[Digikam-users] [KPhotoAlbum] User experience (or bugs, hopes and wishes)

[Gilles Caulier]

On Monday 02 October 2006 13:58, Robert L Krawitz wrote:
>    Date: Mon, 02 Oct 2006 19:58:22 +0900
>    From: "Birkir A. Barkarson" <birkirb at stoicviking.net>
>
>    This is my first posting to the mailing list. It is mainly intended
>    for the Digikam mailing list as that is what I am currently using
>    but I cross post this to the KPhotoAlbum list as well since I like
>    their interface and it is my hope that they will adopt similar way
>    to store metadata in-tag like digikam does.  My apologies if this
>    is offends or is not welcomed.
>
> Just to be fair, there are also disadvantages to storing metadata in
> the images:
>
> 1) Any time the original image files are modified there's a risk of
>    corrupting them.
>
> 2) It doesn't work if the images are physically stored on a read-only
>    medium.
>
> 3) Updating many images is likely to be very slow (the image file will
>    likely have to be resized to add or remove metadata, which will
>    result in the entire file having to be rewritten).  For example, I
>    tagged 3500 images totaling 25 GB from a recent vacation.

This is not true about JPEG. Only JFIF, EXIF and IPTC section are rewritten. 
The image data are untouched.

Later, i will implement in Exiv2 the same thing about PNG to write metadata on 
the fly without decoding/encoding image data. About TIFF, Andreas (Exiv2 
coordinator)  will implemente the TIFF-EP/RAW file metadata writting on the 
fly using the same rules.

>
> 4) Some cameras can sign images to later verify that they have not
>    been modified (e. g. for use as evidence in court).  Depending upon
>    exactly what the signature covers, modifying the image file may
>    destroy the signature.

If sign is in metadata, well yes something can be lost. I suspect than 
Makernotes are used for that. Since Exiv2 Makernotes support have been 
improved with the last stable release, i think than this problem is now 
limited.

If sign is a watermark embedded into image data, we don't change these data 
during metatada update.

>
> 5) It's much harder to implement undo across sessions or versioning if
>    the metadata is stored in the images.
>
> I actually rather like the database and "do not modify the original
> image file" myself, and it's a big reason why I use KPhotoAlbum.

In digiKam you has the choise : database only, database+pictures. Look in 
metadata setup tab.

Gilles Caulier