Author Topic: dual_iso with linux  (Read 2776 times)

rkonrad

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dual_iso with linux
« on: October 09, 2014, 07:15:09 PM »
Sorry if this post is already present - I'm not able to find a similar posting:

I accidentally left the dual_iso function set for most of my shots which was for a very important anniversary celebration.  With the help of wine, I was able to process them to DNGs using cr2hdr.exe.  The pictures look fine and no different than any of the other pictures I took without this setting.  Some have a high dynamic range and others do not but I was hoping to take advantage of this accident and show improved pictures for those with the high dynamic range.  So I took the shots with the same exposure setting as I would normally use (without the dual_iso setting).  I was wondering if I have done exactly what I'm supposed to do with "wine cr2hdr.exe [files]" or is there an extra step I'm supposed to take?  The processing got rid of the lines which I"m assuming are the dual iso settings but there are still over-exposed and under-exposed portions of the image.

Also, is there a linux alternative I should be using?

I'm post-processing using Darktable.

Cheers

Richard

ayshih

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Re: dual_iso with linux
« Reply #1 on: October 10, 2014, 09:39:27 PM »
Yes, the converted dual-ISO shots will look qualitatively the same as normal shots taken at the same exposure settings (at the lower ISO).  However, the difference is there when you manipulate the photo in post (e.g., Darktable).  For example, if you increase the exposure, you should see noticeably less noise in the shadows.  This gives you more post-processing latitude, including if you want to apply crazy "HDR" effects.

For Linux, you can build a native version of cr2hdr from the source code, but if running it through Wine works for you, there should be no difference in the output.  Note that you should probably use the 20-bit version (cr2hdr-20bit.exe), which has a bunch of improvements.
Canon EOS 50D | 17–40mm f/4L & 70–300mm f/4.5–5.6 DO IS | Lexar 1066x

rkonrad

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Re: dual_iso with linux
« Reply #2 on: October 12, 2014, 09:15:22 PM »
Thanks.  Yes I noticed that when I increase exposure there is minimal noise.  Also I didn't ETTR so I"m sure I'm not getting full benefit.  Yes Wine works perfectly well and I'll just stick with it.

Cheers
Richard