What happened to this picture

Discussion in 'General Discussion' started by morcguy, Sep 3, 2008.

  1. morcguy

    morcguy

    957
    Dec 29, 2006
    Minnesota
    This building is covered with corrugated siding. Did that interact with the sensor somehow? Is there anything that can be done to prevent this effect?


    2826948742_83b7997207_b.png
     
  2. tintingkc

    tintingkc Guest

    Looks like a reflection from the roof top in front of it.
     
  3. that is the MOIRÉ effect
    http://en.wikipedia.org/wiki/Moiré_pattern

    http://www.mathematik.com/Moire/

    it is often unavoidable
    i'm sure you've seen someone where an jacket on tv with an odd material pattern.... that causes such an effect

    i imagine a polarizing filter would have helped here
    but..... it would have been hard to predict
    the pattern of the material on the building
    and.... the exact angle of the sun against the building
    that's what caused this
    a few minutes before or after... it probably would NOT have occurred
     
  4. PeteZ28

    PeteZ28

    Oct 5, 2007
    Newtown, PA
    Do you see this in the full size 100% view or only when resized?
     
  5. morcguy

    morcguy

    957
    Dec 29, 2006
    Minnesota
    Thanks Greg.

    It shows up in the original captures as well as resizes.

    Capture NX has a function 'Color Moire Reduction", but its not listed in the help index and not much showing online as far as how to use it.

    So far it shows up in every sunset shot of that powerplant.
     
  6. 2X
     
  7. Jeff,

    You didn't state which version of NX you have but on my NX2 morie is located under "Camera and Lens Corrections". It is a simple setting with Off, Low, Medium and High. I hope this helps.

    MikeT
     
  8. morcguy

    morcguy

    957
    Dec 29, 2006
    Minnesota
    I have NX "1" - I see the setting, but when I change it, it does nothing.



    The pattern is definitely not a reflection.
     
  9. Nchesher

    Nchesher

    579
    Jul 7, 2006
    Lansing,MI
    I immediately thought some funny reflection too but it would be more oval due to the angle of the sun. It's one of the weirdest looking moire shot's I've seen.
     
  10. The very fine, almost vertical, lines from the corrugated steel must have more or less the same frequency (at seen from this distance) as the sensor pixels. Because the shot is slightly tilted, it causes the typical moire. Yes, it's rare to see it on such a large subject, but it is the same mechanism that creates moire with fabric for instance.

    To avoid it, shoot at a different angle (eg diagonal), move closer or further away from the subject so that the lines are either smaller than the sensor resolution (and therefore invisible) or larger (and therefore are resolved fully). To rescue this shot, use the Moire correction in NX, or add a slight blur to the subject, which can be applied selectively.