Bug 434594 - copy of jpeg file with empty caption (but caption in sidecar) shows caption
Summary: copy of jpeg file with empty caption (but caption in sidecar) shows caption
Status: RESOLVED INTENTIONAL
Alias: None
Product: digikam
Classification: Applications
Component: Metadata-Sidecar (show other bugs)
Version: 7.1.0
Platform: Microsoft Windows Microsoft Windows
: NOR minor
Target Milestone: ---
Assignee: Digikam Developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-03-18 17:55 UTC by Christopher Partington
Modified: 2021-03-18 20:59 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In: 7.2.0
Sentry Crash Report:


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Description Christopher Partington 2021-03-18 17:55:56 UTC
SUMMARY
With digikam configured to write metadata to sidecar files only,
add caption to jpeg, copy jpeg file but not sidecar (outside digikam). New
file has caption.

STEPS TO REPRODUCE
1. Configure digikam as follows:
Settings->Configure->metadata->Behaviour
.Write to metadata
..Image tags
..Captions and title
..Timestamps
..Geolocation info
.Reading and writing metadata
..Update file modification
..Rescan when files modified
Settings->Configure->metadata->Sidecars 
.Read from sidecar files
.Write to sidecar files
.Write to XMP sidecar only
.Sidecar file names are compatible with commercial programs

2. Outside digikam, create new jpeg (screen capture) and save to existing
album folder
3. Use exiftool to check nothing odd in the jpeg file
4. In digikam change caption (creates sidecar file)
5. Use exiftool to verify jpeg file has not been changed
6. Outside digikam, copy jpeg file - but not xmp file - to new name in
same folder
7. digikam finds new image but shows caption same as the original,
even though there is no matching sidecar file
8. Use exiftool to verify that no caption has been written to either
jpeg file

OBSERVED RESULT
Digikam shows same caption for new file as old file, even though it
doesn't have a sidecar file or embedded caption.

EXPECTED RESULT
Empty caption.

SOFTWARE/OS VERSIONS
Windows: 10

ADDITIONAL INFORMATION
I'm not sure if this should be higher priority. While I appreciate that
it's a contrived situation, it's putting me off making a complete switch
to digikam until I understand why this has happened and whether it can
happen under other image-importing situation.
Comment 1 Maik Qualmann 2021-03-18 20:36:33 UTC
This is not a bug, but intentional behavior ...
digiKam recognizes the image again during the scan, based on the unique hash in the database. It is therefore the same image, which is why all metadata in the database (including the captions, tags labels, etc.) is also applied to this picture. So has nothing to do with sidecar. If users rename or move pictures externally, digiKam must recognize the picture, otherwise the metadata would be lost.

Maik
Comment 2 Christopher Partington 2021-03-18 20:42:31 UTC
(In reply to Maik Qualmann from comment #1)
> This is not a bug, but intentional behavior ...
> digiKam recognizes the image again during the scan, based on the unique hash
> in the database. It is therefore the same image, which is why all metadata
> in the database (including the captions, tags labels, etc.) is also applied
> to this picture. So has nothing to do with sidecar. If users rename or move
> pictures externally, digiKam must recognize the picture, otherwise the
> metadata would be lost.
> 
> Maik

Brilliant! Thank you for that. For a brief moment, I did wonder if something like that was going on but decided it was unlikely. I did have a good nose around looking for something like this to explain it but drew a blank. Thank you again for the explanation and I'm sorry to have taken up your time.
Comment 3 Maik Qualmann 2021-03-18 20:59:41 UTC
Another note, the digiKam-7.2.0 version is about to be released, as Windows users you should test this version, more than 350 bugs have been closed. Windows support has also been further improved. The version can be downloaded here:

https://files.kde.org/digikam/
https://files.kde.org/digikam/digiKam-7.2.0-20210317T200949-Win64.exe

Maik