Bug 494302

Summary:	Add a new thumbnails creation option not based based on embedded Exif preview but on the full image data.
Product:	[Applications] digikam	Reporter:	Paul Krause <paul_krause_1980>
Component:	Thumbs-Image	Assignee:	Digikam Developers <digikam-bugs-null>
Status:	REPORTED ---
Severity:	wishlist	CC:	caulier.gilles
Priority:	NOR
Version First Reported In:	8.5.0
Target Milestone:	---
Platform:	Appimage
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Paul Krause 2024-10-08 17:38:23 UTC

SUMMARY
Digikam creates thumbnails for Jxl images based on the embedded Exif metadata preview (if any exists).
The user cannot change this behavior.
Depending on the Exif metadata, the thumbnail thus might be wrong, e.g. outdated.

STEPS TO REPRODUCE
0. Make Digikam thumbnail some Jxl image. E.g.:
1. Start appimage on a clean system
2. Select a folder with Jxl images containing Exif preview image

OBSERVED RESULT
Digikam creates the thumbnails from the Exif metadata thumbnail/preview.

EXPECTED RESULT
Have an option, entry in the config file or similar to create the thumbnails from the main image.

ADDITIONAL INFORMATION
Thumbnails for Jpg images, and probably other formats, are created from the main image.
Full log on request.
Last relevant line appears to be:
Digikam::ThumbnailCreator::crateThumbnail: (...) from Embedded preview with Exiv2

SOFTWARE/OS VERSIONS
digiKam-8.5.0-20241007T160120-Qt6-x86-64.appimage
Also appears on other versions of the 8.X series

Comment 1 caulier.gilles 2024-10-09 05:00:38 UTC

Hi,

Why to use Exif preview if exists to render thumbnails ? For performance reasons of course, to prevent to decode whole image which can take age.

If exif preview is not updated by 3rdparty software it's not the digiKam fault at all. 3rdparty software must be fixed. This is the how the interroperability works between application. digiKam update the Exif preview after editing an image.

Best

Gilles Caulier