Author Topic: Dual ISO - massive dynamic range improvement (dual_iso.mo)  (Read 1546171 times)

DeafEyeJedi

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2375 on: February 17, 2015, 12:02:33 AM »
Got it @Audionut -- Actually saw that thread and at first I though it was more Dual-ISO related but after your pointers I'll try reading the entire thread thoroughly again and will stick to that thread instead.

Thanks!
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neavissa

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2376 on: February 18, 2015, 11:02:27 PM »
Hi,

Maybe someone can take the time to clarify something for me?! I thought I had it all figured out, but for some reason, I am totally lost now.  :-[ :-[ :-[

I thought that in order to get those nice HDR picture as posted in post #1, all you have to do is, shoot them in your camera, take the RAW file, drag it onto cr2hdr.exe and the end result will be a killer looking HDR .dng file??? I guess I am wrong, right?! The way it looks to me is, that I am THEN supposed to take the .dng file and import it to a Photo editing software like Lightroom or Photoshop and THEN create the final HDR image?! Is that correct?!

The other thing I am not getting is, what is the cr2hdr Lightroom plugin for?!

SO all in all, I am not sure what software does what and if any other steps have to be taken, in order to get those nice HDR images?!

thanks,

G

p.s. YES, I read this thread, not all of it, googled and tried what not, but I cannot figure it out! I am lost!
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garry23

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2377 on: February 19, 2015, 12:26:54 AM »
Neavissa

You might wish to reread what Dual ISO is all about.

Put simply, dual ISO achieves a two image bracket but in a single frame.

The two images are captured at the same time and interlaced in the image, hence the cr2hdr process is taking the interlaced data and creating a new digital negative, ie a DNG.

The interlaced images are separated in exposure space by different ISOs, ie the two ISO, interlaced  brackets, have the same aperture and shutter speed.

The DNG negative will definately need post processing, as any RAW image will.

The advantage is that the dual ISO will have 2-3 stops of additional dynamic range.

For optimum capture use ETTR and dual together, ie push the tonal data to the right, without overexposing, and 'fill in' the shadows with dual ISO.

neavissa

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2378 on: February 19, 2015, 07:42:54 AM »
Neavissa

You might wish to reread what Dual ISO is all about.

Put simply, dual ISO achieves a two image bracket but in a single frame.

The two images are captured at the same time and interlaced in the image, hence the cr2hdr process is taking the interlaced data and creating a new digital negative, ie a DNG.

The interlaced images are separated in exposure space by different ISOs, ie the two ISO, interlaced  brackets, have the same aperture and shutter speed.

The DNG negative will definately need post processing, as any RAW image will.

The advantage is that the dual ISO will have 2-3 stops of additional dynamic range.

Thanks for the reply. I got all of this so far, but I am still not sure what the difference is between using cr2hdr.exe, or the Lightroom plugin?! It seems like both "methods" achieve the same thing, right?!

Quote
For optimum capture use ETTR and dual together, ie push the tonal data to the right, without overexposing, and 'fill in' the shadows with dual ISO.

I am going to have to look up how to use ETTR and dual together...

thanks,

G
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walter_schulz

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2379 on: February 19, 2015, 07:50:33 AM »
Dual-ISO LR plug-in is in fact using cr2hdr/cr2hdr20.
It's kind of a wrapper with a GUI + integration in LR.

garry23

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2380 on: February 19, 2015, 02:16:18 PM »
Neavissa

Walter has clarified the .exe use.

As for ETTR there are two basic ways of integrating it with dual.

You can get ETTR to automatically call it when it thinks it is required, ie when certain criteria are met.

Personally, I prefer to make this decision myself. For instance, I use ETTR to set the base exposure, at ISO 100, and take a dual with this ETTR exposure setting.

A nice feature is that you can tell duel to only take a dual every other shot, hence take two images and one will be dual and one will be non-dual.

mothaibaphoto

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2381 on: February 19, 2015, 05:04:01 PM »
I reach the limit on the command line length while try to run cr2hdr-20bit.exe --same-levels - "The filename or extension is too long". Please, folder, or file mask option.

walter_schulz

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2382 on: February 19, 2015, 05:09:48 PM »
Open commandline
subst X: C:\my_very_long_and_therefore_limited_path_length_which_will_cause_trouble_with_this_application_but_there_is_a_workaround

mothaibaphoto

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2383 on: February 19, 2015, 05:25:04 PM »
I have dual ISO video with several thousand frames in each MLV file. I want to process every shot with same black levels, or whatever else --same-levels do. I can't shorten pathnames anymore.

Walter Schulz

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2384 on: February 19, 2015, 05:55:42 PM »
[ ] You have tested what I wrote.
You can assign any directory (=path name) to any drive letter not yet occupied.
Photogs and videographers: Assist in proof reading upcoming in-camera help!. Your input is wanted and needed!

mothaibaphoto

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2385 on: February 19, 2015, 06:25:52 PM »
You misunderstand the problem. MLV dump produce files with ten symbols at least. Like this one - 000000.dng. I need to pass several thousands filenames in one command line. Doesn't matter, how short the pathname to folder with all these files - the command line gets too long due to files quantity, not the redundantly long folder name i put them in.
When i deal with ffmpeg, or, let say adobe DNG converter, I can pass folder and/or file mask as parameter. I ask the same thing for HDR tool. There is NO easy workarounds.

dmilligan

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2386 on: February 19, 2015, 08:09:45 PM »
you can accomplish this with xargs and pipes on *nix operating systems:
Code: [Select]
find /path/to/dir/with/images -name '*.dng' | xargs cr2hdr --same-levels

you can apply the same whitelevel to all DNGs with exiftool in the same way (this is all that --same-levels does)
Code: [Select]
find /path/to/dir/with/images -name '*.dng' | xargs exiftool "-WhiteLevel+=50000" -overwrite_original

there's probably a similar way to do this on windows, but I'm no windows shell expert

a1ex

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2387 on: February 19, 2015, 08:56:35 PM »
Wrong answer, because --same-levels only works if all the filenames are passed in a single command line. But xargs will pass each .dng to a separate instance of cr2hdr, which effectively cancels the effect of --same-levels.

And on *nix, command line length is less likely to be an issue anyway. On my system is 2 MB, and on Mac it seems to be around 256K.

For Windows, one has to implement a FindFirst/FindNext loop to handle wildcards. On *nix, these are expanded by the shell.

For the exiftool method, no workarounds should be required. Note the command is a little different:
http://www.magiclantern.fm/forum/index.php?topic=7139.msg114254

Danne

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2388 on: February 19, 2015, 09:00:42 PM »
Find args is the best. What got me starting my unix playing thanks to dmilligan.

About same levels.

If you run command below it will take the whitelevel from your first file and apply to all the rest of your files. If you  delete the line -overwrite original it will keep a copy of your file. I had some problems on external drive with exiftool.

exiftool -tagsfromfile *.DNG -exif:whitelevel -overwrite_original

Simply write cd drag your folder here exiftool -tagsfromfile *.DNG -exif:whitelevel -overwrite_original hit enter.


This mac app workflow will also correct same levels when run in folders with dng files.
http://www.magiclantern.fm/forum/index.php?topic=13512.0


*update. Sorry, didn,t notice you were looking for a windows solution.




mothaibaphoto

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2389 on: February 20, 2015, 05:38:49 AM »
Thank you all.
Apologies I didn't find this was explained in details before.
@Danne: Use the /D switch to change current drive in addition to changing current
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ganselm

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2390 on: February 23, 2015, 05:23:13 PM »
I'm using Dual ISO on my EOS M quite successfully for a while and  *really* like it. However, during some shots over the weekend I encountered a banding artifact after using cr2hdr.exe and cr2hdr20bit.exe (used several different versions, the result always was the same)

Here's a crop of the image:

https://www.dropbox.com/s/6rfiwz5gcawgcua/banding.jpg

and here's the according debug black frame I saved.

https://www.dropbox.com/s/7edcyuc0yawq0wc/black.jpg

There's a --no-stripe-fix option which sounds like maybe this is already known? But unfortunately it seems as if it doesn't work.

Could someone give me a hint where to find the source code of cr2hdr?? Is this one the newest one? (bitbucket is not working right now, so I cannot open the link):

https://bitbucket.org/hudson/magic-lantern/branch/cr2hdr-20bit

I've some background in that field and would like to contribute if I'm able to get the stuff compiled.

Any suggestions? I actually traveled to the Anza Borrego desert staying in the desert during the night listening to coyotes and rattlesnakes to capture some night shots and would really like to rescue those pictures....

a1ex

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2391 on: February 23, 2015, 05:35:23 PM »
Can you upload the CR2?

ganselm

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2392 on: February 23, 2015, 07:03:01 PM »
Thanks for the quick reply a1ex. This one:

https://www.dropbox.com/s/yqpstzr1k30kxoh/_MG_2113.CR2?dl=0

is a similar shot with the same behavior after converting to DNG

Randallsart

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2393 on: February 27, 2015, 04:59:27 AM »
New to ML. I have a question. After I export from LR, then what?

Audionut

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2394 on: February 27, 2015, 01:30:36 PM »
Post process.

Randallsart

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2395 on: February 27, 2015, 07:41:01 PM »
okay I figured it out. I could not find the dng file. I was thinking it would automatically re import into LR.

a1ex

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2396 on: February 27, 2015, 09:35:52 PM »
[...] I encountered a banding artifact after using cr2hdr.exe and cr2hdr20bit.exe [...]

As you have guessed, the issue appears during the black level correction step (black_subtract, most likely the first half). It has nothing to do with --no-stripe-fix.

The OB areas appear correct though, so I'm not yet sure what causes it.

Edit: found the problem - a hot pixel in the top optical black area! Solution: use median instead of averaging.

The source code link from your post is correct.

ganselm

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2397 on: February 28, 2015, 04:23:00 AM »
Wow a1ex, thanks for your quick fixing.

I'm currently travelling and will try to build the stuff when I'm back. Would you be able to build a Windows executable for me beforehand or do you know someone who has the stuff ready for compilation on a windows machine?

Thanks again!

a1ex

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2398 on: February 28, 2015, 09:56:19 AM »
I didn't fix it yet, only found the problem and suggested a fix.

ganselm

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Re: Dual ISO - massive dynamic range improvement (dual_iso.mo)
« Reply #2399 on: March 01, 2015, 03:38:49 AM »
a1ex committed d397c38 5 hours ago

but now you did =)