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03-09-2015, 04:48 PM   #1
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HDRMerge

I just posted this here, but then figured it's worthy (imo) of it's own thread...

If you guys are interested in merging bracketed shots, but being able to do all the rest of your edits separately (in your raw editor), I highly recommend you try this app: HDRMerge. It's not perfect yet (and there is a known bug I encounter sometimes where if you use say five bracketed shots, you may have to remove one of the dark images or else the image doesn't turn up...), but overall, it rocks...

As the above linked to about page reveals, you'll need a recent version of Lightroom, or Rawtherapee (my raw editor of choice) to get the DNG 1.4 support (for retaining as much dynamic range as possible)... I used to sort-of do this with Luminance HDR and save the tif before tone mapping, but HDRMerge is much faster and Luminance still does some adjustments that this app doesn't...

edit - clarification based on Steve's reply, this app takes as many raw images as you feed it and works directly on the raw data then churns out one digital negative (DNG) file from them...

edit: image example removed for now bc it was bugging me and Steve has now provided an example below...


Last edited by todd; 03-30-2015 at 05:15 PM. Reason: removed photo example
03-09-2015, 06:05 PM   #2
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QuoteOriginally posted by todd Quote
If you guys are interested in merging bracketed shots, but being able to do all the rest of your edits separately (in your raw editor), I highly recommend you try this app: HDR Merge.
Thanks. I am going to have to give this one a try. Is it able to do the merge in a broad gamut (e.g. ProPhoto RGB)? I have used PaintShop Pro for merges, but it only works in sRGB


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03-09-2015, 06:12 PM   #3
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QuoteOriginally posted by stevebrot Quote
Thanks. I am going to have to give this one a try. Is it able to do the merge in a broad gamut (e.g. ProPhoto RGB)? I have used PaintShop Pro for merges, but it only works in sRGB


Steve
...answered my own question. HDRMerge outputs as DNG. Yes the merge is done directly on the RAW data. Woo! Hoo!

Steve
03-09-2015, 06:24 PM   #4
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You can do pretty much the same with PS and LR - use the HDR function of PS, then choose 'Edit in Lightroom' and you get a 32 bit file that you can edit in LR.

03-09-2015, 06:40 PM   #5
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QuoteOriginally posted by FantasticMrFox Quote
You can do pretty much the same with PS and LR - use the HDR function of PS, then choose 'Edit in Lightroom' and you get a 32 bit file that you can edit in LR.
Cool thanks for mentioning it... If I were using LR, I'd want to compare the two...
03-09-2015, 06:41 PM - 1 Like   #6
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QuoteOriginally posted by FantasticMrFox Quote
You can do pretty much the same with PS and LR
Unless, like me, a person is too cheap to buy PS.


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03-09-2015, 06:56 PM   #7
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To be honest, I tried it once and wasn't too impressed by the results. In theory it should give you a vastly increased dynamic range to work with in LR without encountering the usual issues (noise when pulling up the shadows etc.), but when I used a normal one shot DNG of the same scene and did the exact same edit, I didn't see any of these benefits in the HDR. Instead I got a very nasty halo around one object in the image.

Now I might be partly at fault here because I have very little knowledge of proper HDR processing AND I shot the sequence handheld and used PS's align feature. I'd be glad if anyone who has some more extensive experience at HDR would give that workflow a try and report his/her results here
03-09-2015, 07:13 PM   #8
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QuoteOriginally posted by FantasticMrFox Quote
vastly increased
I don't know about 'vastly', but you will definitely notice increase if you try HDRMerge... My above example wasn't the best because the +4 was almost totally blown out... When I have more time I will work up a little comparison/example for this thread..


Last edited by todd; 03-09-2015 at 07:33 PM.
03-09-2015, 10:47 PM   #9
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Apparently LR6 will have HDR merge built in.
03-30-2015, 04:24 PM   #10
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I spent some time fiddling with HDRMerge today, much more time than I would have preferred if the truth be known. Part of that was learning curve and to be honest, I am not sure yet just what to expect from each of the contributing files. I finally gave up on the editing and processed a 5-step, 2-stop bracketed series. I then imported and processed the resulting DNG as if it were any other RAW file, though with the intent to open up, brighten, and pull detail out of the shadows. Below are the results in comparison with a single shot of the same subject processed with the same intent.



Overall, I would give the nod to HDRMerge. The merged image has much better rendering of the sky and the histogram (not shown here) had much more data in the mid-tones than on the single capture. Overall, I would say that the shadows of the merged image are more open with greater detail and better tonality. That being said, here are a few notes:
  • I was surprised to see color shifts in the merged image. I did a manual white balance, but was unable to match the colors of the single shot using white balance alone.
  • The merged file was easier to work with overall for this type of subject
  • There was an amplification of axial lateral CA that fortunately was easily cleaned
  • The contribution of the +2 image to bring the shadows up was much less than I expected
I don't know if this will spur further discussion, but it would be nice.


Steve

Last edited by stevebrot; 03-31-2015 at 07:36 AM.
03-30-2015, 04:49 PM   #11
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QuoteOriginally posted by stevebrot Quote
I was surprised to see color shifts in the merged image.
Not sure if I've seen this, unless you're talking highlights.. In that regard based on a github page where I posted some DNG's to help the developer fix the blank image issue, he responded yesterday that he "pushed some new commits to the develop branch that should fix the problem with the black images and improve the color tints in the blown out areas." So maybe that will help when he releases 0.5.1...

QuoteOriginally posted by stevebrot Quote
The merged file was easier to work with overall for this type of subject
Yes, this is what I find too, and that's even with mostly working with hand held stuff... and I really appreciate how fast it is... and it rarely works out poorly enough that I can't fix it...

QuoteOriginally posted by stevebrot Quote
There was an amplification of axial CA that fortunately was easily cleaned
Is that from the app, or from the +2?

QuoteOriginally posted by stevebrot Quote
The contribution of the +2 image to bring the shadows up was much less than I expected
Yeah, I think it's due to the general theory behind the app (from the about page) "HDRMerge merges raw images directly, without development. The advantages are that it is very fast, requires little to none input from the user, and can be very optimistic on which pixels are the best ones. In fact, it can safely assume a linear response function of the camera. The resulting image then consists of the most exposed pixels from the input images that are not saturated. This ensures the lowest possible level of noise and highest detail in the output image. This is inspired in what Guillermo Luijk implemented with Zero Noise."
03-30-2015, 04:56 PM   #12
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worth the effort...top image is much better.......I know next to nothing what you guys are talking about.......
03-30-2015, 06:10 PM   #13
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QuoteOriginally posted by todd Quote
Is that from the app, or from the +2?
Av mode...
03-30-2015, 06:14 PM   #14
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QuoteOriginally posted by stevebrot Quote
Av mode...
I mean the amplification... Do you think the app amplified it, or is it from one of the files? (If your answer still applies, then I just don't get it)...
03-30-2015, 09:00 PM   #15
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QuoteOriginally posted by todd Quote
I mean the amplification... Do you think the app amplified it, or is it from one of the files? (If your answer still applies, then I just don't get it)...
I believe that HDRMerge has edge sensing routines that amplified the ~1-2 pixel axial lateral CA that was present on the originals to 3-4 pixel on the merged file where it was readily evident even at moderate enlargement.

As for "Av" mode...axial CA varies by aperture.

Edit: Sorry for the confusion. I wrote axial, but meant lateral.


Steve

Last edited by stevebrot; 03-31-2015 at 07:38 AM.
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