writing tags to the files

[Johan van Noooten]

Hello All,

I'm using digiKam 2.6.0 on openSuse 12.2. I'm trying to write my digiKam "tags" as tags in the files themselves so that I can access them across my computers and operating systems. I think I'm supposed to be able to do this by using the "Album" menu and choosing "write metadata to images" or under "Image", select "write metadata to selected images". It also seems to be possible from the "captions/tags" tab on the right side, where there is a "more" button at the bottom that you can press and select it. I'm hoping then that I will be able to right click on a picture in, for example, dolphin (or windows explorer when they're viewed in Windows), access its properties and see the tags listed under "information" This does not seem to work. I don't seem to be writing them to the exif (I hope I have the name right) data on the .jpg.  It seems to be trying to write the information sometimes (I get the progress bar moving, but only with the captions/tags route), but no information is written. The tag does not appear under "information" in file properties in Dolphin. Thanks in advance.

Johan

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[Andrew Goodbody]

First of all just because other programs do not show the exif data does
not mean it is not there. Try with showFoto to see if the tags etc have
been written; my bet is that they are there. So it may just be that the
other programs you are using do not do what you want.

Secondly you can set digikam to always write the metadata to the image
files so you do not have to write it to individual files.

Andrew
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[Peter Albrecht]

Hi Johan,

did you enable
   "[x] Save image tags as 'Keywords' tags in metadata
embedded in file"

To be found under:

  "Settings" -> "Configure digikam..." -> "Metadata" ->
"Behaviour"

This should write your tags to the IPTC and XMP Metadata in
the jpg file. (As far as I know, digiKam tags are not
written to the EXIF Metadata. But I may be wrong.)

I do check this by examining the jpg files with a hex editor
like Okteta or a hex viewer like xxd (commandline tool):

 # xxd mypicture.jpg | less

You should find your tags in the right column.
E.g. after "<digiKam:TagsList>...".


The part of viewing the tags in dolphin belongs to the topic
"semantic desktop" of KDE. "Nepomuk" is another term related
with this.

Official site: http://nepomuk.kde.org/

If you are able to read German language (or willing to
accept google translation ;), have a look at this blogpost:
 >
http://beyondserenity.wordpress.com/2010/08/29/nepomuk_in_kde_-_theorie_und_praxis/

It is about nepomuk, digikam and KDE. (Back in 2010)

Personally, I have disabled Nepomuk by the time it was
introduced, a few years ago. But I should give it another
try now!

Regards,
        Peter


On 19.09.2012 02:55, Johan van Noooten wrote:

> Hello All,
>
> I'm using digiKam 2.6.0 on openSuse 12.2. I'm trying to write my digiKam
> "tags" as tags in the files themselves so that I can access them across my
> computers and operating systems. I think I'm supposed to be able to do this
> by using the "Album" menu and choosing "write metadata to images" or under
> "Image", select "write metadata to selected images". It also seems to be
> possible from the "captions/tags" tab on the right side, where there is a
> "more" button at the bottom that you can press and select it. I'm hoping
> then that I will be able to right click on a picture in, for example,
> dolphin (or windows explorer when they're viewed in Windows), access its
> properties and see the tags listed under "information" This does not seem
> to work. I don't seem to be writing them to the exif (I hope I have the
> name right) data on the .jpg.  It seems to be trying to write the
> information sometimes (I get the progress bar moving, but only with the
> captions/tags route), but no information is written. The tag does not
> appear under "information" in file properties in Dolphin. Thanks in advance.
>
> Johan

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[Jean-François Rabasse]

Hi Johan,

The « Write metadata to image » , or « to selected images » action
isn't sufficient per se.

As peter said :

On 19.09.2012 09:21, Peter Albrecht wrote:

> did you enable
>    "[x] Save image tags as 'Keywords' tags in metadata
> embedded in file"
>
> To be found under:
>
>    "Settings" -> "Configure digikam..." -> "Metadata" ->
> "Behaviour"

you have also to define explicitly which (meta)data are to be written,
it's not a « write all » feature. The Settings Metadata folder displays
several checkboxes for different data items, Title and description,
and/or Rating, and/or Tagslist, etc.

It's up to you to check/unckeck item by item, what you wish to be
written and what you prefer not to be. If you haven't check Save
image tags, DK will never write them.

Note also that in that same configuration folder, if you set the
Metadata writing mode to « Write to image only » , or « image and
sidecar file » , you won't need any more to activate the « Write
metadata to image » , it will be done each time you modify something,
the title, rating, tags, etc., without manual intervention.



About metadata being read by other applications :

It's not a simple issue because some metadata fields are more or less
standard across applications, and some other are not. To write your
image title and description, DK uses standard XMP fields, in the
Dublin Core namespace, and these could be read by other applications.

As for Dolphin, Peter answered :

> The part of viewing the tags in dolphin belongs to the topic
> "semantic desktop" of KDE. "Nepomuk" is another term related with
> this.
>
> Official site: http://nepomuk.kde.org/

NB: some images viewers, e.g. Gwenview, are more images oriented and can
display almost all metadata fields. DK tags appear with Gwenview.

However, tagslist as featured in DK have a hierarchical structure and
this is not fully supported in basic standards. So, DK saves the
information into an application dedicated namespace,
<digiKam:TagsList>, but only Digikam is supposed to be able to read
that. To increase the probability some other applications could read
the info, Digikam saves also tagslist information in several other
metadata fields, hierarchicalSubject, Keywords, Subject.
Maybe other...

This is a nice idea for increased potential interoperability, but has
two side effects :

- Some information may disappear. E.g. the standard Keywords or
Subject metadata fields format supports only a flat list of keywords,
not a hierarchical structure.
So if you have a structured tag on an image,
say /Location/France/Paris, only the tail component Paris will appear
as a keyword and another application reading metadata will no longer
be aware of the former hierarchy.

(As far as I know, only the hierarchicalSubject field ensures
compatibilty with Adobe software, without structure loss.)


- This mechanism may overwrite some standard fields if you use other
metadata edition programs. E.g. editing image title and description
will keep compatibility with DK, but image subject edition would be
destroyed the next time DK saves a tagslist.
(I'm sure of that, I've already lost subjects:-)

And this is why defining item by item what is to be written, in the
Metadata settings folder, cf. supra, is a nice feature. (This is my
personal case; I save titles and descriptions, but as I happen to edit
also subjects of my own, I don't save tagslists not to destroy my
subjects. But it's a detail.)


Regards,
Jean-François

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[Johan van Noooten]

Thanks for all the replies. I had assumed that Dolphin did the same thing as Windows Explorer in Windows 7 when I added tags to a .jpg using "properties", then "information" (Dolphin) or "details" (Windows Explorer).  But the tags I wrote using DK do appear in Windows Explorer and vice versa (perhaps not perfectly, but well enough). This is good. Those I wrote using Dolphin don't. I guess Dolphin doesn't store metadata in the .jpg file itself or it does it in a way that Windows (or DK for that matter) doesn't read. That's not a big problem for me. I use to disable nepomuk also. I don't anymore. Thanks again for the help.

Johan

 

On Wed, Sep 19, 2012 at 7:25 AM, Jean-François Rabasse <[hidden email]> wrote:

Hi Johan,

The « Write metadata to image » , or « to selected images » action
isn't sufficient per se.

As peter said :

On 19.09.2012 09:21, Peter Albrecht wrote:

did you enable
   "[x] Save image tags as 'Keywords' tags in metadata
embedded in file"

To be found under:

   "Settings" -> "Configure digikam..." -> "Metadata" ->
"Behaviour"

you have also to define explicitly which (meta)data are to be written,
it's not a « write all » feature. The Settings Metadata folder displays
several checkboxes for different data items, Title and description,
and/or Rating, and/or Tagslist, etc.

It's up to you to check/unckeck item by item, what you wish to be
written and what you prefer not to be. If you haven't check Save
image tags, DK will never write them.

Note also that in that same configuration folder, if you set the
Metadata writing mode to « Write to image only » , or « image and
sidecar file » , you won't need any more to activate the « Write
metadata to image » , it will be done each time you modify something,
the title, rating, tags, etc., without manual intervention.



About metadata being read by other applications :

It's not a simple issue because some metadata fields are more or less
standard across applications, and some other are not. To write your
image title and description, DK uses standard XMP fields, in the
Dublin Core namespace, and these could be read by other applications.

As for Dolphin, Peter answered :

The part of viewing the tags in dolphin belongs to the topic
"semantic desktop" of KDE. "Nepomuk" is another term related with
this.

Official site: http://nepomuk.kde.org/

NB: some images viewers, e.g. Gwenview, are more images oriented and can
display almost all metadata fields. DK tags appear with Gwenview.

However, tagslist as featured in DK have a hierarchical structure and
this is not fully supported in basic standards. So, DK saves the
information into an application dedicated namespace,
<digiKam:TagsList>, but only Digikam is supposed to be able to read
that. To increase the probability some other applications could read
the info, Digikam saves also tagslist information in several other
metadata fields, hierarchicalSubject, Keywords, Subject.
Maybe other...

This is a nice idea for increased potential interoperability, but has
two side effects :

- Some information may disappear. E.g. the standard Keywords or
Subject metadata fields format supports only a flat list of keywords,
not a hierarchical structure.
So if you have a structured tag on an image,
say /Location/France/Paris, only the tail component Paris will appear
as a keyword and another application reading metadata will no longer
be aware of the former hierarchy.

(As far as I know, only the hierarchicalSubject field ensures
compatibilty with Adobe software, without structure loss.)


- This mechanism may overwrite some standard fields if you use other
metadata edition programs. E.g. editing image title and description
will keep compatibility with DK, but image subject edition would be
destroyed the next time DK saves a tagslist.
(I'm sure of that, I've already lost subjects:-)

And this is why defining item by item what is to be written, in the
Metadata settings folder, cf. supra, is a nice feature. (This is my
personal case; I save titles and descriptions, but as I happen to edit
also subjects of my own, I don't save tagslists not to destroy my
subjects. But it's a detail.)


Regards,
Jean-François

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Digikam-users mailing list
[hidden email]
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