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Thread: Noise management - noise in dark areas of HDR

  1. #1
    OldCrow's Avatar
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    Noise management - noise in dark areas of HDR

    Do you folks have any solutions for noisy dark areas?

    I'm using Photomatix Pro to assemble my HDR images, and it seems to try too hard to find detail in dark areas.

    Overall I'm very happy with this image, but if you see the inset, the patch of sky is all noise.
    Will I be forced to paint it out in Photoshop? If the answer is "yes" I'm fine with that, I just want to make sure I'm not doing something wrong.

    Noise management - noise in dark areas of HDR
    Last edited by McQ; 13th November 2010 at 08:07 PM.

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    Moderator Dave Humphries's Avatar
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    Re: Noise management

    Hi Dave,

    I use PS Elements and purchased the Neat Image plug-in Noise filter.
    This is pretty good at getting rid of noise in a photo without destroying the detail.

    Thus my suggestion would be to use it on all the original capture images before they go near Photomatrix.

    However, I'm not a practicising HDR-ist, so I wonder if there isn't something that can be done like averaging between the images which can be a really effective NR method.

    Another method is to switch on the long exposure NR feature that is probably lurking in your camera, the downside is, each exposure may take twice as long. You might want to do this as well NR in PP.


    I have one question for you about the above image; are the wispy 'ghosts' I see the remnants of people walking into the first doorway? I do like the image again, nice composition, although I find (perhaps merely because of its colour temp), the 'planter box' behind the railings in bottom right corner a distraction.

    I would think these type of images might sell printed on canvas.

    Thanks,

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    Re: Noise management

    How many shots did you take, and over what EV range?

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    Re: Noise management

    Could be wrong but technically you should have less noise from HDR stacks (as long as from seperate images but I presume that's the case and TBH I love worms but that's not a can I want to open ) but I notice some tone mapping can introduce severe noise. Just a guess just I presume it is down to mapping contrasting tones in dark areas and how to sort it or if it's possible depends on the TMO and how it does things.

    Neat image is very nice but for this since there isn't that much in shadows to preserve and it's localised a health dose of clone layer>dust and scratches> layer mask- fill black and paint in the smooth shadows should do the trick quickly and easily without ruining or softening any of the detail in the rest of the image which neat image might do being a global edit. Ofcourse you could substitute dust and scratches for neat image in above method. Whatever your most comfortable way of NR is best way me thinks.

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    OldCrow's Avatar
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    Re: Noise management

    Quote Originally Posted by Colin Southern View Post
    How many shots did you take, and over what EV range?
    8 Exposures total;

    ISO 100
    F/5.6 @ 30sec, 15sec, 8 sec, 4 sec, 2 sec, 1 sec, .5 sec, .25 sec.

    How does that calculate out to EV range?

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    OldCrow's Avatar
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    Re: Noise management

    Quote Originally Posted by Dave Humphries View Post

    I have one question for you about the above image; are the wispy 'ghosts'...


    ...although I find (perhaps merely because of its colour temp), the 'planter box' behind the railings in bottom right corner a distraction.
    Yes, that's one of the employees going back into the building. It was 2:30 in the morning, and there were still plenty of people milling about. I tried several 8-second exposures and they all had people or reflections of headlights in the windows.

    Point well taken about the planter on the right. I'll play with the cropping.

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    Re: Noise management

    Quote Originally Posted by OldCrow View Post
    8 Exposures total;

    ISO 100
    F/5.6 @ 30sec, 15sec, 8 sec, 4 sec, 2 sec, 1 sec, .5 sec, .25 sec.

    How does that calculate out to EV range?
    That's a 7 stop bracket, at 1 stop intervals. If you try merging every 2nd one you'll probably get the same result in terms of dynamic range, but may reduce your ghosting.

    To answer your original question, ...

    ... I'm not sure. Probably just as easy to mask it and just deal to it locally.
    Last edited by Colin Southern; 21st June 2009 at 02:19 AM.

  8. #8

    Re: Noise management

    I use a plugin with my CS3, Imagenomics. I found it invaluable when I use auto ISO on my 5dmk2, useful image rate has increased.

    cR

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    Re: Noise management

    I'm using 'Neat Image' and find that it makes a great attempt at reducing noise in an image. Well worth the money, in my opinion. At the end of the day, a tripod and low ISO is the only way to go for reducing noise, though obviously in this case, that is all being done correctly already.

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    Re: Noise management

    Silly question about very dark areas - if there really is no light coming from an area, is fiddling with ISO and exposure going to produce anything but a pixel pattern corresponding to grey=95% black?

    Did use NeatImage when I was using PSE on 350D output and it is quite good, but to my eye always produced a slight 'oilyness' (but I was mostly using it on animals with black noses, which I couldn't get as close to as I would have liked). However also admit it has so many settings I may never have reached optimum. I now find NX2 gets as good results in 1/20 the the time by balancing sharpening with noise-reduction + sharpness tool. For something black, I would just paint it black (or 95% black) and have done.

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