> I recently purchased a Canon EOS 80D, I am a Debian (8.7) user. All this
> is quite new to me so it might be a newbie question rather than a
> problem with Darktable. Sorry beforehand if that is the case.
>
> TL;DR: http://imgur.com/a/eEipd
>
> When importing photos (CR2) into Darktable (2.0.7),
> colors/contrast/brightness... aren't the same as in the "Gnome Document
> Viewer" preview (and on the screen of my 80D).
What I suspect is happening here is that the version of the image that
the Gnome Document Viewer preview and the 80D are showing you comes from
a 'preview' JPEG that is embedded into the RAW file (most RAW files have
several preview JPEGs in them at various sizes). This preview JPEG has
had all of the camera-specific magic processing applied to it, including
any in-camera styles you either set yourself or that Canon applies by
default.
The darktable picture seems to be from the darkroom, where darktable
is processing the RAW itself from scratch. This from-scratch processing
almost never exactly duplicates the camera's own processing (partly
because camera makers never tell anyone what the in-camera stuff is
actually doing), and is sometimes not at all similar to it depending on
what settings the camera and darktable have. Generally the further from
'basic neutral' you have the camera on, the more divergence there is
going to be.
(Note that most cameras don't come set to 'basic neutral' out of the
box; usually their default picture setting is more cranked up than that,
because it looks nicer on the back of the screen and when people just use
the JPEG defaults.)
This is an issue in any RAW processor (apart from the ones from the
camera companies themselves), because none of them know exactly what
the in-camera processing is doing. Some RAW processors devote more
engineering and development effort to closely matching the straight
out-of-camera processing than others do, and so will come closer to the
look of those JPEGs by default. My impression is that darktable chooses
to focus development efforts elsewhere, so it winds up not necessarily
very close for many cameras and many camera styles.
(There are ways to get it closer in some areas if you want to do
some hand work. There are darktable tools that take some RAWs and
some corresponding JPEGs and work out much of the intensity/contrast
mapping between them to create a custom 'base curve' for the camera and
style. However cameras also often add things like colour shifts and
various sorts of sharpening and so on, and those are generally not going
to be duplicated through the base curve's mapping of intensities.)
- cks
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