https://bugs.kde.org/show_bug.cgi?id=455876
Bug ID: 455876
Summary: Handling of image orientation in modern image formats
Product: digikam
Version: 7.7.0
Platform: unspecified
OS: All
Status: REPORTED
Severity: normal
Priority: NOR
Component: Metadata-Orientation
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 150112
--> https://bugs.kde.org/attachment.cgi?id=150112&action=edit
Test image in JPEG XL format
Hello,
digiKam rotates images images according orientation in Exif metadata. That's
how it must be done for old JPG format.
However, JPEG XL, HEIF, AVIF have rotation stored inside the format and if
there is any orientation in the Exif metadata, it is not longer relevant (it
refers just to the source/input image prior encoding).
The best handling of these formats it is to ignore rotations in Exif metadata.
"The Exif orientation should be ignored by applications; the JPEG XL codestream
orientation takes precedence and libjxl will by default apply the correct
orientation automatically"
https://github.com/libjxl/libjxl/blob/b7961e1318634a95c7d689ec340dbad8a42d4ed4/lib/include/jxl/decode.h#L1251
However, in some cases, there could be Thumbnail in JXL file stored in Exif
metadata. If you are reading the Thumbnail, it must be still rotated according
the Exif orientation.
The attached image (IMG_20220406_134135.jxl) is now rotated in digiKam, but the
preview is OK. Correct display is without rotation and to keep rotation of the
Exif thumbnail according the Exif.
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