Why are black bars blacker than black?

Discussion in 'Displays' started by DanielKellmii, Jan 3, 2005.

  1. DanielKellmii

    DanielKellmii Supporting Actor

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    I have a 55in Mitsu RPTV. I love it. But why are the black bars blacker than any black in a movie?
     
  2. Ryan FB

    Ryan FB Second Unit

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    Some video sources can pass a "blacker than black" signal, which is sometimes used for the letterboxing bars. Usually when sets are calibrated, a PLUGE pattern is used to display a "blacker than black" background as well as a series of bars. The "black" bar is then calibrated to be indistinguishable from the "blacker than black" background. This test is available on most home theater calibration discs, such as Digital Video Essentials, and performing it should correct your black levels.
     
  3. ChrisWiggles

    ChrisWiggles Producer

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    They shouldn't be. Have you calibrated your set?
    You also may be viewing crappy video, as in some movies the picture areas have elevated black while the bars are correct.

    Use a test disc to determine for sure.
     
  4. DanielKellmii

    DanielKellmii Supporting Actor

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    I haven't calibrated my set yet. My AVIA disk is sitting (uselessly) above my TV.

    Oh the shame.
     
  5. ChrisWiggles

    ChrisWiggles Producer

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    So then why ask the question?

    go calibrate. takes 5 minutes.
     
  6. DanielKellmii

    DanielKellmii Supporting Actor

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    Hmmmm, a lot goes into that answer.


    Anyways, I just calibrated. D'oh! Much better now. But I still have to go back and do it when I am not so rushed.
     
  7. Jim Mcc

    Jim Mcc Producer

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    What do you guys mean by "blacker than black?". Does this setting exist on all DVD players?
     
  8. ChrisWiggles

    ChrisWiggles Producer

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    Jim: Blacker than black is data encoded below black. On 8-bit digital video(256 steps from 0-255), such as DVD, black is defined at digital level 16. Nominal reference white is placed at 235. Video data runs from 1-254. Below-black data is any data that falls below black(16), thus is data 1-15. Peak whites are data above 235.

    A video chain that is performing correctly will pass all the video data, including peak white details, and blacker-than-black. Many source devices, processors, etc, are incorrectly designed and clip image data (especially BTB).

    It is important to preserve both BTB and peak whites in a video system is possible for the best performance. In most consumer systems, hoping for this is a crap-shoot, and is confusing to test for. If you want more information on this, I have written a ridiculously long FAQ that is pretty much finished at this point.

    edit: note that blacker than black has nothing to do with IRE setup. Do not confuse the two.
     
  9. Bruce Phillips

    Bruce Phillips Auditioning

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    Chris, where are you going to be posting your FAQ? I'd like to read it.
     
  10. Brad E

    Brad E Second Unit

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    Me too.
     
  11. ChrisWiggles

    ChrisWiggles Producer

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