Writing metadata to image files

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Writing metadata to image files

spinsheet
I am a bit of a novice user of photo library software and as such have some basic questions. I do not quite understand what the 'Tools' > 'Write metadata to all images' option does. My assumption is that it does just what it says, but I'm not sure of the details. What are the implications? Does it write ALL of the metadata to the images (tags, comments, copyright, etc.)? Are other photo library applications now able to see the metadata associated with the images? If the metadata is written to the images themselves, is there still a purpose to the database file that DigiKam uses? Are there performance implications to doing this? Is there a way to have DigiKam write these metadata to the images as it is entered or must the tools option be used every so often to write it?

One reason for my asking is that I would like to use DigiKam on the network, allowing many people to have read access to the images and everyone seeing the same tags, if these metadata where written to the images themselves, this might accomplish that.

Thanks,
Todd
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Re: Writing metadata to image files

Julien Narboux
spinsheet a écrit :
> I am a bit of a novice user of photo library software and as such have some
> basic questions. I do not quite understand what the 'Tools' > 'Write
> metadata to all images' option does. My assumption is that it does just what
> it says, but I'm not sure of the details. What are the implications? Does it
> write ALL of the metadata to the images (tags, comments, copyright, etc.)?
> Are other photo library applications now able to see the metadata associated
> with the images?
Yes, all other applications which supports EXIF, IPCT ...
> If the metadata is written to the images themselves, is
> there still a purpose to the database file that DigiKam uses?
Yes, for performance and for people who do not want to write the
metadata in the pictures and for picture format which can not contain
metadata.
> Are there
> performance implications to doing this? Is there a way to have DigiKam write
> these metadata to the images as it is entered or must the tools option be
> used every so often to write it?
>  
Yes, it is an option, look in the preferences. It is also a question of
the first time wizard when you lunch digikam for the first time.

Hope this helps.

Julien


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Re: Writing metadata to image files

Vlado Plaga
In reply to this post by spinsheet
Most questions have already been answered by Julien, so here comes just
some additional information.

'Write metadata to all images' basically does the same as 'Album/ Write
metadata to images' and 'Image/ Write metadata to selected images', they
only apply this to different sets of imagesm AND there is a bug in
'Write metadata to all images' (digiKam 0.10 to digiKam 1.0), which
should be fixed in following releases:
https://bugs.kde.org/show_bug.cgi?id=220202

Also note that all these write options only write the part of the
metadata you selected in the preferences, if I'm not mistaken. I simply
selected pretty much everything. Then you can indeed restore digiKam's
database completely from the metadata read from the images. Of course
you still need the database for quick selection of sets of images (e.g.
all five star images with a specific tag).

Regards,
Vlado
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Re: Writing metadata to image files

spinsheet
Thanks, this is all quite informative. I do have some additional questions

In 'Preferences' > 'Metadata' I see 'Common Metadata Actions', which of those choices writes the metadata to the actual image files themselves? The only one that I see that obviously writes metadata to the files is 'Write Metadata to RAW files (experimental)', I assume that that is not the one as I am not dealing with RAW files and it's also experimental.

If I set this up on a network drive and write the metadata to the images, will others be able to do searches based on tags or will they only be able to see the tags associated with an image and not be able to actually do a search based on those tags? Will DigiKam build a database file based on the embedded metadata? As I do not want others to have write access to the images, will they be able to create their own custom tags that only reside on their machine and not in the images (I would imagine that this is true)?

Thanks.

Bugzilla from rechner@vlado-do.de wrote
Most questions have already been answered by Julien, so here comes just
some additional information.

'Write metadata to all images' basically does the same as 'Album/ Write
metadata to images' and 'Image/ Write metadata to selected images', they
only apply this to different sets of imagesm AND there is a bug in
'Write metadata to all images' (digiKam 0.10 to digiKam 1.0), which
should be fixed in following releases:
https://bugs.kde.org/show_bug.cgi?id=220202

Also note that all these write options only write the part of the
metadata you selected in the preferences, if I'm not mistaken. I simply
selected pretty much everything. Then you can indeed restore digiKam's
database completely from the metadata read from the images. Of course
you still need the database for quick selection of sets of images (e.g.
all five star images with a specific tag).

Regards,
Vlado
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Re: Writing metadata to image files

Julien Narboux
spinsheet a écrit :
> Thanks, this is all quite informative. I do have some additional questions
>
> In 'Preferences' > 'Metadata' I see 'Common Metadata Actions', which of
> those choices writes the metadata to the actual image files themselves? The
> only one that I see that obviously writes metadata to the files is 'Write
> Metadata to RAW files (experimental)', I assume that that is not the one as
> I am not dealing with RAW files and it's also experimental.
>
>  

You need to check the five first items of  "Common Metadata Actions".
Shift F1 on the option clarify what it does.

By the way, dear developpers,  I think the description of these options
is not very clear, I understand the confusion
of spinsheet.

 I would write :
"Save image caption as metadata embedded in files" instead of
"Save image caption as embedded text"

"Save image tags as metadata "Keywords" embedded in files" instead of
"Save image tags as "Keywords" tags"

Maybe there could be a label to explain the five first settings,
something saying:
"Which pieces of information do you want to save as (EXIF, IPCT, XMP)
metadata embedded into files.

> If I set this up on a network drive and write the metadata to the images,
> will others be able to do searches based on tags or will they only be able
> to see the tags associated with an image and not be able to actually do a
> search based on those tags? Will DigiKam build a database file based on the
> embedded metadata? As I do not want others to have write access to the
> images, will they be able to create their own custom tags that only reside
> on their machine and not in the images (I would imagine that this is true)?
>
>  
Unfortunately, other people will have to use the "Album/ Reread metadata
From Images" action in their copy of DigiKam  each time you are updating
the metadata...

In development branch of Digikam
(branches/extragear/graphics/digikam/1.0-databaseext), Holger Foerster
is working on a full database support for Digikam (Digikam currently
only use sqlite, a small embedded database). This support may allow in
the future to have a real framework for managing metadata  in Digikam
from several computers.  But I guess it will take a lots of time before
it appears in a stable release (I think it is also a feature which is
missing in major software such as Lightroom).

Julien


> Thanks.
>
>
> Bugzilla from [hidden email] wrote:
>  
>> Most questions have already been answered by Julien, so here comes just
>> some additional information.
>>
>> 'Write metadata to all images' basically does the same as 'Album/ Write
>> metadata to images' and 'Image/ Write metadata to selected images', they
>> only apply this to different sets of imagesm AND there is a bug in
>> 'Write metadata to all images' (digiKam 0.10 to digiKam 1.0), which
>> should be fixed in following releases:
>> https://bugs.kde.org/show_bug.cgi?id=220202
>>
>> Also note that all these write options only write the part of the
>> metadata you selected in the preferences, if I'm not mistaken. I simply
>> selected pretty much everything. Then you can indeed restore digiKam's
>> database completely from the metadata read from the images. Of course
>> you still need the database for quick selection of sets of images (e.g.
>> all five star images with a specific tag).
>>
>> Regards,
>> Vlado
>> _______________________________________________
>> Digikam-users mailing list
>> [hidden email]
>> https://mail.kde.org/mailman/listinfo/digikam-users
>>
>>
>>    
>
>  

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Re: Writing metadata to image files

Gilles Caulier-4
2010/1/11 Julien Narboux <[hidden email]>:

> spinsheet a écrit :
>> Thanks, this is all quite informative. I do have some additional questions
>>
>> In 'Preferences' > 'Metadata' I see 'Common Metadata Actions', which of
>> those choices writes the metadata to the actual image files themselves? The
>> only one that I see that obviously writes metadata to the files is 'Write
>> Metadata to RAW files (experimental)', I assume that that is not the one as
>> I am not dealing with RAW files and it's also experimental.
>>
>>
>
> You need to check the five first items of  "Common Metadata Actions".
> Shift F1 on the option clarify what it does.
>
> By the way, dear developpers,  I think the description of these options
> is not very clear, I understand the confusion
> of spinsheet.
>
>  I would write :
> "Save image caption as metadata embedded in files" instead of
> "Save image caption as embedded text"
>
> "Save image tags as metadata "Keywords" embedded in files" instead of
> "Save image tags as "Keywords" tags"
>
> Maybe there could be a label to explain the five first settings,
> something saying:
> "Which pieces of information do you want to save as (EXIF, IPCT, XMP)
> metadata embedded into files.
>
>> If I set this up on a network drive and write the metadata to the images,
>> will others be able to do searches based on tags or will they only be able
>> to see the tags associated with an image and not be able to actually do a
>> search based on those tags? Will DigiKam build a database file based on the
>> embedded metadata? As I do not want others to have write access to the
>> images, will they be able to create their own custom tags that only reside
>> on their machine and not in the images (I would imagine that this is true)?
>>
>>
> Unfortunately, other people will have to use the "Album/ Reread metadata
> From Images" action in their copy of DigiKam  each time you are updating
> the metadata...
>
> In development branch of Digikam
> (branches/extragear/graphics/digikam/1.0-databaseext), Holger Foerster
> is working on a full database support for Digikam (Digikam currently
> only use sqlite, a small embedded database).

MySql is used in this branch.

>This support may allow in
> the future to have a real framework for managing metadata  in Digikam
> from several computers.  But I guess it will take a lots of time before
> it appears in a stable release (I think it is also a feature which is
> missing in major software such as Lightroom).


Probalbly with digiKam 1.3 release.

Gilles
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Re: Writing metadata to image files

spinsheet
In reply to this post by Julien Narboux
This all sounds very doable then. So as long as any of the users uses the 'Reread metadata from images' option then their local database is synced up with the embedded metadata that is associated with the images? With about 1,000 images that task is taking about 15 mins when I do it on my computer (everything is local at this point). That is a significant amount of time but I also assume that they will only have to do it when they actually want the most recent metadata and not necessarily every time that they want to look at the images.

While this is not a perfect network solution it seems to me that it will serve our purposes. Do you see anything that I may have missed that might be a deal breaker for this? I really do like DigiKam and would like very much to integrate it in our organization. Being a non-profit the price is certainly right.

Thanks.
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Re: Writing metadata to image files

Vlado Plaga
In reply to this post by Julien Narboux
Am Mon, 11 Jan 2010 08:12:51 +0100
schrieb Julien Narboux <[hidden email]>:

> spinsheet a écrit :

> > Will DigiKam
> > build a database file based on the embedded metadata?

Yes, if digiKam finds a new picture with metadata that data is
included. I sometimes even found it annoying, getting pictures from
"outside" that already have descriptions and thus suddenly having new
tags in my tag tree.

> > As I do not
> > want others to have write access to the images, will they be able
> > to create their own custom tags that only reside on their machine
> > and not in the images (I would imagine that this is true)?

Yes, each digiKam from a different user (or on a different system) can
have its own database. Either the others configure their digiKam to not
write tags to images, or you simply don't give them write access to the
image files.

> Unfortunately, other people will have to use the "Album/ Reread
> metadata From Images" action in their copy of DigiKam  each time you
> are updating the metadata...

I also find this annoying, since I'm using digiKam with two different
configurations (from Linux and Mac OS) for the same set of pictures. I
thought I'd just let the two digiKam versions have their own database
and "sync" them by importing from metadata written to the pictures, but
this does not work.

As Stibbons writes in feature request #173632:

"The problem here is when updating the picture with an external tool,
changes in iptc comment are not reflected in digikam database."

https://bugs.kde.org/show_bug.cgi?id=173632

There is an answer by Marcel Wiesweg explaining this behaviour:

"When detecting a change of modification date, only 'hard' information
is rescanned, that is file size, fingerprint, dimension, format, bit
depth and color model.
The rationale is that digikam gives priority to what is stored in its
database. If you edit photos with an external tool, you need to take
the extra step and run the sync-with-db tool."

I think an option "Re-read metadata when files are modified", possibly
with an additional "Picture metadata overrides database information"
would be very useful. After all a picture with a modified file date
could IMHO just be handled like a new file - but of course changing
digiKam's default behaviour now would be counter-productive. That's why
new options would be nice. I might file a feature request for this soon,
but will leave the suggestion on the mailing list for a few days first.
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