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Thread: How to avoid image noise in a low-light HDR photo

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    How to avoid image noise in a low-light HDR photo

    I've made a number of attempts with HDR under low light conditions and have been plagued with more noise than I need. I know there are programs such as Noise Ninja to help in such cases but I'd be grateful for any tips for avoiding it in the first place. Thanks in advance

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    Re: How to avoid image noise in a low-light HDR photo

    Image noise really should not be a problem with HDR photos since the shadow portions of your final HDR can be created from an overexposed (and thus less noisy) original. Just make sure that in your sequence of shots at different exposures that the one with the longest exposure makes the darkest portions of the scene very bright.

    That being said, fixed pattern noise the only type of noise which *can* become a problem and is unavoidable using the above technique. This type of noise is also not very amenable to Neat Image, Noise Ninja or other noise reduction software. Turing on long exposure noise reduction in your camera (if available) can help. The only real ways to reduce this type of noise is to have a shorter exposure time (by possibly using a higher ISO or less depth of field), or to take the photo in the cold. Using a higher ISO might sound counter intuitive because this will increase noise, but this is the random noise variety which is much easier to remove using noise reduction software. Just a thought.

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    Re: How to avoid image noise in a low-light HDR photo

    When using photomatix, I get some noise that doesn't make a lot of sense to me.

    I know some people report much better results from other programs like Artizen.
    A member onthese forums was developping a very promising software as well.

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    Re: How to avoid image noise in a low-light HDR photo

    Quote Originally Posted by xeliex View Post
    When using photomatix, I get some noise that doesn't make a lot of sense to me.

    I know some people report much better results from other programs like Artizen.
    A member onthese forums was developping a very promising software as well.
    Noise is not produced by your HDR software. Noise ALREADY WAS in your RAW files, because you didn't expose your RAW file enough. So Photomatix is not guilty, when noise appears is your fault. Expose more.

    BR

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    Re: How to avoid image noise in a low-light HDR photo

    I always thought that was the case until I started seeing noise in a sky above marathon runners. I have yrt to try the other HDR converters.

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    Re: How to avoid image noise in a low-light HDR photo

    Quote Originally Posted by xeliex View Post
    I always thought that was the case until I started seeing noise in a sky above marathon runners. I have yrt to try the other HDR converters.
    If you send me the RAW file of the maraton runners, I can show you all the noise that was there in the RAW data. Photomatix just made it visible when applying its agressive tone mapping local contrast enhancement.

    I don't agree with using tone mapping tools that make the user loose control over the process. All information that was there can be obtained manually, and without disgusting late hour surprises. It just requires some more effort than Photomatix's button click.

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    Re: How to avoid image noise in a low-light HDR photo

    BTW a fellow has just made a noise test, by blending 3 RAW files from an Olympus E-510 using Photomatix 3, Zero Noise and only one of the RAW files developed with Perfect RAW (DCRAW):


    25% crops (nearest neighbour to preserve SNR)
    How to avoid image noise in a low-light HDR photo

    50% crops (nearest neighbour to preserve SNR)
    How to avoid image noise in a low-light HDR photo

    The complete test is here. It is clear to me that Photomatix is not a tool focused on noise reduction (it didn't optimise noise reduction in the shadows nor recovered the nearly blown sky). It focuses on tone mapping but not in capturing the maximum dynamic range from the scene.

    BR
    Last edited by _GUI_; 2nd June 2008 at 12:31 AM.

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    Re: How to avoid image noise in a low-light HDR photo

    GUI, I see in a post by Manuel Llorens a reference to ZeroNoise 0.99, yet your own page offers a link to .91. Is there a newer version available? Also, what's TOP SECRET seen in the samples above?

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    Re: How to avoid image noise in a low-light HDR photo

    Quote Originally Posted by DanielJ View Post
    GUI, I see in a post by Manuel Llorens a reference to ZeroNoise 0.99, yet your own page offers a link to .91. Is there a newer version available? Also, what's TOP SECRET seen in the samples above?
    no, the 0.99 was a mistake of Manuel; at this point I cannot even write any new version in my PCs, I am having a lot of trouble to reinstall Visual Studio 6 because it is interferring with VS 2005 and Vista.
    The TOP SECRET was just a joke, he used Genuine Fractals to focus and 'recover' texture in the final image. But if he didn't speak about it I preferred not to do it either

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    Re: How to avoid image noise in a low-light HDR photo

    GUI, the content you provided in this post is much appreciated.

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