R&Darktable: exporting from DNGs results in very dark JPEGs and PNGs; OK from CR3s

Not sure whether this is the right place to address this problem; if not please advise.

When I got my Canon R5 in June of last year, .CR3 Files could not easily be processed in Darktable 3.6. Adobe’s old DNG-Converter produced DNGs that Darktable did read, but they looked horrible. However, DxO’s Pure Raw resulted in very nice looking DNGs. Since version 3.8, Darktable was then easily able to process .CR3 files, but usually the DxO results are cleaner (no wonder, for the price), although sometimes a bit oversharpened.

I’m currently using Aurelien Pierre’s R&Darktable and ran into the following problem:

Having two versions of the same file, .CR3 and .DNG, processed to look roughly similar, I tried to export both to a JPEG. But while the JPEG originating from the .CR3 file looks fine, the one from the DNG is way too dark. The same problem occurs when exporting PNGs.

You should report rdarktable issues here: Issues · Aurelien-Pierre/R-Darktable · GitHub

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Have you tried plain darktable 4.0? You may find it has more people using and supporting/developing it.

DxO is likely doing a lit more processing by default than either darktable or rdarktable.

DxO has a ‘leave stuff alone’ mode for exporting DNG’s. It’s then the pure data with only demosaicing done. Even it’s highlight-recovery is then turned off.

If you turn off all the modules in DxO and export a ‘full edits DNG’, it’s still basically like-for-like with the RAW file, only the highlight-reconstruction is engaged (and of course demosaicing since it’s a linear DNG). I use DxO as a ‘preprocessor’ a lot of the time, and both with r-darktable and darktable master since 3.4+.

I never had issues with the export. I can only imagine that one of the exports had a different output profile selected (or maybe something is set to ‘same as input’ and that screws things up with DNGs I’m guessing. I’ve read Aurélien talking about this while trying to work on issues with the output profile conversion.

So, double-check the export is set to the same output profile in both cases (likely regular ‘sRGB’ is fine, if nothing more but to test my theory).