture looked good with no undersaturation of the blues and greens to your eyes. If this method works, shouldn't people with the AVIA disc then calibrate both color and tint using this red filter method so they won't run into the possible viewing of oversaturated reds? Also again, do you know which type of red filter could be bought at a photography store that would be similar to the AVIA red filter?
    WarnerL
     
  4. Guy Kuo

    Guy Kuo Supporting Actor

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    Undersaturation is usually less noticable than oversaturation, but if the display has very severe red push, completely compensating the red saturation by dropping saturation while viewing red-only yields too severe a drop in overall color. That is why I only have you partially correct red push on the Color Decoder pattern in AVIA. I don't think I would recommend using red-only calibration as that will tend to overdo the drop in saturation level.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
     
  5. WarnerL

    WarnerL Agent

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    Oh, I see. Thanks a lot for the reply Guy. By the way, I just ordered the AVIA DVD online for myself. Hopefully I'll get it within the week. I'm very impressed that you, the creator of AVIA participates in these forums and are willing to spend some time to help others out, even if they haven't purchased your DVD yet. I wonder why the creator of Video Essentials never helps out like you do?
    Warner
     
  6. Steve Schaffer

    Steve Schaffer Producer

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    Warner,
    I adjust color and tint with the standard flashing color bars and blue filter. I then use the red pattern and red filter to determine how much to turn down the color to compensate for red push, leaving tint alone, but usually fudge a tiny bit and leave color a notch or 2 higher. This is sort of the same thing Guy suggests.
    I have always felt fleshtones especially, but also all other colors look oversaturated with VE settings. AVIA was a revelation in that it explained to me why this was happening and gave me a way to correct it.
    Basically I use AVIA as a guide, but not as a bible. I get as close to the exact settings called for, then pop in some regular movie that has minimal cinematic trickery as far as color (in other words, not The Matrix) and fudge things a little to make it look good to me.
    It's also been my experience that black level and color saturation on every dvd doesn't always look exactly right with the strict AVIA settings, even allowing for differences in cinematic intent.
    I've noticed, for example, that some discs that have the THX mini-calibration feature will look better if I use the THX settings on that individual disc than they do with my baseline AVIA settings.
    ------------------
    Steve S.
    I prefer not to push the subwoofers until they're properly run in.
    [Edited last by Steve Schaffer on November 06, 2001 at 09:49 PM]
     
  7. Lee-c

    Lee-c Second Unit

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    I noticed that on my Wega the "warm" color temperature setting is listed in the video menu
    as NTSC standard. So I assume the t.v. should be set to warm, even if one has toned down
    the overall color saturation to get rid of any over emphasis of red?
    I don't have any color filters, so I was unable to precisely adjust the colors based on
    the flashing color bars in Avia. Do the Wega's have a Blue only, red only or green only
    mode so you can use the Avia color test patterns without the need for a filter to view the
    screen through? Obviously I'd have to go into the service menu to find such a mode, if it
    exists (I've never used the service menu before, just got the set last week and did basic
    Avia adjustments). We have a 36 inch FV27.
    Thanks for any info. [​IMG]
     

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