Noise Ninja custom noise print- worth the effort for stacked photo??

Discussion in 'Digital Photography' started by Jason Sommers, Jan 18, 2005.

  1. I am an amateur astronomer and use a digicam to take pictures of the solar
    system. I take up to 100 photos and then stack the photos into one to
    reduce noise levels. However, sometimes a 100 photo composite isn't enough
    for the amount of noise I get. I have Noise Ninja, but don't use it much
    because I am never happy with the results as it seems to smooth the images
    too much, washing out details. However, I have never created a custom noise
    print for my camera, using the checkerboard pattern and a defocused shot.
    My big question is: would a custom noise print created this way be worth the
    effort and would the results be better than just the box sampling I do now
    from the existing image? Also, I'm guessing that I would need to take 100
    such samples since 100 images make up a composite, but not sure how to go
    about it. I would think that each image would have to have noise reduction
    before stacking for this to work and that's how I was going to do it. So,
    yes, a lot of effort involved, but would the result be worth it?

    Thanks,
    Jason Sommers
     
    Jason Sommers, Jan 18, 2005
    #1
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  2. If reducing the random noise by a factor of 10 isn't enough, you
    should indeed investigate post-processing noise reduction per image
    (assuming you cannot reduce noise by preventing it). Do you do
    darkframe/offset/bias/etc. subtraction?
    I'm more familiar with Neat Image, but these programs are probably
    equally suitable. Spend some time in tweaking the settings (often
    means reducing the default amount of reduction).
    You should, as there is no suitable featureless area in deepspace
    images you could use to create a noise profile. Do make sure that you
    don't make this profile until the darkframe subtraction etc. has been
    done first.
    Although it's hard to judge without examples I am almost certain it
    will improve things a lot. A program like Neat Image can run
    unattended in batch mode once you've figured out the optimal settings.
    Yes, individual noise reduction per image (in batch mode), not on the
    stacked result.
    Again, make sure you've done all you can to prevent the noise in the
    first place, because all post-processing carries the risk of signal
    loss. There would be not much benefit if the noise reduction doesn't
    improve the S/N ratio.

    Bart
     
    Bart van der Wolf, Jan 18, 2005
    #2
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  3. Jason Sommers

    eawckyegcy Guest

    You take a hundred images and wonder if a few more is worth it? You
    have a weird "effort" calculus.

    But whatever.

    I can't comment on "Noise Ninja" (which, in the absence of other data,
    sounds more like marketing than principled noise reduction -- but
    perhaps silly names are an indication of a saturated market than
    anything else), but whatever "custom noise print" you may record with
    your sensor most likely won't hold up once you start stacking up
    mis-aligned frames.

    If it was me, I would just stack up several hundred images, not just a
    mere hundred. This is, after all, what everyone else does:

    http://www.trivalleystargazers.org/ken/Saturn/Saturn.html

    Many other hits. Also note that stacking is the only way to reduce
    noise without sacraficing image detail (or, equivalently, making
    assumptions about the structure of the image -- assumptions which Noise
    Ninja and its ilk necessarily make.)
     
    eawckyegcy, Jan 18, 2005
    #3

  4. Not sure what you mean by this "effort calculus" but in astronomy, one is
    limited by the rotation of the object being imaged. This isn't much of a
    problem with wide field deep space objects, but with narrow field planets,
    which will show a "rotational blur" after a surprisingly short time, the
    total number of stacked frames is limited. I can only capture about 100
    frames at a time with my digicam before rotational blur becomes an issue,
    but with dimmer targets like Saturn, 100 frames isn't enough and, other than
    increasing telescope aperture, I am trying to find the next best way to
    reduce noise.
    Like I said, digicams are not capable of that. I haven't looked at the
    link, but some use webcams, which can do this, but I don't like the dynamic
    range of webcams which is why I've stuck with my digicam.
    That's true, but once you reach your stacking limit and noise is still an
    issue, you seek out other options which is why I was asking about going to
    the trouble to make a noise print.

    Jason
     
    Jason Sommers, Jan 18, 2005
    #4
  5. In other words, I think you're saying just take an extra 100 "noise print"
    shots at the time. Well, that is what I will do in the future but with the
    existing frames, noise prints will have to be created after the fact-
    something I am considering and was the point of my original question because
    it means a lot more work.....
    Perhaps, but it's rare to find a sharp solar system object with that many
    frames. There is a tradeoff. Reducing noise by stacking more frames than
    necessary causes smoothing and loss of detail.

    What
    A Coolpix 4500. Yes, webcams seem to be at the forefront, but the dynamic
    range still suffers even after stacking many many frames. Digicams, and
    likewise commercial astronomy CCD cameras, are capable of producing better
    images IF noise is not an issue.
    I appreciate your analysis, but it deviates from the point of my original
    question.

    Jason
     
    Jason Sommers, Jan 19, 2005
    #5
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