Problem with the Avia test pattern for brightness

Discussion in 'Displays' started by Bill Wheatley, Feb 9, 2004.

  1. Bill Wheatley

    Joined:
    Jun 30, 1997
    Messages:
    34
    Likes Received:
    0
    Trophy Points:
    0
    So after a weekend thoroughly enjoying my new Dell 200mp projector, I decided to pop in my Avia DVD and do a few tweaks.

    During the Black Bars + Half Grey test pattern for brightness I could not make the moving black bars on the left appear no matter how high I set the brightness on the projector.

    When I first unboxed the projector here at work, I used the Avia disk and the test pattern worked fine. I did try two different DVD players at home and neither displayed the black bars. So, the only difference would be the DVD player here at work, which is not progressive scan (both my players at home are) and the length of the component cable used. The cable that comes with the projector is about 3 feet long and the one I use at home was a 50’ cable I ordered from Dell.

    Being brand new to projectors I’m just looking for a little info on this. Is my cable too long? Is this somehow normal? The picture still looks pretty good to me (a confessed neophyte) but is this test pattern telling me that I’m losing some detail?

    Thanks!

    Bill
     
  2. Steve_L_B

    Steve_L_B Stunt Coordinator

    Joined:
    Sep 26, 2002
    Messages:
    133
    Likes Received:
    0
    Trophy Points:
    0
    Make sure that your DVD player and projector are set to output and receive video with the same black level. It sounds like the DVD player is set to output black at 0IRE and the projector is set for 7.5IRE. Try to set the projector to 0IRE, although it doesn't really matter which level you use as long as they are the same. If you can't change the projector, the DVD player should have a setting for black level (sometimes referred to as "setup" or "enhanced black").

    -Steve
     
  3. Guy Kuo

    Guy Kuo Supporting Actor

    Joined:
    Mar 6, 1999
    Messages:
    581
    Likes Received:
    0
    Trophy Points:
    0
    -----is this test pattern telling me that I’m losing some detail? -----

    Yes. The total inability to make the darker (left) bar become visible indicates that near black shadow details are not being displayed in the system. Steve has some good suggestions above.
     
  4. Bill Wheatley

    Joined:
    Jun 30, 1997
    Messages:
    34
    Likes Received:
    0
    Trophy Points:
    0
    Hey thanks for the info guys...

    Steve, you're suggestion was dead on. I changed the video black level on both my dvd players to "lighter" and the black bars in the test pattern appeared.

    I'm not excatly sure the purpose of those settings, but would like to learn more. Could either of you point me to a good website that has some information on the subject?

    Thanks again,

    -Bill
     
  5. Steve_L_B

    Steve_L_B Stunt Coordinator

    Joined:
    Sep 26, 2002
    Messages:
    133
    Likes Received:
    0
    Trophy Points:
    0
    Bill,
    Glad you were able to correct it. Here is a link to an article to get you started. If you do a search on this forum, you will find many posts by Guy Kuo (and others) on the subject of 0IRE versus 7.5IRE black level.

    Black Level and Picture

    Regards,
    Steve
     
  6. Steve_L_B

    Steve_L_B Stunt Coordinator

    Joined:
    Sep 26, 2002
    Messages:
    133
    Likes Received:
    0
    Trophy Points:
    0
  7. ChrisWiggles

    ChrisWiggles Producer

    Joined:
    Aug 19, 2002
    Messages:
    4,791
    Likes Received:
    1
    Trophy Points:
    0
    I beleive the linked Poyton article is incorrect re the blacklevel adjustment? My understanding was that this shifted the curve ALONG the curve, not moving the whole thing up and down. Not sure though, as I just returned that book this morning.
     

Share This Page