Digikam raw files and darktable

[Andrey Goreev]

Hello Juan,
Whatever you do with a RAW file in darktable is being stored in a sidecar file (xmp). So the xmp's are not only about tags, camera model, etc. If digikam was able to read darktable's xmp it would show the image properly (according to the changes you made in darktable) and I guess the thumbnail would look correct (I am not sure about that, this might be the hardest part).I am not sure I will be able to do the whole project but I can try anyways. Who knows, maybe I am good at it :).
-------- Original message --------From: Juan Jose Casafranca <jjcasmar at gmail.com> Date: 2017-01-06  7:04 PM  (GMT-07:00) To: digiKam - Home Manage your photographs as a professional with the power of open source <digikam-users at kde.org> Subject: Re: Digikam raw files and darktable 
Hi Andrey,

I understand the problems that you are telling. 
I understand that some software doesn't respect the xmp tags created by other.
That would be easily solved only supporting processors that respect other 
software tags (I feel that respecting what other programs write is important 
for compatibility)
I don't think reading is a problem, if a software doesn't understand a tag, 
simply ignore it. 

I dont think digikam need to read darktable tags. My idea is to create a 
plugin in which you specify which raw processor you want to use. When a raw 
file is found, simply call the raw processor with the xmp sidecar and get the 
image that the processor generates. 

Darktable doesn't need to read digikam tags, does it? What happens when 
darktable founds a tag which doesnt know how to interpret?

About the standards, of course. I think that the xmp files should have a set of 
standard tags (for example, title, lens, camera, keywords...) and other 
software specific. Doesn't xmp files already work this way? When a new editing 
is done with digikam, you can simply generate a new xmp, the same way that you 
will generate two of them in darktable if you duplicate the picture. 

I think that doing some kind of xmp standard file and letting different 
software communicate through it is the correct way to do things. 

About the pp3 files from raw therapee. Why not? My idea is to do this asking 
the user which processor is going to use for raw editing. If the users says 
that raw therapee, digikam simply calls raw therapee (feeding it with the pp3 
file). The only condition is the software to be used as a library. Anyway, I 
wont implement that, I'm focused on the darktable because is the software I 
use. If someone wants the raw therapee... he can do it :-)

I think that if we design a good plan to implement all this, developers from 
different software will be please to be part of it. 

Would you like to help me with this?

On viernes, 6 de enero de 2017 15:09:37 (CET) Andrey Goreev wrote:
> darktable never saves any changes to RAW files. All changes are to be saved
> in sidecar file originalfilename.xmp
> Both digikam and darktable will be reading and writing the same sidecar
> file.
> There are few issues here:
> - Writing - Some programs do not respect changes made by another programs
> and overwrite them;
> - Read - Some programs do not recognize code added to an xmp-file by
> another programs.
> Please see an example of an XMP file created by darktable attached. You
> will see that digikam's xmp will be different.
> 
> So what needs to be done here?
> Someone needs to work with both digikam and darktable devs and make sure
> that:
> 
> - digikam can read changes added by darktable (processing filters, etc.)
> - darktable can read changes added by digikam (tags, etc.)
> - digikam and darktable use same xmp standards and do not duplicate any
> information; (e.g. darktable can add keywords (tags); digikam can do RAW
> editing)
> - digikam and darktable respect each others code added to xmp and do not
> overwrite anything
> 
> Sounds like a lot of work but I do not think there will be much actual
> coding required from the person. It will be mostly communication and it
> will be tough since the devs might have different vision on the subject.
> 
> 
> I personally think it is a great idea. Actually I have seen similar wishes
> on discuss.pixls.us. I think that champions from pixls.us (well respected
> open source photographers) could become that compound that glues up the two
> pieces of software together.
> 
> 
> PS But be ready to hear "But how about RawTherapee and its pp3 files?"
> 
> Best regards,
> Andrey Goreev
> 
> On Fri, Jan 6, 2017 at 1:53 PM, Eduard Zalar <eduard at zalar.de> wrote:
> > OK, thanks.
> > 
> > That's the information I didn't know because I do not work with raw
> > files.  Hopefully you can find a good solution.
> > 
> > 
> > Juan Jose Casafranca <jjcasmar at gmail.com> schrieb am Fr., 6. Jan. 2017 um
> > 
> > 21:49 Uhr:
> >> I have also thought something like that. The problem is that raw
> >> processors usually dont touch the original raw file. The only output an
> >> xmp
> >> file. With this in mind, is common to duplicate the xmp file to different
> >> processes, so you end with only a raw file but several xmp files for that
> >> raw file (imagine you want a black and white version of a photo but also
> >> the color version). Therefore, it's not possible to just update the
> >> embedded file, because there is not just one unique output from the raw
> >> processor :-)
> >> 
> >> 2017-01-06 21:46 GMT+01:00 Eduard Zalar <eduard at zalar.de>:
> >> 
> >> Hi,
> >> 
> >> this is an interesting discussion.
> >> 
> >> Wouldn't it be better to enable darktable to update the embedded JPEG
> >> image in the raw file?
> >> 
> >> In this case digiKam would detect a change in the file and automatically
> >> update the thumbnail, isn't it?
> >> 
> >> It's just an idea...
> >> 
> >> Normally, I do not use raw files so I don't know if there may exist
> >> another restriction which avoids this.
> >> 
> >> Regards
> >> Eddie
> >> 
> >> 
> >> 
> >> Simon Frei <freisim93 at gmail.com> schrieb am Fr., 6. Jan. 2017, 20:47:
> >> 
> >> First thing to do is open a bugzilla issue where you describe what you
> >> want:
> >> https://bugs.kde.org/enter_bug.cgi?product=digikam&format=guided
> >> There you probably get better pointers for where to start from
> >> experienced devs, I never worked with that part of the code. This is the
> >> function that creates thumbnails:
> >> https://cgit.kde.org/digikam.git/tree/libs/threadimageio/
> >> thumbnailcreator.cpp?id=429fa5fd8e7f53b74c82eb19dffb2e6cf4b4325c#n455
> >> 
> >> 
> >> On 06/01/17 20:18, Juan Jose Casafranca wrote:
> >> 
> >> Yes, exactly, that is my suggestion :-)
> >> I think that it will give digikam a great boost if it can communicate
> >> with specific raw processors :-)
> >> 
> >> I understand that it could be an intensive task, but there are some ways
> >> to limit the heavyness.
> >> For example, digikam should only process the new thumbnail when darktable
> >> is opened through digikam interface and at the beginning.
> >> Or maybe just marking which files are dirty and then calling darktable in
> >> lib mode to update those thumbnails.
> >> 
> >> I would be happy to work on something like this. Any idea on where to
> >> begin with? Ive never touched the digikam code ^^
> >> 
> >> Cheers
> >> 
> >> 2017-01-06 20:10 GMT+01:00 Simon Frei <freisim93 at gmail.com>:
> >> 
> >> Hi,
> >> 
> >> Do I understand you correctly: You want thumbnails of raw files that are
> >> adjusted based on the processing profiles of darktable?
> >> If that is the case, it is (currently) not possible in digikam. And such
> >> a function would certainly be very resource heavy, as for every
> >> thumbnail on every change darktable had to process the raw file.
> >> The interface between digikam and other photo editing software could
> >> certainly be improved (e.g. versioning too), so I would be very happy if
> >> you would work on that in any way;)
> >> 
> >> Cheers,
> >> Simon
> >> 
> >> On 06/01/17 20:01, Juan Jose Casafranca wrote:
> >> > Hi everybody,
> >> > 
> >> > I would like to know if there is any easy way to use digikam as a photo
> >> > management software and use darktable for raw editing.
> >> > 
> >> > The main issue I'm finding when I try to do this is this one
> >> > -Raw thumbnails are loaded from the jpeg embeded file and when I change
> >> 
> >> process
> >> 
> >> > my photo in darktable, this thumbnail isn't changed in digikam
> >> > 
> >> > It would be nice that digikam reads the darktable sidecar and uses an
> >> 
> >> specified
> >> 
> >> > software (or digikam editor tool if no software is specified) to load
> >> 
> >> the
> >> 
> >> > preview file for raw pictures. Is there any way to do this?
> >> > 
> >> > If there's no such way to do this, I will be happy to post it in the
> >> > developers mailing list and try to implement it, because I feel that
> >> 
> >> darktable
> >> 
> >> > management features are far away from digikam ones and digikam editor
> >> 
> >> features
> >> 
> >> > are far away from darktable ones. It would be nice to have both
> >> 
> >> softwares
> >> 
> >> > working together :-)
> >> > 
> >> > Any idea?


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