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Author Topic: DR: Getting maximum information from a single exposure  (Read 4173 times)
ErikKaffehr
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« on: October 06, 2012, 01:33:57 AM »
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Hi

I would just recommend this link (by leuallen) : https://docs.google.com/open?id=0B8ETvhCd81aFMTUyMTU4OTctZGQxZS00NTBmLWE5MDgtMDIwNWM1ODA3M2I4

Best regards
Erik
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Mark D Segal
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« Reply #1 on: October 06, 2012, 01:42:27 AM »
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Erik,

I'm confused. Looks to me like that set of instructions is carried out in LR. What is SNS? Where does one get it? What makes it different and better than LR or PS for masking? How does one actually use it in comparison with how one uses brushes in LR and PS for the same purpose? Grateful if you could explain the context a bit.
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Mark D Segal (formerly MarkDS)
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stamper
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« Reply #2 on: October 06, 2012, 03:27:37 AM »
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In my limited knowledge of image processing it is perfectly possible to get maximum information from a single exposure - especially with LR4 - that will satisfy most photographers without going down the HDR route. Over exposure of three stops and underexposure of three can be rescued to provide a very good image that should mean the use of HR is only for the more zealous of processing stalwarts. Saves the expense of buying HDR programs
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ErikKaffehr
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« Reply #3 on: October 06, 2012, 04:49:18 AM »
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Hi,

Sorry for the confusion, mea culpa.

SNS HDR is a a program intended for processing HDR images. Normally you would blend several exposures. What we did here was to make a few different developments of a raw image and tone blend in SNS HDR. So it is a straightforward image from a single exposure that is processed with HDR tools.

The article that started the discussion is this one: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/61-hdr-tone-mapping-on-ordinary-image

Larry took my original image and processed it using SNS HDR:s set of tools instead and he described the process in the PDF.

The new 1012 processing pipeline in Lightroom can do similar things, if extensive highlight compression is used.

So the whole idea was to demonstrate that a single exposure can have a lot of DR, but it needs some kind of tone mapping to turn it into a dramatic image.

Best regards
Erik


Erik,

I'm confused. Looks to me like that set of instructions is carried out in LR. What is SNS? Where does one get it? What makes it different and better than LR or PS for masking? How does one actually use it in comparison with how one uses brushes in LR and PS for the same purpose? Grateful if you could explain the context a bit.
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ErikKaffehr
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« Reply #4 on: October 06, 2012, 04:57:06 AM »
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Hi,

This is not about rescuing images but about mapping a wide dynamic range into what can be shown on screen, a process called "tone mapping".

When this article was written we still had LR3. LR4 has some tone mapping capability built in.

The enclosed images are:

- "Straight" image processed in Lr4
- Extensively processed image in LR4 followed by darkening sky in Photoshop CS5 using multiply and a luminousity mask.

Best regards
Erik



In my limited knowledge of image processing it is perfectly possible to get maximum information from a single exposure - especially with LR4 - that will satisfy most photographers without going down the HDR route. Over exposure of three stops and underexposure of three can be rescued to provide a very good image that should mean the use of HR is only for the more zealous of processing stalwarts. Saves the expense of buying HDR programs
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BartvanderWolf
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« Reply #5 on: October 06, 2012, 05:15:23 AM »
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Erik,

I'm confused. Looks to me like that set of instructions is carried out in LR. What is SNS? Where does one get it? What makes it different and better than LR or PS for masking? How does one actually use it in comparison with how one uses brushes in LR and PS for the same purpose? Grateful if you could explain the context a bit.

Hi Mark,

In addition to Erik's response, SNS-HDR is (arguably) the best (HDR) tonemapping application available (for Windows, although it apparently runs fine under Parallels and the like on a Mac). Even though the LR/ACR's PV2012 tonemapping has closed some of the gap, SNS-HDR still offers a feature set that's hard to find anywhere else. It also reads .EXR files, the most universal HDR fileformat for photography related scenes.

Especially when dealing with 'impossible' scenarios, like shooting straight into the sun or when shooting interiors with a brightly lit outside view, the only solution is to shoot multiple exposures, which SNS-HDR handles gracefully. LR would require a roundtrip to Photoshop to create a huge HDR TIFF, where SNS-HDR just takes the individual exposures and interactively or in batch produces very natural looking output.

What Erik wanted to highlight is that the application also can work miracles on a single file, although it's limited by what the image has to offer (e.g. noisy shadows or blown highlights). There the difference with e.g. LR's PV2012 becomes smaller, although SNS-HDR offers special tonemapping features not found in LR and its realtime updating preview makes for a very creative and interactive use of the controls.

Cheers,
Bart


P.S. I've added an example of tonemapping of an HDR scene detail, where I've tried to match the look of the LR tonemapping (but without the posterization artifacts)
« Last Edit: October 06, 2012, 06:37:55 AM by BartvanderWolf » Logged
stamper
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« Reply #6 on: October 06, 2012, 05:28:06 AM »
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Quote Erik

This is not about rescuing images but about mapping a wide dynamic range into what can be shown on screen, a process called "tone mapping"

Unquote



In reality tone mapping is about rescuing images. Grin
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BartvanderWolf
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« Reply #7 on: October 06, 2012, 05:30:12 AM »
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In my limited knowledge of image processing it is perfectly possible to get maximum information from a single exposure - especially with LR4 - that will satisfy most photographers without going down the HDR route. Over exposure of three stops and underexposure of three can be rescued to provide a very good image that should mean the use of HR is only for the more zealous of processing stalwarts. Saves the expense of buying HDR programs

Hi,

One would be tempted to think so, untill offered the power SNS-HDR has to offer for exercising much better control over the tonemapping process. While it already does magic on a single file, making multiple conversions from a single Raw does offer advantages. One can for example use more agressive noise reduction on the shadow optimized version of the file, and even do that with a different Whitebalance, should there be a benefit to doing so (e.g. remove noise and overly blue shadows).

In addition to offering the capability to massage the tonecurve in detail, SNS-HDR does so in a very photorealistic way (e.g. shadows do not get oversaturated, although one could make them so), and virtually halo free.

Seeing is believing, that's why everybody who has tried it seriously is so enthusiastic.

Cheers,
Bart
« Last Edit: October 06, 2012, 04:10:51 PM by BartvanderWolf » Logged
ErikKaffehr
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« Reply #8 on: October 06, 2012, 06:33:26 AM »
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Hi,

I don't agree. Let's take a typical example. So you are shooting in a mediaeval church with small windows and mosaic. The interior is dark and the church is surrounded by well illuminated landscape. Such an image could easily hold a contrast ratio of 1:30000. You can shoot several exposures and combine, but without tone mapping the image would be very flat an boring. A correct tone mapping would have a good gradient in the highlights, in the darks and in the mid tones.

Best regards
Erik


Quote Erik

This is not about rescuing images but about mapping a wide dynamic range into what can be shown on screen, a process called "tone mapping"

Unquote



In reality tone mapping is about rescuing images. Grin
« Last Edit: October 06, 2012, 07:49:55 AM by ErikKaffehr » Logged

RFPhotography
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« Reply #9 on: October 06, 2012, 06:40:54 AM »
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SNS is a very nice piece of software.  I reviewed it for my series on HDR applications a couple of years ago.  I would expect it to be even better now.  Unless things have changes, it's more like Enfuse as it didn't take things into a 32 bit floating point space.  I should take a look at the newest version to see the improvements.

Bart, the issue of the huge 32 bit TIFF files may be dealt with in the new DNG spec which allow it to use 32 bit float precision.  Now all we need are ways to create 32 bit DNGs to see how file sizes compare.  But Adobe has nothing to say about that yet.
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BartvanderWolf
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« Reply #10 on: October 06, 2012, 07:25:42 AM »
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SNS is a very nice piece of software.  I reviewed it for my series on HDR applications a couple of years ago.  I would expect it to be even better now.  Unless things have changes, it's more like Enfuse as it didn't take things into a 32 bit floating point space.  I should take a look at the newest version to see the improvements.

Hi Bob,

I don't know which version you tried, but the program has indeed improved since. Masking layers were added, and the overall quality has improved in specific areas. Expected in a month, or two, are additional manual control of ghosting artifacts, and Chromatic aberration reduction (for those who do the Raw conversion directly in SNS-HDR). The upgrade to version 2.0 is apparently free for current users. SNS-HDR indeed uses an Exposure blending approach which often delivers more natural tonemapped results, rather than pure HDR creation, camera response curve determination, and subsequent tonemapping.

Quote
Bart, the issue of the huge 32 bit TIFF files may be dealt with in the new DNG spec which allow it to use 32 bit float precision.  Now all we need are ways to create 32 bit DNGs to see how file sizes compare.  But Adobe has nothing to say about that yet.

I know they have added that to the DNG specification, but it would be much more useful to allow importing of .EXR files, the open industry standard for photographical HDR images (which also offers various compression modes, both lossless and lossy). 32-b/ch TIFFs, or a DNG wrapper for them, will still produce huge files, due to an inefficient (for specifically HDR photography) choice of universal floating point numbers. 32-b/ch TIFF has to be flexible because it will also be used for other purposes than specifically photographic images (e.g. CGI, or numerical data layers), but that also makes it less efficient as a basis for our specific photographic needs.

Cheers,
Bart
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RFPhotography
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« Reply #11 on: October 06, 2012, 07:56:35 AM »
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I completely agree, Bart about LR being able to handle .exr and .hdr files and have been ststing so for some time.  Sadly, Adobe doesn't really seem to listen except whenit suits them so I'm not overly optimistic.

It was an early versionof SNS that I reviewed.  The creator of the program incorporated a couple ideasI suggested in my review and through email exchanges.  I should take another look at it.  I agree that it could render very natural results.  Back then it wasn't up to the task of higher volume, quick turnaround commercial work but was a really good option for personal work.
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leuallen
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« Reply #12 on: October 06, 2012, 09:00:24 AM »
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Well, I really like SNS. A woman purchased an HDR image of a sunrise and it needed to be printed at a larger size. It was originally processed in another program and looked OK, that is, until I reprocessed in SNS. There was quite a difference: the original had a funky color banding around the sun. That was fixed in SNS to give a natural looking result. Overall, much better. The result was a natural looking image, not the overprocessed stuff you often see.

As to my original article. I found that it is not really necessary to use two exposures, just take the image into SNS. All of the goodness is still there. At least that is what I remember from subsequent experiments. I have been out of the loop for the last year due to family illness and have not done much work so things may have changed. We have a tendency to overcomplicate things at times when a simpler approach is just as effective. The P2012 process will probably give similar results for highlights and shadows but it was not available then. What the P2012 process is missing is the control that is available by the use of masks. The sliders in SNS do pretty much as you would expect in plain understandable terms. Many of the other programs that I tried used arcane terms so you did not know what they did without lots of experimentation.

Larry
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Mark D Segal
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« Reply #13 on: October 06, 2012, 03:52:42 PM »
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Hi Eric and Bart,

Thanks very much for the clarifications. Probably worth checking out. I'm on Mac now but have Parallels on one of my computers.
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Mark D Segal (formerly MarkDS)
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BigBadWolfie
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« Reply #14 on: October 06, 2012, 08:03:17 PM »
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I'm a bit confused.  Don't other HDR programs like Nik's allow you to tone map single exposures? I guess the question is how does SNS compare?
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BartvanderWolf
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« Reply #15 on: October 06, 2012, 08:05:37 PM »
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The P2012 process will probably give similar results for highlights and shadows but it was not available then. What the P2012 process is missing is the control that is available by the use of masks.

Hi Larry,

While I agree that PV2012 has reduced the gap, SNS-HDR still allows considerably finer control over the tonemapping process (yet with understandable control terms, as you said).

The main issue with SNS-HDR is that it make it too easy to get good results! I often wonder, is that all it takes (sometimes just two or three slider adjustments) to improve my image to what I wanted to achieve? It can be an underwhelming experience. Achieving quality is really that easy (although SNS-HDR allows to tweak to much more than good enough, at diminishing returns of the time invested).

One of the great things for advanced tweaking is that it allows to separate the overall processing from the highlights processing, even before applying masks which can specifically target anything that's required. Also the possibility to +/- adjust microdetail per color range, which e.g. allows to spare blue skies from the boost given to other ranges, is very useful.

Cheers,
Bart
 
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BartvanderWolf
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« Reply #16 on: October 06, 2012, 08:22:44 PM »
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I'm a bit confused.  Don't other HDR programs like Nik's allow you to tone map single exposures? I guess the question is how does SNS compare?

Hi,

Well, that's exactly how SNS-HDR differs from the rest. Even a seasoned HDR photographer and acclaimed Visual Effects Artist as Christian Bloch was almost gobsmacked at what SNS-HDR had to offer when he reviewed it for his upcoming (December 2012) book update.

Cheers,
Bart
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BigBadWolfie
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« Reply #17 on: October 07, 2012, 05:02:46 AM »
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Hi,

Well, that's exactly how SNS-HDR differs from the rest. Even a seasoned HDR photographer and acclaimed Visual Effects Artist as Christian Bloch was almost gobsmacked at what SNS-HDR had to offer when he reviewed it for his upcoming (December 2012) book update.

Cheers,
Bart
I think you missed my point.  My point was that I failed to see how SNS differed from other HDR programs and the review you linked doesn't answer my question.  Obviously there are going to be things that one program/plugin does better than the other, but isn't SNS just another HDR program (i.e. an alternative to say Photomatrix and Nik's HDR Efex Pro 2)?  What makes it special?
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BartvanderWolf
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« Reply #18 on: October 07, 2012, 06:21:47 AM »
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What makes it special?

The quality of the tonemapping, and the quick way of getting there (once the files are loaded). Just look at the example crop I posted a few messages earlier, Lightroom (4.1 at that time) was not able to render the highlights without posterization and introduction of strange colors. With SNS-HDR the most time I needed was to approximate the Lightroom look for easier comparison. Otherwise, not having to fight artifacts, I could have produced many different looks which might have suited my vision even better.

SNS-HDR does allow to spend more time and get even more tweaks in, just like with other programs (although more of a need with some of those), but how useful (or even necessary) that is depends more on the artistic vision of the user than the shortcomings of the tonemapping. It also allows to tweak things that are much harder to achieve, if at all possible, in other applications (and I have tried almost all of them since the early days of HDR).

Cheers,
Bart
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RFPhotography
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« Reply #19 on: October 07, 2012, 06:32:08 AM »
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It is a competitor to those others.  Keep in mind that 'better' is subjetive.  If you're into the really hyperprocessed 'HDR look' then SNS may not be your cup of tea, although it can take youin that direction if you want.  It's different in that, as mentioned already, it doesn't take images into a 32 bit space.  It also, for some who have difficulty doing so with other HDR programs, tends to be easier to get a more 'natural' looking result. In the vesion I worked with, it doesn't have the tendency of some othee programs to oversaturate colours nor to introduce colour casts as a result, as some others can do.  Best bet would be to try it out and see for yourself how it's different and determine whether you think it's better or not.
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