https://bugs.kde.org/show_bug.cgi?id=420710
--- Comment #22 from Stefan <thaqe9rd...@temp.mailbox.org> ---
(In reply to MarcP from comment #19)
> In any case, according to that conversion table:
>
> Exif.Image.DateTime <=> Xmp.xmp.ModifyDate
>
> That means that the Exif.Image.DateTime, that is used in digikam as the date
> for when the "picture was taken" and currently syncs with Xmp.xmp.CreateDate
> is indeed a "last modification date", and it's used like that in most
> pictures managers. That field will be overwritten as soon as a picture is
> edited, so that field should not be used to store permanent data.
>
> The other equivalency:
>
> Exif.Photo.DateTimeOriginal <=> Xmp.photoshop.DateCreated
>
> is a bit weird. But in any case, that speaks against the use of
> Xmp.xmp.CreateDate in digikam and use Xmp.photoshop.DateCreated instead.
> Actually, that is the case for Adobe Lightroom, Adobe Photoshop, and ACDSee.
> However, Xmp.exif.DateTimeOriginal is the preferred field for that
> information in Picasa, ACDSee, and Shotwell. For some reason, Microsoft
> Photos just uses the xmp.xmp.createdate field instead, like Digikam (and
> also Shotwell, but not exclusively).
>
>
> (Oh, and more argument for the use of Exif.Photo.DateTimeOriginal as the
> main "Date taken" field in Exif, is that most (if not all) cameras store the
> date in that field, while not using any kind of XMP information.
A complicated subject, which is probably not always clearly implemented in
other (commercial) software.
In DigiKam-DB there are two fields for this data: In the table
"imageinformation" the fields "creationDate" and "digitizationDate". These
fields are equivalent to the Exif fields "9003 (Exif.Photo.DateTimeOriginal)"
and "9004 (Exif.Photo.DateTimeDigitized)" from the digital cameras. According
to exiv2 the fields "Xmp.photoshop.DateCreated (9003)" and "Xmp.xmp.CreateDate
(9004)" are assigned to these two fields during conversion.
So there should be no discrepancies, no matter how the data is moved back and
forth:
9003 Exif.Photo.DateTimeOriginal => imageinformation.creationDate =>
Xmp.photoshop.DateCreated
9004 Exif.Photo.DateTimeDigitized => imageinformation.digitizationDate =>
Xmp.xmp.CreateDate
But how are all the date fields used in the Metadata Editor? There are 7 fields
in total (8 with video date):
Exif
Creation date
Original date
Digitization date
IPTC
Digitization date
Creation date
XMP
Digitization date
Creation date
Video date
There is also a date field under "Labels - Description". This field alone fills
"imageinformation.creationDate".
Then following the logic from above only the fields
"Exif.Photo.DateTimeOriginal" = "Xmp.photoshop.DateCreated" would use this
date.
However, in the metadata editor all fields except the field "XMP Digitization
Date" are filled with this value ("imageinformation.creationDate").
If I now change the value in the field "XMP Digitization Date" in the Metadata
Editor, I expect this value to be transferred to the field
"imageinformation.digitizationDate". But in "imageinformation.digitizationDate"
the value from "imageinformation.creationDate" is written.
How can I change the date in "imageinformation.digitizationDate"?
But what also happens: the digitization date is written correctly in the
sidecar file in "exif:DateTimeDigitized". But the value "xap:CreateDate" is
wrong (="exif:DateTimeOriginal")
If now the photo has no metadata in the image or as a sidecar file - nothing is
displayed under "Metadata". This means that the digicam does not save the
metadata.
The field "imageinformation.creationDate" is displayed as "Camera creation
date" in the "View - Preview Images", also under "Captions - Description". What
is the field "imageinformation.digitizationDate" for then?
And why can I fill 7 date fields in the Metadata Editor - whereas in reality 6
fill the same field ("imageinformation.creationDate") and also store the same
value as various metadata (*) - and only one field ("XMP Digitization Date")
stores another metadata field ("exif:DateTimeDigitized")? It does not matter if
I enter different values for Exif/IPTX/XMP and also deselect "Match values":
Only one date ("imageinformation.creationDate") is written into all fields.
(*) exif:DateTimeOriginal, tiff:DateTime, xmp:CreateDate, xmp:MetadataDate,
xmp:ModifyDate, video:DateTimeOriginal, video:DateUTC, video:ModificationDate,
photoshop:DateCreated
*** Translated with www.DeepL.com/Translator (free version) ***
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