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Author Topic: Problems with Noise in Dark Areas  (Read 11967 times)

bjd

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Problems with Noise in Dark Areas
« on: October 14, 2012, 03:59:27 AM »
Hi,
I have read a bit about this problem, but dont really understand why it is happening in some cases. Take the picture below (just a part of it).
That was created from 3 RAW files at -1.5,  -0.5 and +0.5EV.  Its the red pixel noise in the tree that is disturbing. None of the original pictures has that noise. In fact the tree was one of the darkest parts so I expected the information for that part of the picture to be taken from one of the more exposed shots, and
therefore have very low noise.
I processed the HDR in Photomatix. I have not been able to get rid of the noise in PS so I need to make sure it is not created in the HDR process.
Does anyone have any tips how to avoid this problem?
Cheers Brian



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Problems with Noise in Dark Areas
« on: October 14, 2012, 03:59:27 AM »

Kernuak

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Re: Problems with Noise in Dark Areas
« Reply #1 on: October 14, 2012, 04:25:26 AM »
One of the side effects of HDR, is that the processing can add noise, as it is pushing the exposure in some areas. It is particualrly noticeable if you shoot a silhouette. To be honest, I don't really see the need for HDR when shooting a silhouette, as you would normally just expose for the background and leave the foreground completely blocked out. Also, with such large contrast differences in the transition areas, HDR results in unsightly haloes.
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bjd

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Re: Problems with Noise in Dark Areas
« Reply #2 on: October 14, 2012, 04:59:07 AM »
One of the side effects of HDR, is that the processing can add noise, as it is pushing the exposure in some areas. It is particualrly noticeable if you shoot a silhouette. To be honest, I don't really see the need for HDR when shooting a silhouette, as you would normally just expose for the background and leave the foreground completely blocked out. Also, with such large contrast differences in the transition areas, HDR results in unsightly haloes.
You know, posts like that "usually" upset me, as in "dont do what you are trying to do"! >:(
But I took your advice and from a single shot I managed to achieve what I wanted without any HDR at all,
just with the normal tools in Lightroom. So obviously I'm not upset.
And here's the result. Biggest difference is the almost complete lack of noise and Halo around the tree.
I had 5 bracketed shots so basically went the HDR route without trying alternatives first. 
Thanks very much for the idea.

CHeers Brian

Kernuak

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Re: Problems with Noise in Dark Areas
« Reply #3 on: October 14, 2012, 07:49:47 AM »
One of the side effects of HDR, is that the processing can add noise, as it is pushing the exposure in some areas. It is particualrly noticeable if you shoot a silhouette. To be honest, I don't really see the need for HDR when shooting a silhouette, as you would normally just expose for the background and leave the foreground completely blocked out. Also, with such large contrast differences in the transition areas, HDR results in unsightly haloes.
You know, posts like that "usually" upset me, as in "dont do what you are trying to do"! >:(
But I took your advice and from a single shot I managed to achieve what I wanted without any HDR at all,
just with the normal tools in Lightroom. So obviously I'm not upset.
And here's the result. Biggest difference is the almost complete lack of noise and Halo around the tree.
I had 5 bracketed shots so basically went the HDR route without trying alternatives first. 
Thanks very much for the idea.

CHeers Brian
"Usually", because most of the stuff on the web with high contrast transition areas is that way and Photomatix is probably the worst offender. Granted, there are people that can process in such a way that they can often be avoided, but they certainly seem to be in the minority and it takes painstaking work and/or practice. Those that have perfected the processing over long periods of practice can probably achieve the processing quite quickly in individual images. In this case, as you see, HDR wasn't needed and that is the biggest problem with HDR. I suppose it is like many things in vogue, they are often overused to the point that even sensible people start to think it's the only way. HDR is a useful tool, like anything else, but I would urge people to try other alternatives first, it gives much more natural results and avoids the risk of adding in unwanted elements that you can get, if not careful, when you do any sort of large scale processing. Sometimes heavy processing is wanted for a certain look, as it can be very dramatic, but it depends on the look you are after and haloes never look good, even on an intended heavily processed look.
I'm glad my comments helped, insuating you didn't know what you were doing wasn't intentional and having seen a lot of HDR on the web that is painful to look at, I'm a bit sensitive about HDR being used unnecessarily. Btw, it looks much better now.
« Last Edit: October 14, 2012, 07:52:48 AM by Kernuak »
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bjd

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Re: Problems with Noise in Dark Areas
« Reply #4 on: October 14, 2012, 08:05:17 AM »
>>insuating you didn't know what you were doing wasn't intentional

I didn't understand it that way. No Problems.

Yes I think it does look far better too.

wsheldon

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Re: Problems with Noise in Dark Areas
« Reply #5 on: October 14, 2012, 10:02:30 AM »
Issues of HDR aside, I really love the "mood" of your final image. Very nice. The experience you relate here is a great reminder of why shooting multiple exposures and trying different techniques in post is so powerful. You may have started out to use HDR for a challenging exposure situation but had the raw images to go another way in response to feedback. Thanks for sharing.
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blaydese

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Re: Problems with Noise in Dark Areas
« Reply #6 on: October 15, 2012, 04:17:10 AM »
Agree, great job once you found
the problem and worked it out.

I agree, I too have spent almost 30 min working
on one picture, then BAM, I just stop and take a break. 
Come back and use a preset or two and TADA
picture looks great!

Good luck in the future, stick with it and enjoy your hobby,
I too find it better when I just take my time.

Great picture by the way, really like the green patch.

Peace! 8)

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Re: Problems with Noise in Dark Areas
« Reply #6 on: October 15, 2012, 04:17:10 AM »

bjd

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Re: Problems with Noise in Dark Areas
« Reply #7 on: October 16, 2012, 11:57:28 AM »
Issues of HDR aside, I really love the "mood" of your final image. Very nice. The experience you relate here is a great reminder of why shooting multiple exposures and trying different techniques in post is so powerful. You may have started out to use HDR for a challenging exposure situation but had the raw images to go another way in response to feedback. Thanks for sharing.
Thanks. Here's another one that turned out good (IMHO) without HDR.
On here it looks far too dark though, this is still nothing like what it looks like under LR on my monitor.

I hope I don't get banned from this Forum because of this..(I Mean posting non-HDR shots in a HDR Forum).... :-\


Anyway, I'll still be stuck with the noise problem next time I try HDR.


« Last Edit: October 16, 2012, 01:55:54 PM by bjd »

blaydese

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Re: Problems with Noise in Dark Areas
« Reply #8 on: October 17, 2012, 04:29:39 AM »
I hope I don't get banned from this Forum because of this..(I Mean posting non-HDR shots in a HDR Forum).... :-\


Anyway, I'll still be stuck with the noise problem next time I try HDR.

Oh, that's done it now, we'll pull your finger nails out
and soak your hands in hot sauce!  How dare you post
non HDR shots!  ... Ha ha Just kidding !  Nice picture,
I don't think it's dark at all, imagine that shot blown
up to 24" X 36 and framed, it'd be simply epic.

There is nothing wrong with dark if that is the mood of
the picture.

Dark picture of a clown at a circus, is not cool. ???
clown are bright and cheery, well unless you are going for
something sinister.   :o


Keep working on the HDR, it'll come around,
we're all still learing, and reember it's supposed
to be.....  FUN!   ;D

Peace! 8)

bjd

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Re: Problems with Noise in Dark Areas
« Reply #9 on: October 17, 2012, 03:04:28 PM »
OK, well maybe its not too dark, maybe the dynamic range isn't large enough.
Hmm I'll have a look at ways to increase the DR I think.

>>FUN!   ;D

Now you tell me!

bvukich

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Re: Problems with Noise in Dark Areas
« Reply #10 on: October 17, 2012, 03:13:08 PM »
I hope I don't get banned from this Forum because of this..(I Mean posting non-HDR shots in a HDR Forum).... :-\

Oh boy...  let me go grab the ban-hammer...

 ;D

sublime LightWorks

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Re: Problems with Noise in Dark Areas
« Reply #11 on: October 17, 2012, 03:34:54 PM »
In a web course on Kelby, Matt discusses the noise issue.  It stems from not shooting the upper exposures (overexposed) images high enough to get all the detail in the shadows.  That becomes noise in the HDR resulting image.  He illustrates this in a few examples.

By exposing on the high end (overexposed) enough to move the histogram off the left edge completely, you insure that you got all the shadow detail and thus reduce any noise in the HDR by a great margin.

You might want to give this try.  There was also a recent webinar on the Topaz site on reducing and controlling noise in HDR photos.




preppyak

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Re: Problems with Noise in Dark Areas
« Reply #12 on: October 17, 2012, 03:37:39 PM »
But I took your advice and from a single shot I managed to achieve what I wanted without any HDR at all,
just with the normal tools in Lightroom. So obviously I'm not upset.

And here's the result. Biggest difference is the almost complete lack of noise and Halo around the tree.
Nice shot.

I tend to find I do the same thing...I'll bracket 5 shots, try the HDR, and end up with too much noise or just not a nice blend, so I'll go back use just a single exposure in PS or Photomatix, and I tend to like the results much more. It also results in a much more natural image; if that tree in the foreground was brighter, it would make it look fake, since my mind knows it can't be that bright in the shadows.

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Re: Problems with Noise in Dark Areas
« Reply #12 on: October 17, 2012, 03:37:39 PM »

wickidwombat

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Re: Problems with Noise in Dark Areas
« Reply #13 on: October 18, 2012, 01:55:01 AM »
topaz denoise works really well since you can control different levels of noise reduction for shadows highlights and colours try out the 30 day free trial and see what you think
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bjd

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Re: Problems with Noise in Dark Areas
« Reply #14 on: October 21, 2012, 11:26:13 AM »
topaz denoise works really well since you can control different levels of noise reduction for shadows highlights and colours try out the 30 day free trial and see what you think
Hi,
thanks for the tip, seems like they are having a sale at the moment, 30% off I think.

Up till now I am not too impressed with the results. In my experience, too much loss of sharpness coupled to the noise reduction. But that is at 100% crop, maybe I am expecting too much at that level and I just need to look at the end results at normal viewing distance.
I'm going to take a look for some tutorials too.

Cheers Brian

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Re: Problems with Noise in Dark Areas
« Reply #14 on: October 21, 2012, 11:26:13 AM »