What does a picture look like if grayscale is not correct?

Discussion in 'Archived Threads 2001-2004' started by Dan Kolacz, Jul 12, 2002.

  1. Dan Kolacz

    Dan Kolacz Stunt Coordinator

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    Hey All,

    Just curious as to what kind of picture to expect if grayscale is not set correctly on a RPTV?

    What would it look like if it is a "little off"
    What would it look like if it is "way off"

    I think there is something wrong with my set, all the colors look muted and there seems to be a blue tone over everything.

    Can this be a grayscale problem?

    I could open the TV and adjust it myself but someone told my I should not.
     
  2. Jack Briggs

    Jack Briggs Executive Producer

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    First, what kind of RPTV do you have?

    Second, what color-temperature setting have selected? On most consumer designs, the "Warm" setting conforms the closest to the D6,500 standard.

    If the set still has blue tint, then, yes, a technician with the appropriate test equipment (color analyzer) must adjust the set's grayscale as closely to 6,500K at all brightness levels.

    (FYI, the color temperature "labels" mean the opposite of what they are called--blue-ish or "cool" is actually very hot, while "Warm" is cooler.)

    But before you call the tech, see if you can make the appropriate adjustments from the user controls. (Do you have a calibration disc--i.e., AVIA or Video Essentials?)
     
  3. SteveK

    SteveK Supporting Actor

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    I have a 32" Sony Wega which I purchased earlier this year. The main thing I noticed was skin colors, which were much too reddish. Well, it turns out that the grayscale was WAY off. The CLOSEST reading was about 8900K and the reading at the lowest IRE level was off the scale. Other readings were as much as 7000K off! Not only were whites somewhat pinkish (which I had noticed), but dark gray and black looked more like purple. Thus, I had neither true black nor true white.

    After I had my set calibrated, all readings were within a few hundred degrees K of the 6500K goal. I still am absolutely delighted with the colors now, and sometimes it's hard to believe I'm watching the same TV as before. (Thanks Greg!)

    So the basic answer to your question is that you will not have accurate colors unless you have accurate grayscale. I find it shocking that sets are manufactured and shipped that don't even come close to the 6500K standard. I guess what looks good in the store is more important than accurate settings.

    Steve K.
     
  4. Dan Kolacz

    Dan Kolacz Stunt Coordinator

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    I have a Sony 61-HS20 RPTV.

    I have used te Avia disk and calibrated the TV to best I could.

    I have it set to NTSC Standard - WARM.
     
  5. Jack Briggs

    Jack Briggs Executive Producer

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  6. Dan Kolacz

    Dan Kolacz Stunt Coordinator

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    Just a curiosity...

    Not sure if all TVs are like this, but my TV has FOCUS and SCREEN controls on the focus block.

    I was told the SCREEN controls for R,G, & B are for controlling the grayscale.

    If this is the case, how does an ISF tech adjust the grayscale to 6500K for different brightness (IRE???) levels if there are only 3 pots for adjusting?

    Thanks
     
  7. Jeff J

    Jeff J Extra

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    Patti,
    I am definitely not expert on this, but usually most white balance controls include separate brightness and contrast settings (sometimes labeled bias and gain).
    The brightness controls are used to set white balance at low IRE levels & the contrast controls are used at the high end.
    This post is specifically related to a front projector, but I think that it gives a pretty decent explanation of how white balance controls work.
    good luck,
    -jeff
     
  8. David Abrams

    David Abrams Stunt Coordinator

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    Patti,

    The Screen Adjustments on the focus block that you are inquiring about control the amount/intensity of the electrons going through what is called grid 2 of the CRT. Never touch these, especially on newer sets. In the old days of calibration, on sets that didn't have the proper adjustments, this was the only way to help the grayscale and it did help. But with today's newer technology there are circuits that try to help with wear on the CRTs on in doing so feed off the Screen settings to maintain the same picture.

    To set the grayscale on your set you need to access the service menu which will allow for many adjustments to be made to the brightness and contrast of each individual tube. There are also many other adjustments in the service mode that will help you to achieve a more accurate picture.

    Good Luck,

    David Abrams
    ISF Calibrationist
     

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