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How to remove "left behind" tag tree

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tosca

Re: How to remove "left behind" tag tree

It would be even better if such a GUI could be incorporated in Digikam batch tool. I don't relish having to use several different programs along my "ordinary" workflow; Digikam + Darktable are enough for me. If only one of them could do the job of both...

Marie-Noëlle

2012/11/12 David Vincent-Jones <[hidden email]>

It looks to me as if Linux could really do with a version of Exiftool GUI; that would allow easier bulk metadata manipulation. Possibly it would run under Wine.

David

Mes dernières photos sont dans ma galerie.
Retrouvez-moi aussi sur mon blog.
Et parcourez les Cévennes à ma façon avec Cévennes Plurielles,

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Elle Stone

Re: How to remove "left behind" tag tree

I posted an article with example exiftool commands for wholesale
removal of digiKam-written metadata:
http://ninedegreesbelow.com/photography/dam-software-metadata.html

For every bit of metadata that you add with digiKam, usually more than
one metadata field get written to the image. For instance tag tree
information needs to be removed from three metadata locations, rating
information from 4 locations, caption information from 7 locations,
and so on.

Exiftool is very powerful and works fast. Which means a mistyped
command can wreck havoc on your image files. So please, please, please
make a backup of your images and your digiKam database, and make sure
that Exiftool is doing exactly what you want, by trying all the
commands on a test folder of images, before deploying on images that
matter.

I went through the procedure outlined in the article with all of my
own images, and once I worked out which commands to use, the procedure
was relatively painless and quick. I ended up finding and removing a
ton of old, unwanted, and out-of-date metadata left behind by various
DAM softwares that I've used at one time or another (digiKam isn't the
only DAM software that can leave metadata in a messy state).

Once all tag-tree information is removed from the image files, if
digiKam is at least temporarily set up to not write to the image files
(only to the database), then you can rearrange the tag tree without
creating left-behind, unwanted tags. Unfortunately, as soon as you
start writing tags to the image again, then rearranging the tag tree
will result in image and database again being out of synchronization.

Elle

--
http://ninedegreesbelow.com
Articles and tutorials on open source digital imaging and photography
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tosca

Re: How to remove "left behind" tag tree

Thanks a lot for these information.
I'll save this for a moment when I'll have more time to do everything at my own pace; to much to do at the moment, it would result in mistakes if I try to do such thing in a hurry!

And one might hope ... in the mean time, the future 3.0.0 Digikam release might bring some good news on the subject.

Marie-Noëlle

2012/11/12 Elle Stone <[hidden email]>

I posted an article with example exiftool commands for wholesale
removal of digiKam-written metadata:
http://ninedegreesbelow.com/photography/dam-software-metadata.html

For every bit of metadata that you add with digiKam, usually more than
one metadata field get written to the image. For instance tag tree
information needs to be removed from three metadata locations, rating
information from 4 locations, caption information from 7 locations,
and so on.

Exiftool is very powerful and works fast. Which means a mistyped
command can wreck havoc on your image files. So please, please, please
make a backup of your images and your digiKam database, and make sure
that Exiftool is doing exactly what you want, by trying all the
commands on a test folder of images, before deploying on images that
matter.

I went through the procedure outlined in the article with all of my
own images, and once I worked out which commands to use, the procedure
was relatively painless and quick. I ended up finding and removing a
ton of old, unwanted, and out-of-date metadata left behind by various
DAM softwares that I've used at one time or another (digiKam isn't the
only DAM software that can leave metadata in a messy state).

Once all tag-tree information is removed from the image files, if
digiKam is at least temporarily set up to not write to the image files
(only to the database), then you can rearrange the tag tree without
creating left-behind, unwanted tags. Unfortunately, as soon as you
start writing tags to the image again, then rearranging the tag tree
will result in image and database again being out of synchronization.

Elle

--
http://ninedegreesbelow.com
Articles and tutorials on open source digital imaging and photography

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Elle Stone

Re: How to remove "left behind" tag tree

On 11/14/12, Marie-Noëlle Augendre <[hidden email]> wrote:
> Thanks a lot for these information.

You are welcome! As this was the second time I needed to figure out
the exiftool commands to clean out metadata (digikam is not the only
DAM that can create a lot of messy metadata), I decided to post a "how
to" on my website.

You mentioned maintaining two digiKam databases by setting up a second
user. There is another way, which is to make two installations of
digiKam, one in the usual place, another in your home folder perhaps.
The second installation has to be set up to use its own separate .kde4
settings folder or else they'll both try to write to the same
database.

I've done that once before, one install for production version of
digiKam, one for testing version. But I don't see why you couldn't do
two installations of the same version of digiKam. Unfortunately I
don't remember how it's done, and it does require installing the
second digiKam from source.

Does anyone on the list have a link to how to create two digiKam
installs each with its own settings folder? I think there used to be
instructions somewhere on the digiKam website.

Cheers,
Elle
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Jean-François Rabasse

Re: How to remove "left behind" tag tree

In reply to this post by Elle Stone

Hello,
a late comment about this issue :

On Mon, 12 Nov 2012, Elle Stone wrote:

> Once all tag-tree information is removed from the image files, if
> digiKam is at least temporarily set up to not write to the image files
> (only to the database), then you can rearrange the tag tree without
> creating left-behind, unwanted tags. Unfortunately, as soon as you
> start writing tags to the image again, then rearranging the tag tree
> will result in image and database again being out of synchronization.

Yes, I had noticed that too.
It appears to me that it's an inconsistency problem inside Digikam.
When writing to image, the database metainformation is written
in « replace mode », i.e. all existing information in the image
is fully replaced by database info. As for tags, if the image had
existing « old » tags, they are removed and replaced with the
current tags list in the DB.

When reading from an image, atomic information (rating, title et al.)
replaces the current database information for that image.
But tagslist are read in « append » mode and added to current tags.
So, if you reorganize tags in Digikam, previous old tags in the image
will be added to current tags, and the mess starts.

Briefly said, the read and write metadata functions are not reversible.
Write synchronizes, DB to image, read doesn't.
And the only solution is what Elle said, write current data to images,
destroy all tags, or even destroy the DB, then restart on a new basis
with metadata rebuilt from images.

IMHO I think this should be either fixed or documented to help users
reorganize their tags.
The « Write Metadata to All Images », in the Tools menu, may help to
resynchronize images from DB. (If writing the tags is checked in the
metadata settings folder.)
And keep in mind that synchronizing DB from images is impossible with
the current implementation.

Hope this could help making things a bit more clear.

Regards,
Jean-François
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tosca

Re: How to remove "left behind" tag tree

Thanks for your comment, Jean-François.

I think it NEEDS to be fixed.
Otherwise, even if one cleans the mess one day and begin again from scratch, he's stuck to keep the same tags structure forever; or, he will move/add something and begin another mess!

Who is completely sure the tags structure he (intends to) uses just now will be the same he wants in some future. Not me, for sure...

Marie-Noëlle

2012/11/20 Jean-François Rabasse <[hidden email]>

Briefly said, the read and write metadata functions are not reversible.
Write synchronizes, DB to image, read doesn't.
And the only solution is what Elle said, write current data to images,
destroy all tags, or even destroy the DB, then restart on a new basis
with metadata rebuilt from images.

IMHO I think this should be either fixed or documented to help users
reorganize their tags.
The « Write Metadata to All Images », in the Tools menu, may help to
resynchronize images from DB. (If writing the tags is checked in the
metadata settings folder.)
And keep in mind that synchronizing DB from images is impossible with
the current implementation.

Hope this could help making things a bit more clear.

Regards,
Jean-François
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Jean-François Rabasse

Re: How to remove "left behind" tag tree

On Tue, 20 Nov 2012, Marie-Noëlle Augendre wrote:

> Thanks for your comment, Jean-François.
>
> I think it NEEDS to be fixed.
> Otherwise, even if one cleans the mess one day and begin again from scratch,
> he's stuck to keep the same tags structure forever; or, he will move/add
> something and begin another mess!
>
> Who is completely sure the tags structure he (intends to) uses just now will
> be the same he wants in some future. Not me, for sure...

Not me neither :-)

And it's not only a matter of tags structure but also of tags language.
The same tags, or indexes, may have different representations in different
languages, even if they refer to exactly the same things.
As an example, if one wants to keep the location where images have been
shot, e.g. country and city, this is definitive information. But the
tags list may differ.
In French :
paris -> Lieu/France/Paris
vienne -> Lieu/Autriche/Vienne

And if I tag for English users, the same locations become :
paris -> Location/France/Paris
vienne -> Location/Austria/Vienna
or in German :
paris -> Ort/Frankreich/Paris
vienne -> Ort/Österreich/Wien
etc.

It's a very complicated problem and my personal option is to use
a vocabulary of keys. Can be a controlled vocabulary or just a
managed vocabulary, but something unambiguous.
Keeping track of the keys (somewhere in XMP data) and the tags
translation from a vocabulary file allows to modify the definitions
of keys, reorganisation, language switching, and rebuild the tags
structure.

Tags tree are only useful to make organisation more readable and
logical, but in fine, the important thing is the terminal keywords,
all what is used to define a « subject ».
Applications that use keywords, use a subject flat list of words,
never hierarchy. E.g. a web albums builder may insert in generated
XHTML code some definitions as :
<meta name="keywords" content="xxxx, zzzz, ..." />
(That's one of the reasons why I prefer to have metadata in files,
to allow other applications to use the work done.)

In the above example, from the same keys, paris or vienne, the final
subject could be Paris or Vienne, or Paris or Vienna, or Paris or Wien,
depending on a vocabulary translation table. But the keys are eternal.
The important thing, IMHO, is to keep aware of the difference between
a tag semantic and a tag structured representation.

But this is off topic anyway :-)

Regards,
Jean-François
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tosca

Re: How to remove "left behind" tag tree

Well, that's even a step further.
If only it could work properly in one language yet...

I understand it won't be enough for photographers intending to use tags as a way of making their work better known (my guess is they will use the englis version in this case); but for those of us (the great majority?) who use tags mainly to organise their pictures locally, even one language working well will be a huge improvement.

Marie-Noëlle

2012/11/21 Jean-François Rabasse <[hidden email]>

On Tue, 20 Nov 2012, Marie-Noëlle Augendre wrote:

Thanks for your comment, Jean-François.

I think it NEEDS to be fixed.
Otherwise, even if one cleans the mess one day and begin again from scratch,
he's stuck to keep the same tags structure forever; or, he will move/add
something and begin another mess!

Who is completely sure the tags structure he (intends to) uses just now will
be the same he wants in some future. Not me, for sure...

Not me neither :-)

And it's not only a matter of tags structure but also of tags language.
The same tags, or indexes, may have different representations in different
languages, even if they refer to exactly the same things.

Jean-François Rabasse

GPS Reverse Geocoding

In reply to this post by tosca

Hello,

I wonder what the Reverse Geocoding function, in Digikam Geolocation
dialog, is expected to do ?

I did several tries, selecting images with GPS information, opened
the Reverse Geocoding folder, choose one of my base tag, Location,
then clicked on Apply reverse geocoding, then Apply.
Seemed to do nothing, at least nothing I could see.
I've even tried again, checking the box Write tags to XMP, and
generated a xmp sidecar file with no location information. :-(

Do some users use this function, how, and to do and expect what ?

Thanks,
Jean-François

PS: what I'd like to do is automatic insertion of location tags with
country and city. Technically it's possible, I wrote a small shell
script around that, working the very basic way :
- extract GPS position, latitude and longitude from the image (I used
exiftool)
- connect to a reverse locating service (I used wget to geonames.org)
- process returned information to extract country and city and add a
tag, Location/<country>/<city>, in the image file (I used exiftool to
write to Xmp.digiKam.TagsList.

All I can sayt is that it works, but it's very slow and somewhat
artisanal. I'm looking for a more regular way. Any suggestions ?
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