Image & Video Galleries > HDR - High Dynamic Range

Problems with Noise in Dark Areas

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bjd:
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


Kernuak:
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.

bjd:

--- Quote from: Kernuak 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.

--- End quote ---
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:

--- Quote from: bjd on October 14, 2012, 04:59:07 AM ---
--- Quote from: Kernuak 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.

--- End quote ---
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

--- End quote ---
"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.

bjd:
>>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.

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