metadata menu and configure options

[Elle Stone]

Hi, all,

I have some questions about image metadata, digikam options, and
information in the database.

1. What controls what metadata gets written to the database  during
image import?

2. What affect (if any) does changes in Menu/Settings/Configure
digiKam/Metadata have on what metadata goes into the database? Is all
the information displayed in the Metadata left side panel also in the
database? Or just some of it?

3. Under Menu/Album there are two options: "Write Metadata to Images"
and "Reread Metadata from Images". I know those sound
self-explanatory, but what really happens? When might one want (or not
want) to use either of these alternatives? Is it safe to assume that
writing metadata to a raw file is still not advised, even if possible
(putting dng aside - I don't use dng)? I'm doing a little tag-pruning,
so would it be wise to write the updated tags back to the jpegs? How
about tiff? png? ppm? Is there a list somewhere of supported file
formats?

Many thanks for help in sorting this out.

Elle Stone
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[Elle Stone]

Regarding my questions 1 and 2 above, it appears that digiKam presets (over which the user has no control) control what metadata gets saved to the database.

To ascertain this, I created two test databases, in one of which I added checkmarks to a whole lot of additional metadata, from the Menu/configure digikam/metadata tabs. Then I inspected the resulting databases using SQLite database browser. In both databases (using the same set of images), the metadata in the database was the same.

A lot of the database entries are empty and likely always will be empty, given my camera/lens combination. Other metadata that (perhaps - I'm still experimenting) I would like to have include in the database, apparently can't be optionally included by the user?

So is my conclusion correct,  that the metadata digiKam saves to the database is preset, giving no options for user configuration?

Elle Stone

[Micha? Smoczyk]

On 05.01.2011 00:47, Elle Stone wrote:

> 3. Under Menu/Album there are two options: "Write Metadata to Images"
> and "Reread Metadata from Images". I know those sound
> self-explanatory, but what really happens? When might one want (or not
> want) to use either of these alternatives? Is it safe to assume that
> writing metadata to a raw file is still not advised, even if possible
> (putting dng aside - I don't use dng)? I'm doing a little tag-pruning,
> so would it be wise to write the updated tags back to the jpegs? How
> about tiff? png? ppm? Is there a list somewhere of supported file
> formats?

I am curious what is the difference between those two options, too.

--
/\/\ichau, admin [malpka] nocnyrzepin [kropa] net
http://www.nocnyrzepin.net


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[Marcel Wiesweg]

> I have some questions about image metadata, digikam options, and
> information in the database.
>
> 1. What controls what metadata gets written to the database  during
> image import?

Any metadata for which we have a field in the database will be read.
Regard the database as a cache in that respect.

>
> 2. What affect (if any) does changes in Menu/Settings/Configure
> digiKam/Metadata have on what metadata goes into the database?

This for writing to a file only

> Is all
> the information displayed in the Metadata left side panel also in the
> database? Or just some of it?

The Metadata tab reads from the file only. The summary properties tab e.g. is
fed from the db.

>
> 3. Under Menu/Album there are two options: "Write Metadata to Images"
> and "Reread Metadata from Images". I know those sound
> self-explanatory, but what really happens?

Reread -> Full rescan as if the file was scanned for the first time
Write -> Write from db to file, according to options

> When might one want (or not
> want) to use either of these alternatives? Is it safe to assume that
> writing metadata to a raw file is still not advised, even if possible
> (putting dng aside - I don't use dng)?

Will depend on the individual raw file type

> I'm doing a little tag-pruning,
> so would it be wise to write the updated tags back to the jpegs?

Yes. Doing this automatically is a TODO

> How
> about tiff? png? ppm? Is there a list somewhere of supported file
> formats?

Jpg, Tiff Png have of course first-class support. Dont know if PPM supports
metadata. We use libexiv2: www.exiv2.org there'll be a list

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[Gilles Caulier-4]

2011/1/11 Marcel Wiesweg <[hidden email]>

> I have some questions about image metadata, digikam options, and
> information in the database.
>
> 1. What controls what metadata gets written to the database  during
> image import?

Any metadata for which we have a field in the database will be read.
Regard the database as a cache in that respect.

>
> 2. What affect (if any) does changes in Menu/Settings/Configure
> digiKam/Metadata have on what metadata goes into the database?

This for writing to a file only

> Is all
> the information displayed in the Metadata left side panel also in the
> database? Or just some of it?

The Metadata tab reads from the file only. The summary properties tab e.g. is
fed from the db.

>
> 3. Under Menu/Album there are two options: "Write Metadata to Images"
> and "Reread Metadata from Images". I know those sound
> self-explanatory, but what really happens?

Reread -> Full rescan as if the file was scanned for the first time
Write -> Write from db to file, according to options

> When might one want (or not
> want) to use either of these alternatives? Is it safe to assume that
> writing metadata to a raw file is still not advised, even if possible
> (putting dng aside - I don't use dng)?

Will depend on the individual raw file type

> I'm doing a little tag-pruning,
> so would it be wise to write the updated tags back to the jpegs?

Yes. Doing this automatically is a TODO

> How
> about tiff? png? ppm? Is there a list somewhere of supported file
> formats?

Jpg, Tiff Png have of course first-class support. Dont know if PPM supports
metadata. We use libexiv2: www.exiv2.org there'll be a list

PPM only support on comment field limited to 256 char if i remember. No more. Forget this format to play with photo.

Note : metadata image limitation can be dropped with XMP sidecar support implemented in 2.0.0

Gilles Caulier

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