[digiKam-users] Digikam puts its "signature" in metadata even when no other changes - why?

[Chris Green]

I have my main album installed on two systems and, after doing some
changes to metadata on one system, I copied the image files to the
other system.  Well 'copied' is a misnomer, it's still doing it after
several hours.

I took a look to see why and discovered that Digikam has written its
current version into the metadata of every single image, since I have
around 30000 images that makes for a *lot* of file copying!  It also
means that file modification dates are all changed for no particular
reason.

Why does Digikam do this?  I don't really care what software has been
used to do things to my images, at least I don't want it written in to
the metadata.  Also it writes the Digikam version so even changing
Digikam version will cause an update of every file in the album.

Is there any way of turning this off?


--
Chris Green
·

[woenx]

I don't know about the "signature", other software does the same thing.
However, disabling the option to update the timestamp (Settings, Configure
digikam, Metadata, "update filestamp when files are modified) on every
picture it's the first thing I do when I install digikam. I lost lots of
dates that were not saved to the metadata (the original date when the
picture was taken) because of that.

I guess the signature is only written to files that have been modified.
Which is all of them in your case.

I don't know why it's not disabled by default.



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[Chris Green]

woenx <[hidden email]> wrote:
> I don't know about the "signature", other software does the same thing.

Other software doing the same thing doesn't necessarily make it a good
idea! :-)


> However, disabling the option to update the timestamp (Settings, Configure
> digikam, Metadata, "update filestamp when files are modified) on every
> picture it's the first thing I do when I install digikam. I lost lots of
> dates that were not saved to the metadata (the original date when the
> picture was taken) because of that.
>
My pictures are stored in a year/month/day hierarchy so their
directory tells me their date.  Relying on the file creation or
modification date as the 'picture' date isn't a good idea IMHO.
I need to rely on that date to ensure the right files get copied to
the other system (using rsync).


> I guess the signature is only written to files that have been modified.
> Which is all of them in your case.
>
I didn't modify all of them, it's quite difficult to do something that
modifies 30 thousand files!  I probably made changes that I wanted to
do to a few hundred files.  I just wanted those files copied to the
other system.


> I don't know why it's not disabled by default.
>
Yes, it may be something that some people want to do but I would have
thought that most people *don't* want it.

--
Chris Green
·

[Jack Marxer]

I think that the option to update the timestamp (Settings, Configure

> digikam, Metadata, "update filestamp when files are modified") 

SHOULD BE DISABLED BY DEFAULT.

I just saw this today and am very sorry that I didn't notice it before.

On Thu, Sep 20, 2018 at 11:16 PM Chris Green <[hidden email]> wrote:

woenx <[hidden email]> wrote:
> I don't know about the "signature", other software does the same thing.

Other software doing the same thing doesn't necessarily make it a good
idea! :-)


> However, disabling the option to update the timestamp (Settings, Configure
> digikam, Metadata, "update filestamp when files are modified) on every
> picture it's the first thing I do when I install digikam. I lost lots of
> dates that were not saved to the metadata (the original date when the
> picture was taken) because of that.
>
My pictures are stored in a year/month/day hierarchy so their
directory tells me their date.  Relying on the file creation or
modification date as the 'picture' date isn't a good idea IMHO.
I need to rely on that date to ensure the right files get copied to
the other system (using rsync).


> I guess the signature is only written to files that have been modified.
> Which is all of them in your case.
>
I didn't modify all of them, it's quite difficult to do something that
modifies 30 thousand files!  I probably made changes that I wanted to
do to a few hundred files.  I just wanted those files copied to the
other system.


> I don't know why it's not disabled by default.
>
Yes, it may be something that some people want to do but I would have
thought that most people *don't* want it.

--
Chris Green
·

[Remco Viëtor]

On vendredi 21 septembre 2018 10:22:54 CEST Jack Marxer wrote:
> I think that the option to update the timestamp (Settings, Configure
>
> > digikam, Metadata, "update filestamp when files are modified")
>
> SHOULD BE DISABLED BY DEFAULT.
> I just saw this today and am very sorry that I didn't notice it before.
>

No need to yell, it won't replace factual arguments...

And i disagree, as a default, the "file modified" timestamp should be updated
when files are, well, modified.

At least for me, the expected behaviour for the "modification" timestamp is to
reflect the last time the file was modified, Anything else would be surprising.
And one of the principles of deciding what should be the default is that it
should be the least surprising behaviour.

That modification timestamp helps when you want to collect a number of edits,
or need to remove sidecars: just order by timestamp in a file manager, and
you'll have all the original files together. That means there's less risk of
deleting an original image file.

Don't forget that the image metadata contain the original date the image was
created (i.e. the shutter was pressed). That one should never be touched
automatically (and isn't, afaik), and manually only for a good reason (e.g.
camera clock was wrong).

Remco

[Remco Viëtor]

On jeudi 20 septembre 2018 23:07:42 CEST Chris Green wrote:
> woenx <[hidden email]> wrote:
> > I don't know about the "signature", other software does the same thing.
>
> Other software doing the same thing doesn't necessarily make it a good
> idea! :-)
>
But it does allow the software to see what kind of fields can be expected in
the metadata, and how to interpret them.

And if there's information about the processing,  the program and version that
created that information is really needed to make sure any replay can be done
correctly. Different programs, and sometimes even different versions, can use
different algorithms or interpret parameters differently. No information about
creating program/version would make storing processing info useless: no
reliable way to reuse it, and it is not really human-readable (you see the
numbers, but you'll have no idea what they mean).

Remco

[woenx]

But, for instance, let's say I tag a picture with the tag "dog". Is it really
necessary to include which software has tagged it, the version, and update
the modification (or creation) date?

Specially the last thing. Some older digital cameras did not store the date
in EXIF metadata, and the only date was the file date. After digikam scanned
my whole collection, all dates were changed to that day's date, so I lost
quite a big of information.



--
Sent from: http://digikam.1695700.n4.nabble.com/digikam-users-f1735189.html

[Remco Viëtor]

On vendredi 21 septembre 2018 12:00:00 CEST woenx wrote:
> But, for instance, let's say I tag a picture with the tag "dog". Is it
> really necessary to include which software has tagged it, the version, and
> update the modification (or creation) date?
>
> Specially the last thing. Some older digital cameras did not store the date
> in EXIF metadata, and the only date was the file date. After digikam scanned
> my whole collection, all dates were changed to that day's date, so I lost
> quite a big of information.

I agree that there are situations where it's not the right thing to do. And
for those cases it is nice if the program can be set to not updating the
timestamp.

But this was about what to use as a *default*. And I maintain that the default
should be "when modifying a file, set the modification timestamp to the time of
the modificiation".

Oh, and when the dates were changed after *scanning* the collection, you might
want to file a bug report. Scanning should not modify the files or their
timestamps (as it's only reading the files). But do make sure that it was
indeed just a pure scan.

Remco

[Chris Green]

Remco Viëtor <[hidden email]> wrote:

> On jeudi 20 septembre 2018 23:07:42 CEST Chris Green wrote:
> > woenx <[hidden email]> wrote:
> > > I don't know about the "signature", other software does the same thing.
> >
> > Other software doing the same thing doesn't necessarily make it a good
> > idea! :-)
> >
> But it does allow the software to see what kind of fields can be expected in
> the metadata, and how to interpret them.
>

Possibly, but how many programs are there out there that 'understand'
how Digikam uses the metadata?


> And if there's information about the processing,  the program and version that
> created that information is really needed to make sure any replay can be done
> correctly. Different programs, and sometimes even different versions, can use
> different algorithms or interpret parameters differently. No information about
> creating program/version would make storing processing info useless: no
> reliable way to reuse it, and it is not really human-readable (you see the
> numbers, but you'll have no idea what they mean).
>
Yes, but in reality my images have been processed by several different
programs.  Say I do major image enhancement/changes using Gimp or
Photoshop, then some changes to metadata using Photini and then I use
Digikam to manage the inmages.  Having 'Digikam 5.9' in the metadata
would be totally misleading!

Also Digikam writes 'Digikam 5.9' into the metadata even when it
hasn't changed anything else at all.

--
Chris Green
·

[PackElend]

Also Digikam writes 'Digikam 5.9' into the metadata even when it
hasn't changed anything else at all.

totally agree, there should be some kind of differentiation 

On 21.09.2018 13:12, Chris Green wrote:

Remco Viëtor [hidden email] wrote:

On jeudi 20 septembre 2018 23:07:42 CEST Chris Green wrote:

woenx [hidden email] wrote:

I don't know about the "signature", other software does the same thing.

Other software doing the same thing doesn't necessarily make it a good
idea! :-)

But it does allow the software to see what kind of fields can be expected in 
the metadata, and how to interpret them. 

Possibly, but how many programs are there out there that 'understand'
how Digikam uses the metadata?

And if there's information about the processing,  the program and version that 
created that information is really needed to make sure any replay can be done 
correctly. Different programs, and sometimes even different versions, can use 
different algorithms or interpret parameters differently. No information about 
creating program/version would make storing processing info useless: no 
reliable way to reuse it, and it is not really human-readable (you see the 
numbers, but you'll have no idea what they mean).

Yes, but in reality my images have been processed by several different
programs.  Say I do major image enhancement/changes using Gimp or
Photoshop, then some changes to metadata using Photini and then I use
Digikam to manage the inmages.  Having 'Digikam 5.9' in the metadata
would be totally misleading!

Also Digikam writes 'Digikam 5.9' into the metadata even when it
hasn't changed anything else at all.

[Maik Qualmann]

Ok, interesting discussion. If I look at the definition of Exiv2:

Exif.Image.ProcessingSoftware => The name and version of the software used to
post-process the picture.

Would I understand it so that only with changes to the image data is a
software entry. So I would suggest that only the image editor sets the
software entries, but also the lossless JPEG rotation. Metadata changes write
no digiKam software entrys.

Maik

Am Freitag, 21. September 2018, 13:28:04 CEST schrieb Stefan Müller:

> Also Digikam writes 'Digikam 5.9' into the metadata even when it
> hasn't changed anything else at all.
> totally agree, there should be some kind of differentiation
>
>
> On 21.09.2018 13:12, Chris Green wrote:
>
> Remco Viëtor <[hidden email]> wrote:
>
> On jeudi 20 septembre 2018 23:07:42 CEST Chris Green wrote:
>
> woenx <[hidden email]> wrote:
>
> I don't know about the "signature", other software does the same thing.
>
> Other software doing the same thing doesn't necessarily make it a good
> idea! :-)
>
>
> But it does allow the software to see what kind of fields can be expected in
> the metadata, and how to interpret them.
>
>
> Possibly, but how many programs are there out there that 'understand'
> how Digikam uses the metadata?
>
>
>
> And if there's information about the processing,  the program and version
> that created that information is really needed to make sure any replay can
> be done correctly. Different programs, and sometimes even different
> versions, can use different algorithms or interpret parameters differently.
> No information about creating program/version would make storing processing
> info useless: no reliable way to reuse it, and it is not really
> human-readable (you see the numbers, but you'll have no idea what they
> mean).
>
>
> Yes, but in reality my images have been processed by several different
> programs.  Say I do major image enhancement/changes using Gimp or
> Photoshop, then some changes to metadata using Photini and then I use
> Digikam to manage the inmages.  Having 'Digikam 5.9' in the metadata
> would be totally misleading!
>
> Also Digikam writes 'Digikam 5.9' into the metadata even when it
> hasn't changed anything else at all.

[Maik Qualmann]

https://cgit.kde.org/digikam.git/commit/?
id=f969875cb3a9ff70e927364f5d406229505b70fd

Maik

Am Freitag, 21. September 2018, 21:43:36 CEST schrieben Sie:

> Ok, interesting discussion. If I look at the definition of Exiv2:
>
> Exif.Image.ProcessingSoftware => The name and version of the software used
> to post-process the picture.
>
> Would I understand it so that only with changes to the image data is a
> software entry. So I would suggest that only the image editor sets the
> software entries, but also the lossless JPEG rotation. Metadata changes
> write no digiKam software entrys.
>
> Maik
>
> Am Freitag, 21. September 2018, 13:28:04 CEST schrieb Stefan Müller:
> > Also Digikam writes 'Digikam 5.9' into the metadata even when it
> > hasn't changed anything else at all.
> > totally agree, there should be some kind of differentiation
> >
> >
> > On 21.09.2018 13:12, Chris Green wrote:
> >
> > Remco Viëtor <[hidden email]> wrote:
> >
> > On jeudi 20 septembre 2018 23:07:42 CEST Chris Green wrote:
> >
> > woenx <[hidden email]> wrote:
> >
> > I don't know about the "signature", other software does the same thing.
> >
> > Other software doing the same thing doesn't necessarily make it a good
> > idea! :-)
> >
> >
> > But it does allow the software to see what kind of fields can be expected
> > in the metadata, and how to interpret them.
> >
> >
> > Possibly, but how many programs are there out there that 'understand'
> > how Digikam uses the metadata?
> >
> >
> >
> > And if there's information about the processing,  the program and version
> > that created that information is really needed to make sure any replay can
> > be done correctly. Different programs, and sometimes even different
> > versions, can use different algorithms or interpret parameters
> > differently.
> > No information about creating program/version would make storing
> > processing
> > info useless: no reliable way to reuse it, and it is not really
> > human-readable (you see the numbers, but you'll have no idea what they
> > mean).
> >
> >
> > Yes, but in reality my images have been processed by several different
> > programs.  Say I do major image enhancement/changes using Gimp or
> > Photoshop, then some changes to metadata using Photini and then I use
> > Digikam to manage the inmages.  Having 'Digikam 5.9' in the metadata
> > would be totally misleading!
> >
> > Also Digikam writes 'Digikam 5.9' into the metadata even when it
> > hasn't changed anything else at all.

[Chris Green]

Maik Qualmann <[hidden email]> wrote:

> Ok, interesting discussion. If I look at the definition of Exiv2:
>
> Exif.Image.ProcessingSoftware => The name and version of the software used to
> post-process the picture.
>
> Would I understand it so that only with changes to the image data is a
> software entry. So I would suggest that only the image editor sets the
> software entries, but also the lossless JPEG rotation. Metadata changes write
> no digiKam software entrys.
>

Yes, I think that would be my take on it too.  Something that changes
the metadata really shouldn't be leaving its 'fingerprint' behind.


--
Chris Green
·

[Rafael Linux]

I understand that Digikam writes to sidecar what he needs to write, and no
more. GIMP does it
In fact, as someone, wrote here, Digikam does NOT write to sidecar while
scanning. If so, I should noticed it each time I launch Digikam, with a
+300K photos database like mine, cause it will be writing to sidecars in the
disk. However, my case
(http://digikam.1695700.n4.nabble.com/digiKam-users-Anyone-with-a-300K-photos-internal-mysql-database-td4706440.html)
is not related with sidecars (at first sight).



--
Sent from: http://digikam.1695700.n4.nabble.com/digikam-users-f1735189.html