Plasma calibration disk?

Discussion in 'Displays' started by ScottCarr, Feb 4, 2004.

  1. ScottCarr

    ScottCarr Second Unit

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    Hi

    is there a calibration disk that have been updated to include calibrations for plasma displays?

    thanks scott
     
  2. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    DVE and AVIA work fine for plasma.

    The rules for a good picture have not changed with the advent of plasma. You will find that many plasma sets simply don't measure up to the patterns these discs provide though.

    Regards
     
  3. Steve_L_B

    Steve_L_B Stunt Coordinator

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    Scott,
    Both Avia or DVE will do a good job with the possible exception of contrast. You are not likely to see any blooming or crushed whites with the standard patterns provided and therefore, you need to adjust it to the lowest level that you think provides adequate brightness for your viewing environment.

    The DVE disk does include a Snell and Wilcox pattern that includes a small white box within a slightly larger less white box. Many plasma owners have found this to be the most useful pattern for setting contrast by simply adjusting contrast until the inner box is visible.


    Regards,
    Steve
     
  4. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    The 10 step gray sweep pattern in AVIA and DVE can be used for determining contrast.

    When too high, the bright boxes get crushed ... aka blend together.

    regards
     
  5. Guy Kuo

    Guy Kuo Supporting Actor

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    That's right. The underlying tests haven't really changed as the display technology changed. However, the instructions and methods of using those standard signals may need some modfication. Calibrators know this, but lay enthusiasts need things spelled out step by step. The Avia disc's patterns were already set up for digital displays like plasma, but the on disc instructions are keyed to the most common display type of the consumer at the time of AVIA's release. As a result, most people don't realize that the 98 and 99 IRE moving "white" bars in AVIA are for detecting clipping of highlights on digital displays. Also the 1 and 2 IRE above black moving bars actually should both be visible on a digital display.

    The patterns were set up for the next generation but it was necessary to write for the average CRT RPTV using consumer. Those displays often suffered poor black level stability and drifted the intensity of the black bars up and down as the picture intensity changed. The narrative instructions said to make the leftmost black bar disappear to achieve a workable compromise. Today's digital displays have much less of a problem with black level stability. The visibilty of the leftmost black bar doesn't change as much as average picture level rises. On the old sets it did tremendously.

    ---- Do you want the white or black bar on the left to be A: nearly invisble? or B: invisible?

    The leftmost moving black bar is just barely ABOVE black and therefore should be just bright enough to be barely visible but defintely present on a digital display. A good way to do the adjustment is to use the Black Bars + Log Steps pattern in AVIA. Drop brightness down enough to make the leftmost black bar disappear then go back up just enough to make it reappear. I suggest the Black Bar + Log Steps pattern because it loads the video amps slightly but doesn't scatter a huge amount of light to obscure the black bars.



    --- Do you want the white or black bar on the right to be A: barely visible? or C: clearly visible?

    You want the rightmost white bar to be visible about halfway as much as the left white bar. Some material is authored to have white slightly higher than standard so it is reasonable to go yet a few clicks down on the contrast control to allow for more headroom.

    Once you set contrast with the Needle Pulse pattern, go to the Black Bars + Log steps and verify that the middle of the range gray steps are the same color of gray as the topmost step. If you see a big color shift between the middle and the top, you may need to further drop the contrast control to achieve good tracking. Just don't go so low that the image becomes too dim. On some digital displays, grayscale tracking falls apart as you raise the contrast control. The log steps become different tints when that happens. If you set is one which suffers that problem, you may need to keep the contrast control well below the point at which you see clipping of the moving white bars.


    BTW, do the above for digital displays. The method on the disc should still be used for CRT RPTV's. Also, I have developed some new features in Avia PRO to make things even accurate but that product is definitely not for the consumer.
     
  6. ScottCarr

    ScottCarr Second Unit

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    Guy,

    Thank you for taking the time in responding to my question. I do have the Avia disk and after running it last night and then trying to watch a movie today I couldn't see a thing, just a little too dark.

    From reading your post the hints will definitely help.

    Maybe tonight I will have a chance to play in between periods of the Colorado - Detriot hockey game.

    Thanks
    Scott
     

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