Quick Grayscale Question

Discussion in 'Archived Threads 2001-2004' started by Qui-Gon John, Jan 27, 2003.

  1. Qui-Gon John

    Qui-Gon John Producer

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    When I first got my Pioneer SD-582-HD I tweaked it in the service mode because I had grayscale problems, a slight purple hue on low IRE blacks and grays. For the past 2+ years it's been pretty good and I almost never noticed this. I still don't notice it on DVD's, (except on The Good Girl the blacks had a strong bluish hue, but I understand this was a problem with that particular DVD). But recently, on a couple of cable channels I have noticed the old purplish hue again to a slight extent, like TNT I watched Crossfire Trail recently and there was a bit of this. Can the source have an effect on the grayscale? Also, I forget, when adjusting Rcut, do I want to decrease the value (more negative) to reduce this effect or increase the value, (less negative). I was thinking it may be time to get out Avia and go into grayscale again and do a little tweaking.
     
  2. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    I recommend that you go to the keohi site or the ISF site to look at what a chromaticity chart looks like. This is the easiest way for you to eyeball your grayscale. Figure out where you are ... and where you want to be ... easy as 123.

    Cable and satellite channels are all over the map ...

    Regards
     
  3. Qui-Gon John

    Qui-Gon John Producer

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    Michael, thanks for the quick reply. When I did this the first time I used Avia and I think it was the pluge screen, serval bars of varying brightness. I got it pretty good, as I said, just reently noticed these discrepancies, and from what you said, most of that could be the cable channels themselves. But since it's been over 2 years since I set these parameters, I thought it might be good to go in and check them again. I just couldn't remember how Rcut worked. Did decreasing it remove red at low IRE's or did increasing the Rcut value make it 'cut' more, thus decreasing the red at low IRE's. I will look at the Keohi site, that is where I got the info to intially eyeball my greyscale.
     
  4. MichaelFusick

    MichaelFusick Second Unit

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    MicheaTLV,

    Is there a place where you can get a printed copy of the chart?

    I mean, how do I know that my printer is accurate, or that the color of my paper will effect it.

    (there is a huge difference between HP BRIGHT WHite paper, Photo paper, and everyday use copy paper, HP BRIGHT WHITE being the "bluest" )
     
  5. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    Unfortunately I don't know. The ISF site have the digtal drawings and that is all. Hopefully it is enough to give people the proper push in the right direction.

    The ones I have are from Sencore ... which were passed out at the Seminars.

    Regards
     
  6. MichaelFusick

    MichaelFusick Second Unit

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    I'll check it out.
     
  7. Mike Hamilton

    Mike Hamilton Stunt Coordinator

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    Mike,
    Get your computer monitor calibrated! Display Mate is only $99.00
     
  8. MichaelFusick

    MichaelFusick Second Unit

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    What is that?

    Where do I get it?

    I can change my greyscale on my computer... my monitor "Sony G series 21" .22 dot pitch" allows me to do this in 100 value incriments.
     
  9. Mike Hamilton

    Mike Hamilton Stunt Coordinator

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    It's on the ISF website (I think). Call Susan Silver, she'll advise you.
     
  10. MichaelFusick

    MichaelFusick Second Unit

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    OK...

    It won't work for anything but computer monitors though?
     
  11. Qui-Gon John

    Qui-Gon John Producer

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    Does contrast affect grayscale in any way. I have all my other settings, Drv & Cut for the best picture eyeballing it. When I decrease contrast further it seems to affect the purple hue problem slightly, when watching movies. Am I just imagining this?
     
  12. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    Contrast affects grayscale ... as does brightness.

    Contrast is kinda like the driver control but for all three colours at the same time.

    Brightness is like the cut control for all three colours.

    Regards
     
  13. Qui-Gon John

    Qui-Gon John Producer

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    So Michael, when I recalibrate, soon, I should get my contrast and brightness as best as possible, using my AVIA first, then tweak my DRV and CUT values to get the truest grays, whites and blacks on the pluge, right?

    Oh, and I assume before any of that get my convergence as tight as I can.
     
  14. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    The process usually does the contrast and brightness first. Get them set to reference levels. (AKA contrast to 20 ft-l light output on a 100 ire windowbox)

    Now do grayscale ... and when done ... check brightness and contrast levels again ... touch up ... and do grayscale again ...

    back and forth.

    Convergence ... slightly loose and tight actually has little impact on the grayscale calibration process.

    Regards
     

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