1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

THX Optimode

Discussion in 'Blu-ray & DVD Players & Recorders' started by bowenjones, Nov 2, 2002.

  1. bowenjones

    bowenjones
    Well-known Member

    Joined:
    Oct 24, 2002
    Messages:
    2,786
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Wales
    Ratings:
    +443
    Can someone please tell me why some players can display
    the drop shadow of the THX logo in the optimode video test
    and some can't.
    My old Samsung 709 could but my new Toshiba 220 cannot.
     
  2. Adam Barratt

    Adam Barratt
    Standard Member

    Joined:
    Aug 9, 2000
    Messages:
    170
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    16
    Location:
    New Zealand
    Ratings:
    +0
    NTSC, the television system used in America, uses a brightness value of 7.5IRE to indicate the total absence of light (ie. black) and 100IRE to represent maximum brightness (white). For PAL and Japanese NTSC, 0IRE is used as the black or 'pedestal' level. Because 0IRE and 7.5IRE both represent the total absence of light for NTSC, many DVD players do not accurately reproduce any material below 7.5IRE (called 'below black').

    The THX Optimizer test pattern you mention is a variation of the standard PLUGE test pattern. It includes material that displays at around 3.5IRE, 7.5IRE and 11.5IRE (the letters, 'THX', are around 11.5IRE, the general background of the pattern 7.5IRE and the drop shadow around 3.5IRE or so).

    If a DVD player is incapable of displaying below black, then it will only reproduce the letters and the background accurately and not the drop shadow.

    Below black allows easier calibration of brightness, but that's all. As there isn't any material of importance present below 7.5IRE (since there can't be anything blacker than absolute black: 7.5IRE), not being able to reproduce it makes no difference when playing ordinary DVDs.

    To answer the question more simply, some DVD players don't reproduce the drop shadow because they don't have to. They're not going to come across this level on any actual DVD, just test patterns.

    Adam
     
  3. bowenjones

    bowenjones
    Well-known Member

    Joined:
    Oct 24, 2002
    Messages:
    2,786
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Wales
    Ratings:
    +443
    Thanks Adam.
    I did think that I might be missing out on some
    resolution but your explaination has come as a
    relief.
     
  4. Squirrel God

    Squirrel God
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hi Adam,

    What sort of players will display the drop shadow? In other words, how high end does one have to go in order to see this? Is it only the very top of the range players or does it just generally vary between manufacturers?

    Thanks.
     
  5. Adam Barratt

    Adam Barratt
    Standard Member

    Joined:
    Aug 9, 2000
    Messages:
    170
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    16
    Location:
    New Zealand
    Ratings:
    +0
    It varies, and not according to the price of the player. Early Panasonics weren't capable of reproducing blacker than black, but all of their newer models can. Sony's first generation players (1997) were capable of reproducing blacker than black, then their second generation players weren't and their newer players can again (deep breath). Pioneer players all pass blacker than black as far as I know.

    Toshiba have in the past advertised that all of their players are able to reproduce blacker than black, which makes bowenjones' problem a bit puzzling.

    Adam
     
  6. Squirrel God

    Squirrel God
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Thanks Adam :)
     
  7. bowenjones

    bowenjones
    Well-known Member

    Joined:
    Oct 24, 2002
    Messages:
    2,786
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Wales
    Ratings:
    +443
    The shadow definitely isn't there - region 1 ntsc or region 2 pal.
    Perhaps Toshiba has changed the specs again.
     
  8. supertech

    supertech
    Standard Member

    Joined:
    Dec 11, 2002
    Messages:
    4
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    3
    Location:
    merseyside
    Ratings:
    +2
    I have found that toshiba DVD players will show the drop shadow
    in S-Video mode and RF!

    Steve
     
  9. gingerone

    gingerone
    Well-known Member

    Joined:
    Dec 10, 2002
    Messages:
    2,383
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    86
    Ratings:
    +285
    My Pioneer dvd 525 can not display the drop shadow!
     
  10. adox

    adox
    Banned

    Joined:
    Nov 5, 2002
    Messages:
    688
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    19
    Location:
    dublin
    Ratings:
    +0
    my pioneer dv350 does display the drop shadow
     
  11. Rookies

    Rookies
    Well-known Member

    Joined:
    Jan 4, 2003
    Messages:
    4,898
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    103
    Ratings:
    +344
    Does the new Sony 905 show this drop shadow does anyone know for sure?
     
  12. lab

    lab
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    My cheapie chinese dvd player displays the drop shadow and all 10 black boxes on thx optimiser,plays ntsc prog scan and to my amazement pal prog scan as well,although it wasn`t advertised with this feature.Not bad for 125 squid!!!
     
  13. SimonO

    SimonO
    Active Member

    Joined:
    Nov 4, 2002
    Messages:
    3,193
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    71
    Location:
    Hertfordshire
    Ratings:
    +64
    Any idea why my new Sony KV-36FS76U will not display the THX drop shadow when my previous KV-32FQ75 would, both from the same DVD player..?
     
  14. Gary Lightfoot

    Gary Lightfoot
    Distinguished Member

    Joined:
    Apr 6, 2001
    Messages:
    12,302
    Products Owned:
    1
    Products Wanted:
    1
    Trophy Points:
    166
    Location:
    Surrey. UK.
    Ratings:
    +2,016
    I think you'll find that the optimode is designed for the disk it is on - abd some show the drop shadow and some don't - all on the same set-up.

    Use something like Avia or Video essentials for calibration, as they'll be consistent, though you have to calibrate for PAL or NTSC unless the player has 0ire/7.5ire switching for NTSC.

    Gary.
     

Share This Page

Loading...