Help me calibrate ideal white level!

Discussion in 'Archived Threads 2001-2004' started by Dave H, Oct 25, 2001.

  1. Dave H

    Dave H Producer

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    I'm going nuts trying to figure out what the ideal white level is on my TV. I'm using Avia - and while it's a very good disc to help calibrate - the disc needs to GREATLY improve the ability to help one calibrate ideal white level.
    My 61" Sony KP-61V80 does not bloom, and the power surge lines on the "white level" screen barely bend unless white level is turned up to 75%. Using the 50% greater than each rectangle is WAY TOO subjective.
    Judging by how white the bottom half of screen looks is my best judge, I guess.
    Right now my white level is set at about 33%. Does this seem right? I realize it will vary from TV to TV.
    Any suggestions?
     
  2. Guy Kuo

    Guy Kuo Supporting Actor

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    That's a taller order than you realize. Ideally, I'd say take out our colorimeter and put it on the screen. Adjust the white level to read between 14 to 20 foot lamberts. QED.
    Problem is not too many people have a video display capable colorimeter in their toolbox and photographic meters aren't going to help much either. So how do I relate to you a physical amount of light in terms of something you can compare against and is available everywhere and doesn't vary in brightness? I still haven't come up with anything practical. Ideas.....
    a. Flashlight bulb - changes brightness with battery age and make/model of bulb. Too unstable and wrong color.
    b. Sunlight through a window - almost the right color but varies in intensity during the day, thorughout the year and by lattitude.
    c. Laptop backlight - Varies from brand / model and even age of identical unit. Not standardizable.
    d. Burning butane flame at fixed distance from a screen. Pretty crude and reproducible and darned dangerous.
    e. Specify a one brand and make of photographic meter and an offset correction. Still expensive and likely to fail if anything changes in design of meter.
    You get the idea. We don't have a ready instrument by which you can measure light intensity readily so the best we can do is teach you two things.
    1. Find the redline point above which you NEVER EVER want to set the contrast. That is the RED LINE, not the ideal point. If red line on your engine is 7500 RPM (the equivalent of CRT just starting to bloom) you don't want to run your engine all the time at 7490 RPM do you? If you don't exactly know where the red line is (can't tell when it is blooming) it's okay as long as you keep things low.
    2. Have people set contrast as low as possible and yet still reproduces white in pictures as being bright enough to look white instead of dingy gray. That's a low setting way below red line and keeps the CRT's from wearing or burning in too quickly.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
     
  3. Dave H

    Dave H Producer

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    Guy,
    Thanks for the explanation. Based on your experience, does 33% seem to be a decent range? I guess the answer to white level is more of an ideal range - not an exact point.
    It's a gray issue. [​IMG]
    On the white level screen pattern, the bottom half seems white. Viewing several movies, this seems to be a good level without things looking too bright.
    Any more suggestions appreciated.
     
  4. Guy Kuo

    Guy Kuo Supporting Actor

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    It's a frustratingly vague point in the calibration for which I've yet to see a good answer.
    Yes, 33% sounds pretty reasonable a point to be ending up with the picture or contrast control. If you were up in the 70 or 80% range I'd be pretty worried. At 33% you're in the general ball park.
     
  5. Rick Radford

    Rick Radford Supporting Actor

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    Is this primarily aimed at RPTVs? Or does it apply to DV sets as well?
    ------------------
    --RR
     
  6. Guy Kuo

    Guy Kuo Supporting Actor

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    Direct view as well. Just because i t is direct view doesn't mean that the CRT's are immune to the same risks. The projection CRT's are even more sensitive to burn in and wear problems, but direct views are also vulnerable and shouldn't be run full out.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
     
  7. Lee-c

    Lee-c Second Unit

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    Hi guys,
    I have a new Wega 36 inch on the way and I was wondering if there were some general settings
    I should set the picture adjustments to. I have placed an order for Avia, so I'm just asking
    some general ballpark settings that will protect the screen and give pretty accurate results
    for watching movies on DVD until I can get more precise settings using Avia.
    Wega's seem to be a very popular pick among the forum regulars (which says volumes
    about the quality of Wega's) and perhaps some of you can share what settings work well
    on your Wega's.
    By the way, do the Wega's have separate controls for brightness and contrast, or just
    contrast to adjust the white level?
    Thanks for any help you can provide. [​IMG]
     
  8. Dave H

    Dave H Producer

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    Another thing I have been doing is viewing the end credits of a reference quality disc (Cast Away, in my case) since the credits are white on a black background. I start at 0 and keep increasing white level until the words are white and not dingy. just before they become somewhat unfocused or slightly blurred you know it's too much.
     
  9. Rick Radford

    Rick Radford Supporting Actor

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    When I ran the needle pulse and step tests, I did not see any line bending or blooming, even at 100% contrast.
    But to be safe (hopefully), I backed the contrast down to 65% on my 32" DV HDTV.
    I do wish there was a better way to zero in this calibration variable.. since it can be critical to the life of the set.
    ------------------
    --RR
     
  10. RyanDinan

    RyanDinan Stunt Coordinator

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    Guy,
    Didn't you post something a long while ago about making your own home-brew optical comparator?
    It went something like this...
    You empty out the contents of a VHS tape, leaving just the black shell, with the holes on one side, and the "windows" on the other.
    You then must line the inside of the cassette with neutral white paper using glue to hold it in place - thick paper is preferred, as it makes sure the black is totally covered. Cut the paper out from around the holes, making sure you don't let any of the black case show. Essentially, you're turing the inside of the case WHITE, but you want to still be able to see through the holes.
    The idea is that when the inside of the case is illuminated by a D65K light bulb, it will serve as a reference point to set your TV's white point. You hold the cassette up while looking through the holes. The holes will allow you to see the TV's white point, and the areas around the holes (inside of the cassette) will give you the white you're aiming for. You then adjust your DRV/CUT's so the white through the holes match the white inside of the cassette.
    The hard part is finding a D65K light bulb. People have said they've found them at Home Depot and Lowes, but I can never find one that's small enough.
    If you could find one the size of a standard light bulb, you could construct a more box-shaped enclosure, with the appropriate windows.
    -Ryan Dinan
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  11. Guy Kuo

    Guy Kuo Supporting Actor

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    That was a while back. It will get you roughly in the ball park, but still be off a bit in color. Most likely it will be a bit too green if one uses just regular old D type bulbs. The best bulb in terms of getting the right shade is the Lumichrome 1XX 6500 K fluorescent. Unlike most other 6500 K bulbs, it gets the amount of green vs magenta right. It's still a little bit too blue, but pretty good. Unfortunatley it is very hard to find (read impossible locally) and the smallest one is 18 inches.
    That means a bigger box and you still have the problem of getting the amount of brightness right. I could tell you a distance from bulb to a reproducible surface, but that still won't take care of the change in light output of the bulb as it ages. My bulb won't match yours in light output.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
     

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