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Thread: HDR Noise in Photomatrix

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    JK6065's Avatar
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    HDR Noise in Photomatrix

    I have a question about noise in darker areas after hdr prcessing in Photomatix.
    When I create a HDR in Photomatix I almost always get random noise in the darker areas and shadows. Does this depend on the level of processing in Photomatix? (If i kind of overdue the HDR effects, smooting and saturation it clearly is that way.)
    Or is it noise produced by my (compact) camera? The noise isn't vissible in the single unprocessed photo's.
    Is ther something I directely can do against it and are there other photomatixusers here?

    HDR Noise in Photomatrix

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    Moderator Dave Humphries's Avatar
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    Re: HDR Noise

    Hi Jeroen,

    I have to say I am struggling to see noise in what I would call "the darker areas" of the shot (e.g. the bushes and masonry of the building), but think I can see something in the clouds, sky and the shiny metal clad building on the right, what I might call the HDR darkened areas. I think this is just a mis-understanding of language.

    I'm not an HDR person myself, so I'm afraid I can't help beyond that clarification.
    This fact will also bias my following personal opinion.

    I am not a fan of the "bright halo's effect" on the transitions between dark and light areas, it is (unfortunately IMHO) almost expected on the sky, but on that shiny metal building, I think it looks really rather odd - why would there be a bright bit close to the ground like that? To me it looks almost floodlit from behind the hill. The rest of the photo isn't "unreal" or surreal enough for me to accept things like this.
    With the sky; I wouldn't have a problem if the HDR grey clouds touched the buildings and ground, because actually, that's probably how my eyes would have seen it.

    I dunno, maybe I'm missing the point
    maybe I'm too old and grumpy and should be ""put out to grass"! (retired)

    Sorry,

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    Re: HDR Noise

    As Dave pointed, the image doesn't look that noisy to me.

    Anyway, noise in HDR images has two sources working together:

    1. Camera noise: if the camera sensor would generate no noise at all, we would never see any noise in the final image no matter how agressive the processing was.

    2. Photomatix fusion and tone mapping process: Photomatix is far from being an optimum image blender in terms of noise. It usually makes some of the initial noisier images participate in the final result because of the progressive blending it performs. In addition to this, Photomatix tone mapping routines provoque local contrast enhancement that makes noise much more visible than it was in the original files.

    I agree with Dave that automatic tone mapping tools seldom produce pleasant results. Lighting inconsistencies are usual, making areas of the image brighter than others that were more luminous in the original scene. This provides an unrreallistic look making sometimes hard to find where the real light sources were.

    Regards

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    Re: HDR Noise

    Thanks for your reply's
    I agree Photomatx has got some 'strange' effects on HDRs but the reason why I use Photomatix rather than PS CS2 for HDR processing because of the more dramatic look of the HDRs. With Photomatix you can set a kind of atmosphere which PS doesn't. I've tried this particular HDR in PS an this just gave me a nearly original looking photo with increased dynamic range. It was less noisy (especially the darker clouds look noisy to me) but it wasn't the way I want it.

    I think camera noise is the biggest issue, especially when looking to me budget
    But about the pp there's so much to learn for me.

    And about the language mis-understanding. I'm working on my english and also the photographer's terms

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    Moderator Dave Humphries's Avatar
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    Re: HDR Noise

    Hi Jeroen,

    Let me say everyone here that uses English as a second language automatically commands a level of respect (in my head at least) that I do not afford myself because I found a second language 'too difficult' when at school, even after 4-5 years slogging away at it, so I didn't persevere. For what it's worth, I didn't do too well in English either , prefering maths, technical drawing, sciences and engineering.

    As to photography; we're all learning here.

    As Guillermo says, the noise is not that bad, and may respond to say, Neat Image, even now in the final edit. Or, next time, run each original exposure through it before HDR (even if you can't see the noise, it may help - something to experiment with).

    Best regards,

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    Moderator Dave Humphries's Avatar
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    Re: HDR Noise

    Hi again Jeroen,

    I thought I'd run it through Neat Image (as I already have it), what do you think?

    HDR Noise in Photomatrix

    I just did my 5 step Neat Image process TM, but I made sure to sample on the clouds.
    It complained the sample was too small, and that it had variations in the Yr channel (this was the best I could achieve working from a small image), but nevertheless, I think it has removed a lot of the problem.

    Cheers,
    Last edited by Dave Humphries; 30th July 2009 at 09:43 AM.

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    Re: HDR Noise

    Hi Jeroen - Interesting post in some ways. I've found that Photomatix Pro does give rise to unacceptable noise in dark/shadow areas if you process a single file as a pseudo-HDR. Processing, say, three files at 0 and +/- 2 stops does not cause a problem. However, I think care has to be taken on using what is now called the "smoothing" control (in Version 3.2). Higher values give a more natural look, lower values a more painterly look. Noise may be amplified by lower values.

    Hope this helps.

    Cheers

    David

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    Re: HDR Noise

    @ David, that is true. I found that staying close to the orgininal photo (so be gentile with the strength, smooting and saturation) does make it look less noisy, but it's just a compromise depending on what you want to achieve.

    @ Dave, stunning result you managed there. About that Neat Image: It's a bit expensive ... *cheap ass smile* .
    I'll consider bying it.

    I found out that averaging images give me very good results. I'm going to try making a HDR like that these days. Just averaging each singele image before HDR processing. Although cameramovement is going to be a big problem.

    But anyways, thanks for these helpfull comments

  9. #9
    Moderator Dave Humphries's Avatar
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    Re: HDR Noise

    Quote Originally Posted by JK6065 View Post
    I found out that averaging images give me very good results.
    Another thing that I find helps is the down-sizing for web/here, if you have around 12MP, i.e. about 4000px width to start and bi-cubic re-size that down to 1000, it also improves the noise appearance. It obviously needs to be the penultimate thing you do though (i.e. do all the HDR stuff at 4000px). The last thing you do being the final sharpen.

    Neat Image is only about 30 Euros for the 8 bit version, I wouldn't have called that expensive compared to PS CS4, but might agree if comparing to GIMP

    Cheers,

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