DUAL ISO cr2hdr. Why output a DNG and not a CR2?

Started by jml2017, December 10, 2017, 11:26:59 PM

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jml2017

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

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

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

Somebody actually looked into it and managed to write a CR2.

Don't remember the source code being published anywhere.

jml2017

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

Automatic correction of lateral/transverse CAs is very basic to most RAW converters/image processing tools. Take your choice.

jml2017

EOS 6D