Author Topic: DUAL ISO cr2hdr. Why output a DNG and not a CR2?  (Read 469 times)

jml2017

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DUAL ISO cr2hdr. Why output a DNG and not a CR2?
« on: December 10, 2017, 11:26:59 PM »
Hello Magic Lantern gurus,

I have just installed Magic Lantern as I am curious about the DUAL ISO module.
I have a question. The answer may be obvious for people familiar with the differences between DNG and CR2 formats, but I am wondering:
Is there a fundamental reason why the output of cr2hdr is a DNG file and not a CR2 file? Or could it be done (provided there is time and interest in it)?

Please enlighten me!

Thanks.

EOS 6D

Walter Schulz

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Re: DUAL ISO cr2hdr. Why output a DNG and not a CR2?
« Reply #1 on: December 11, 2017, 09:39:29 PM »
CR2 -> Proprietary format. Specs not open to public.
DNG -> Open format.

Why on earth should a project dedicating itself to open source philosophy even consider using CR2? Do you *need* CR2 for your workflow or any other reason?

jml2017

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Re: DUAL ISO cr2hdr. Why output a DNG and not a CR2?
« Reply #2 on: December 11, 2017, 10:02:21 PM »
Up to now I only use Canon DPP for my workflow. It deals well with Lens Aberrations and gives me enough sliders to gently adjust the image.
I do not say I absolutely need cr2. I am happy to deal with Dual ISO images in another software specifically.
Am I wrong or isn't some part of the cr2 format understood enough to be able to write a cr2 file out of cr2hdr? Or does this just make no sense (independently from the fact that cr2 is proprietary format or not)?
EOS 6D

a1ex

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Re: DUAL ISO cr2hdr. Why output a DNG and not a CR2?
« Reply #3 on: December 11, 2017, 11:07:47 PM »
Somebody actually looked into it and managed to write a CR2.

Don't remember the source code being published anywhere.

jml2017

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Re: DUAL ISO cr2hdr. Why output a DNG and not a CR2?
« Reply #4 on: December 18, 2017, 11:00:08 PM »
Thanks for the information.
I am trying to figure out how to apply Chromatic aberration corrections outside DPP since we use DNG on the hdr image. Ideally I am looking for a solution similar to Digital Lens Optimizer from DPP. Unfortunately, I am not sure that it really possible since I believe there is no focus information in DNG, Correct?
EOS 6D

Walter Schulz

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Re: DUAL ISO cr2hdr. Why output a DNG and not a CR2?
« Reply #5 on: December 18, 2017, 11:16:31 PM »
Automatic correction of lateral/transverse CAs is very basic to most RAW converters/image processing tools. Take your choice.

jml2017

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Re: DUAL ISO cr2hdr. Why output a DNG and not a CR2?
« Reply #6 on: December 21, 2017, 10:29:44 PM »
OK. I am trying Rawtherapee.
EOS 6D