different tonality from HDR source

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different tonality from HDR source

Postby Erik Krause » Fri Oct 12, 2012 7:46 pm

Hello,

using HDR images (.exr or .hdr format) merged in photoshop CS6 or photomatix as source for SNS-HDR lite give a completely different tonality from merging LDR images directly in SNS-HDR lite using the very same settings.

I wanted to use the deghosting in photoshop and was really happy to discover that SNS-HDR can also read .exr and .hdr files. However, the colors are darker and way more saturated if I do so compared to the result I get when I feed the images directly to SNS-HDR. The source images are converted from raw in ACR using AdobeRGB color space, but converting them to sRGB color space doesn't help.

To cross-check this isn't a photoshop problem I did the merge to HDR step with photomatix and with PTGui with same results. I also tried -srgb option to no avail.

best regards
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Re: different tonality from HDR source

Postby Sebastian Nibisz » Fri Oct 12, 2012 8:42 pm

You must set the correct exposure parameter of the image in the exr/hdr file. You can adjust the exposure parameter in Photoshop.

Here is examples OpenEXR images displayed in Photoshop.

corrrect (0ev)
Image

incorrect (-4ev)
Image

incorrect (+4ev)
Image
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Re: different tonality from HDR source

Postby Erik Krause » Fri Oct 12, 2012 9:34 pm

Thanks for the hint, however, it's mainly the colors that are wrong:
_MG_2423l_SNS.jpg
images merged in SNS
_MG_2423l_SNS.jpg (47.25 KiB) Viewed 12373 times

Untitled_HDR2-HDR(1)_Natural.jpg
HDR source merged in photoshop
Untitled_HDR2-HDR(1)_Natural.jpg (46.2 KiB) Viewed 12373 times


Only to be clear: Both images are processed in SNS-HDR lite with the very same settings. One diretly from 16 bit TIFF images, one from a .exr image merged in photoshop.
In addition the version from .exr has less shadow details...

BTW.: I adjusted the exposure of the EXR to +2 in photoshop. The SNS result looks pretty much the same like the exposure=0 version.
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Re: different tonality from HDR source

Postby mistermonday » Sat Oct 13, 2012 7:25 pm

Erik, that should not surprise you.
First of all, every HDR application (Photoshop Merge to HDR, Photomatix, PhotoEngine, Nik, SNS-HDR) will produce a merged result which is different from every other application. You can notice differences in tone, color, saturation, and detail. There is no standard for merging LDR source files. Every HDR app has its own set of algorithms, its "secret recipe". Some programs are better than others regarding which distortion occur.
Secondly, when SNS performs tonemapping prior to displaying a merged image and the results will be very different from an application which merges source images but which expects the user to perform much of the tonemapping for visual effect.
Thirdly, any time you open a RAW file in Photoshop ACR, or Lightroom, or the camera manufacturers supplied viewer/editor, the RAW data is interpreted so it can be visualized. Each application will automatically apply a certain amount of brightness and contrast adjustment, thereby modifying the data. Sometimes this will clip weak shadows or fragile highlights so what you end up feeding into a HDR application is different from unmodified RAW source files. It's a bit like Heisenberg's Uncertainty Principle.
While Photoshop is a super fantastic image editing program, and has the best Alignment and De-ghosting, almost every HDR enthusiast on any HDR forum will agree that PS (CS5 and CS6) is the worst application of any when it comes to HDR merge and tonemapping.
Cheers, Murray
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Re: different tonality from HDR source

Postby Erik Krause » Sat Oct 13, 2012 8:26 pm

It looks like I have to accept the first point. I got fooled by CS6 merged HDR and photomatix merged HDR giving the same result after tonemapping in SNS. I did another test using Picturenaut, and the result was totally different (worse).

As for the second point: I use SNS for both versions. I wouldn't complain because the result from some other tonemapper would differ from SNS, since I want to use SNS because the result is different - much better in fact.

The third point doesn't apply, since I don't use raws in SNS, I use the same 16 bit TIFFs in both cases.

I wanted to combine the superb de-ghosting of photoshop and the superb tonemapping of SNS. Unfortunately the SNS tonemapping isn't as good for single HDR source files as it is for multiple TIFFs. I shoot for panoramas. My hope was that I could use PS de-ghosting on single problematic frames. However, I won't run all images through the PS process if this gives me worse results - and I can't stitch a panorama with single images in it that look so different to the rest.

So my only hope is, that SNS will have a de-ghosting soon, that equals those of photoshop or photomatix.

Thanks for your effort anyway.
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Re: different tonality from HDR source

Postby Sebastian Nibisz » Sat Oct 13, 2012 9:24 pm

The second image is not bad. If you want a brighter shadows in this image then you increase the exposure by 1 or 2ev in the EXR file (in Photoshop).
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Re: different tonality from HDR source

Postby Erik Krause » Wed Oct 24, 2012 8:31 pm

I did some further testing with different source images. 16 bit TIFFs from a night time shot merged to EXR in photomatixcl turn out completely black-and-white after tonemapping in SNS-HDR lite. If I load the EXR in photoshop it looks black. If I adjust the exposure (in Ps) that it looks reasonable and save it such, SNS creates a relatively good looking result but with a white balance which is way off the source images. For daytime shots it is not so extreme, but the results vary in an unpredictable way, possibly related to the absolute EV of the source images.
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Re: different tonality from HDR source

Postby lisieckima » Sun Nov 04, 2012 9:09 pm

After a few months of testing I have to admit that there is no perfect solution for HDR processing. All of the software applications have some deficiencies that still need addressing. Most of them are the following:

* problems with proper deghosting
* noise increase
* colors wash-out
* change in tonality
* decrease in image sharpness
* artifacts (especially visible on images where trees with leaves meet the sky area)
* 'dirty whites'
* halo effects

I have tested the following applications with different combinations of hdr file generation and tone mapping: SNS-HDR, Photoshop CS5 Pro, Photomatix, Zero Noise, PhotoAcute, FDR Tools, HDRExpose, Oloneo, Dynamic Photo HDR, Akvis, HDR Photo Studio, Dynamic Photo HDR.

At this moment I'm using the following solution which is the combination of different applications that seems to give one of the best results:

1) DxO Optics Pro - used for lens corrections only, including chromatic aberration, and saving different exposures to DNG format. It's better from Lightroom regarding chromatic aberration removal.

2) Photomatix - used for 32bit file generation (exr) - this app seems to give the best results in tonality; what's most important - I deghost the image using MANUAL mode only - using the automatic mode reduces the image quality in terms of sharpness and noise and makes it useless to me.

3) SNS-HDR - the best tool for tone-mapping. There's no better tool if you are interested in realistic results. The masks implemented in the software are very helpful to reduce the halos that are mostly visible in the skies. Masking the sky and reducing Microcontrast and Microdetails removes the halo completely. Reducing the Sharpening levels below zero also helps to smooth out some noise in areas where deghosting has been performed.

4) Photoshop - finishing software. I use it especially to remove the artifacts that appear in problematic areas like leaves on the sky.

I believe that at this moment it's really hard to find a better solution. But I'm still searching and testing different apps. SNS-HDR is one of the best discoveries in my toolset.
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Re: different tonality from HDR source

Postby Andras Jacso » Thu Jun 06, 2013 7:38 am

lisieckima:

I'd like to know about your method you've mentioned earlier:

"The masks implemented in the software are very helpful to reduce the halos that are mostly visible in the skies. Masking the sky and reducing Microcontrast and Microdetails removes the halo completely."

I got somekind of a haze around the sun as a result of tonemapping 3 bracketed shots 2 stops apart (-2,0,+2EV).
Could you explane it in detail pls?

You can take a look of my issue here:
viewtopic.php?f=7&t=1753&p=2931#p2931

Regards, Andras
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