Noise: digital or analogue?

Discussion in 'Darkroom Developing and Printing' started by Anton Shepelev, Mar 13, 2010.

  1. Hello all,

    Could an expert here tell me origin of
    the color noice on the referred photo?

    http://img31.imageshack.us/img31/2010/grain.png

    It's a fragment of a scanned photo (slide film), and
    I'd like to know whether it is scanner noice or film
    grain. The noice I am taking about is best seen on the
    women's T-Shirt.

    Thank you in advance,
    Anton
     
    Anton Shepelev, Mar 13, 2010
    #1
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  2. looks like dirt in the emulsion.
     
    Jean-David Beyer, Mar 13, 2010
    #2
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  3. Ackshooly, the woman's T-shirt looks OK to me: there's what looks like
    dirt everywhere else that's lighter. Is this the "noise" you're
    referring to? In that case, I think it's just dirt, not noise.

    You may need to clean the slide before rescanning it.
     
    David Nebenzahl, Mar 14, 2010
    #3
  4. Anton Shepelev

    Jeremy Nixon Guest

    There are a few things going on here, and I suspect the other replies were
    about the wrong one. The most obvious is the specks of dirt all over the
    place; I assume you're not asking about that because the cause is obvious.

    Then there's the "texture" you get, most prominently in the T-shirt; that's
    the film grain and looks fine to me. Finally, there is what looks an awful
    lot like digital chroma noise, and I suspect that's what you're actually
    asking about. I believe that is also simply film grain, and it's normal
    (in my experience, and I'm not a Top Expert) for color film scans.

    I determined to my satisfaction that it wasn't digital noise (in my own
    scans) by cranking up the scanner to 16x multi-sampling, which should
    eliminate any trace of digital noise, and that pattern didn't change at
    all. That's just the way it looks.

    Having said that, setting Color Noise Reduction to 10 in Lightroom (or
    Camera Raw) will eliminate it. (Yes, you can do that on a TIFF from a
    scanner.)
     
    Jeremy Nixon, Mar 14, 2010
    #4
  5. Jeremy Nixon:
    Thanks to everybody for their replies. I got another proof of Jeremy's
    suggestion: setting a wrong focus on the scanner blurrs away the image
    together with the 'noise', which turns to be how grain looks to the scanner.

    Now another question:
    On optical prints, even at big scales (like 1 x 1 m from 60 x 60 mm film)
    there's no such noise visible. Does is mean they are printed with sifted
    focus, or is it the natural blurring in the enlarger? One way to check it
    would be to get my grainy scan printed in a fotolab without preprocessing.

    I am not even sure this grain noise needs to be cleaned up before printing...

    Anton
     
    Anton Shepelev, Mar 20, 2010
    #5
  6. Anton Shepelev

    Jeremy Nixon Guest

    Good thought, I didn't even think of that. :)
    Scanning seems to accentuate grain. I gather it has to do with the light
    source being harder.

    It's worth noting that almost all labs now do prints by scanning the
    negatives.
    Are you printing optically or from the scan? If you're printing from the
    scan, the "noise" is really quite small. But like I said, you can eliminate
    it with one slider in Lightroom. If you're ultimately printing optically
    then it's probably irrelevant.
     
    Jeremy Nixon, Mar 21, 2010
    #6
  7. Thank you, Peter and Jeremy.

    Jeremy:
    I am prining both ways (but digital is 90%). I
    agree that on optical prints (even very large like
    100x100 cm from a 60 mm film) grain is almost
    invisible). Judging from what they did at the
    lab, which can be bad tuning of the enlarger and
    other factors. But I am going to try b/w printing
    myself.

    Anton
     
    Anton Shepelev, Jun 20, 2010
    #7
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