non-linear horizontal distortion in anamorphic DVD

Discussion in 'DVD Video' started by arie, Jun 6, 2006.

  1. arie

    arie Guest

    Recently, I have acquired a DVD movie "Mamma Roma" by P.P.Pasolini
    issued by Criterion, which is famous for its high-quality digital
    remastering of old movie classics. The disk is anamorphic 16:9, and the
    image fills the screen of my 16:9 LCD display (BENQ, 32") in the
    Full-screen or Anamorphic mode, supposedly undistorted. To my great
    disappointment, when the movie gets to slow horizontal panning takes of
    a static landscape (there are quite a few of them in the film), I see
    gradual distortion of the objects in the frame as they cross the screen
    from, say, the right margin to the center and then to the left margin.
    This effect is very disturbing to eyes. To assess it quantitatively, I
    made the movement pause several times and measured with a ruler the
    width of a certain object in different positions on the screen. It
    turns out that, compared to their width in the center, the objects are
    by 35-40% (!!!) wider near the side edges of the screen. The effect is
    the same whether I watch it through a PC (with PowerDVD software) or
    through a stand-alone DVD player. However, when I set the display to a
    4:3 mode and keep the original aspect ratio of 16:9 (with black bars on
    all four sides of the display) the object widening is much smaller
    (about 10%), and the eye practically does not discern it. It is clear
    that a part of the fault lies in the disk information itself, but a
    greater part pertains to other components (decoding software and
    hardware? properties of the display?). I should greatly appreciate a
    professional explanation. Are there ways to solve this problem? I
    should note that I have run a number of other anamorphic disks and
    haven't felt this phenomenon, but now I realise that this is because
    most of panning scenes are accomponied by movements of dynamic objects
    (people, cars, etc.), and this blurs the effect.
    arie, Jun 6, 2006
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  2. arie

    Sean O'Hara Guest

    In the Year of the Dog, the Great and Powerful arie declared:
    This has nothing to do with the DVD -- it's how the movie was filmed.

    35mm film, which most movies are shot on, have a squarish frame. To
    create a widescreen image, there are two main methods. The first is
    to shoot "flat" and then crop off the top and bottom of the frame to
    the intended aspect ratio. The second is to use anamorphic lenses,
    which capture a wide vista and compress it horizontally to fit on
    the 35mm film. When it's projected in theater, a lens is used which
    reverses the process. (Note that "anamorphic" in the sense of lenses
    is completely different from "anamorphic enhancement" on DVDs.)

    Anamorphic lenses -- and this is especially true with the earliest
    ones -- create distortions that become noticeable when the camera
    pans around.

    Sean O'Hara |
    Leela: Uh, Professor, are we even allowed in the Forbidden Zone?
    Professor Farnsworth: Why of course! It's just a name. Like the
    Death Zone, or the Zone of No Return. All the zones have names like
    that in the Galaxy of Terror.
    Sean O'Hara, Jun 6, 2006
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  3. arie

    arie Guest

    Thank you, Sean.
    I think you are right. I observed this phenomenon on another Pasolini's
    movie, "Gospel according to St. Mathew"released by Tartan. Probably,
    there was a problem with the lenses he used at that time (about

    arie, Jun 6, 2006
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