[digiKam-users] Confused by tick boxes in "Edit Metadata" + how does "Captions" interact?

[Chris Green]

This is all on Digikam 5.6 running in xubuntu 18.04.

Firstly the tick-boxes in "Edit Metadata".  Each item you can edit has
a tick box, what does it do?  Does it simply mean "you can change this
item", does it mean that the item gets written to metadata when you
click "Apply" or "OK", or what does it mean?

There are also the three extra tick boxes which I assume are the ones
that copy metadata between Exif, IPTC and XMP.  However there is some
confusion here too (for me anyway!), what is JFIF?  After some
experimentation it seems that Exif Comment means Exif Caption and that
when the 'sync' tick-box is ticked then whenever an item is *changed*
then the corresponding other metadata is synchronised.  This can be a
bit confusing if, for example, "Sync Exif Comment" is ticked for both
XMP and IPTC.

Also how does the "Captions" section of the sidebar interact with
all the above?


What would also be really, really useful would be a listing of which
Exif, IPTC and XMP fields correspond to each field in the "Edit
Metadata" section as this would clear up any ambiguity between
"Comment", "Caption", "Description" and similar.  Either this or give
the actual field names in the "Edit Metadata", e.g. you could put

Caption (Exif.Photo.UserComment):



Finally (yes, I know there are lots of questions here) when changing
an item does it get written to both database and image on both "Apply"
and "Exit" if one has ticked all the boxes in "Write this information
to the Metadata"?


--
Chris Green
·

[Gilles Caulier-4]

2018-09-16 17:39 GMT+02:00 Chris Green <[hidden email]>:

This is all on Digikam 5.6 running in xubuntu 18.04.

Firstly the tick-boxes in "Edit Metadata".  Each item you can edit has
a tick box, what does it do?  Does it simply mean "you can change this
item", does it mean that the item gets written to metadata when you
click "Apply" or "OK", or what does it mean?

Checking a section enable change in metadata relevant when Apply is pressed. That all.

 

There are also the three extra tick boxes which I assume are the ones
that copy metadata between Exif, IPTC and XMP.  However there is some
confusion here too (for me anyway!), what is JFIF? 

JPEG segment used to store comment and more. Look in wikipedia.

https://en.wikipedia.org/wiki/JPEG_File_Interchange_Format. This is not Exif.

And yes, photo file format are puzzle...

 

After some
experimentation it seems that Exif Comment means Exif Caption and that
when the 'sync' tick-box is ticked then whenever an item is *changed*
then the corresponding other metadata is synchronised.  This can be a
bit confusing if, for example, "Sync Exif Comment" is ticked for both
XMP and IPTC.

Also how does the "Captions" section of the sidebar interact with
all the above?

When you change something in metadata editor, DK will scan the image metadata and sync back the database.

This will sync the right sidebar tab.

 

What would also be really, really useful would be a listing of which
Exif, IPTC and XMP fields correspond to each field in the "Edit
Metadata" section as this would clear up any ambiguity between
"Comment", "Caption", "Description" and similar.  Either this or give
the actual field names in the "Edit Metadata", e.g. you could put

In fact no. This tool try to simplify the complixity of reduntant metadat tags in files, something like the file properties in Photoshop.

 

Caption (Exif.Photo.UserComment):



Finally (yes, I know there are lots of questions here) when changing
an item does it get written to both database and image on both "Apply"
and "Exit" if one has ticked all the boxes in "Write this information
to the Metadata"?

yes

Gilles Caulier

[Chris Green]

Gilles Caulier <[hidden email]> wrote:

[snip]
> >
> > There are also the three extra tick boxes which I assume are the ones
> > that copy metadata between Exif, IPTC and XMP.  However there is some
> > confusion here too (for me anyway!), what is JFIF?
>
> JPEG segment used to store comment and more. Look in wikipedia.
>
Ah, OK, thank you.

> https://en.wikipedia.org/wiki/JPEG_File_Interchange_Format. This is not
> Exif.
>
> And yes, photo file format are puzzle...
>
Absolutely!  It's all a bit of a can of worms and I realise that
Digikam is doing its best to handle it all in a reasonable way.

[snip]

> >
> > What would also be really, really useful would be a listing of which
> > Exif, IPTC and XMP fields correspond to each field in the "Edit
> > Metadata" section as this would clear up any ambiguity between
> > "Comment", "Caption", "Description" and similar.  Either this or give
> > the actual field names in the "Edit Metadata", e.g. you could put
> >
> >
> In fact no. This tool try to simplify the complixity of reduntant metadat
> tags in files, something like the file properties in Photoshop.
>

OK, but it would still be very useful to be able to find this
information.  I know some are described in detail in the
Metadata->Advanced tab in Settings but it would be good to know how
all are handled.  Maybe the section in Settings could be extended?

Anyway, thank you for your reply, I know this is a rather 'messy' area
in handling image files so there is no easy answer.


--
Chris Green
·

[Remco Viëtor]

On lundi 17 septembre 2018 09:21:13 CEST Chris Green wrote:

> Gilles Caulier <[hidden email]> wrote:
>
> [snip]
>
> > > There are also the three extra tick boxes which I assume are the ones
> > > that copy metadata between Exif, IPTC and XMP.  However there is some
> > > confusion here too (for me anyway!), what is JFIF?
> >
> > JPEG segment used to store comment and more. Look in wikipedia.
>
> Ah, OK, thank you.
>
> > https://en.wikipedia.org/wiki/JPEG_File_Interchange_Format. This is not
> > Exif.
> >
> > And yes, photo file format are puzzle...
>
> Absolutely!  It's all a bit of a can of worms and I realise that
> Digikam is doing its best to handle it all in a reasonable way.
>
> [snip]
>
> > > What would also be really, really useful would be a listing of which
> > > Exif, IPTC and XMP fields correspond to each field in the "Edit
> > > Metadata" section as this would clear up any ambiguity between
> > > "Comment", "Caption", "Description" and similar.  Either this or give
> > > the actual field names in the "Edit Metadata", e.g. you could put
> >
> > In fact no. This tool try to simplify the complixity of reduntant metadat
> > tags in files, something like the file properties in Photoshop.
>
> OK, but it would still be very useful to be able to find this
> information.  I know some are described in detail in the
> Metadata->Advanced tab in Settings but it would be good to know how
> all are handled.  Maybe the section in Settings could be extended?
>
> Anyway, thank you for your reply, I know this is a rather 'messy' area
> in handling image files so there is no easy answer.

Part of the problem for the XMP part is that Digikam tries to keep some
compatibility with other programs. That means that some tag contents have to
be duplicated over different XML tags. Worse, those tags can change without
warning, as Digikam has no control over what those other programs do.

Depending on what you plan on doing with that information, you may or may not
have to take into account all the different tags that store keywords. Best
might be to take an image with typical (or worst-case) tagging and create a
full dump of the metadata with exiftool or exiv2 (or both). That should show
you how those tags are handled.

Or open an XMP sidecar file in a text editor, it's just a plain text file
containing an XML tag structure (it's not XML, as it's missing the required
headers). Working with the XML files is probably safer than working on image
files in any case (and faster, as the files are a lot smaller).

Remco

[Chris Green]

Remco Viëtor <[hidden email]> wrote:

> > > > What would also be really, really useful would be a listing of which
> > > > Exif, IPTC and XMP fields correspond to each field in the "Edit
> > > > Metadata" section as this would clear up any ambiguity between
> > > > "Comment", "Caption", "Description" and similar.  Either this or give
> > > > the actual field names in the "Edit Metadata", e.g. you could put
> > >
> > > In fact no. This tool try to simplify the complixity of reduntant metadat
> > > tags in files, something like the file properties in Photoshop.
> >
> > OK, but it would still be very useful to be able to find this
> > information.  I know some are described in detail in the
> > Metadata->Advanced tab in Settings but it would be good to know how
> > all are handled.  Maybe the section in Settings could be extended?
> >
> > Anyway, thank you for your reply, I know this is a rather 'messy' area
> > in handling image files so there is no easy answer.
>
> Part of the problem for the XMP part is that Digikam tries to keep some
> compatibility with other programs. That means that some tag contents have to
> be duplicated over different XML tags. Worse, those tags can change without
> warning, as Digikam has no control over what those other programs do.
>
> Depending on what you plan on doing with that information, you may or may not
> have to take into account all the different tags that store keywords. Best
> might be to take an image with typical (or worst-case) tagging and create a
> full dump of the metadata with exiftool or exiv2 (or both). That should show
> you how those tags are handled.
>

Yes, this is what I aim to do, I was just hoping that there might be
an easier way! :-)

--
Chris Green
·