Dolphin fails to generate thumbnails for images with more than 32 bits per pixel (across various formats). See duplicate reports for concrete examples
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A possibly relevant merge request was started @ https://invent.kde.org/network/kio-extras/-/merge_requests/341
Git commit c169a773cc55466417198847a9b6328df6cd4250 by Nicolas Fella. Committed on 21/03/2024 at 19:51. Pushed by nicolasfella into branch 'master'. [thumbnail] Limit bits per pixel to 32 PreviewJob allocates shared memory for transferring the thumbnail data. There it assumes max. 32 bits per pixel Now when we load an image with 64 bpp we fail to send it because not enough memory was allocated To avoid this convert the image to a 32bit format if neccesary For a small thumbnail we don't really need that much color bits anyway M +2 -1 thumbnail/thumbnail.cpp https://invent.kde.org/network/kio-extras/-/commit/c169a773cc55466417198847a9b6328df6cd4250
Git commit fe1b4b23c38cbf5c37625ef43fd732e2afaf1084 by Nicolas Fella. Committed on 22/03/2024 at 11:00. Pushed by nicolasfella into branch 'release/24.02'. [thumbnail] Limit bits per pixel to 32 PreviewJob allocates shared memory for transferring the thumbnail data. There it assumes max. 32 bits per pixel Now when we load an image with 64 bpp we fail to send it because not enough memory was allocated To avoid this convert the image to a 32bit format if neccesary For a small thumbnail we don't really need that much color bits anyway (cherry picked from commit c169a773cc55466417198847a9b6328df6cd4250) M +2 -1 thumbnail/thumbnail.cpp https://invent.kde.org/network/kio-extras/-/commit/fe1b4b23c38cbf5c37625ef43fd732e2afaf1084
Is it really a matter of memory ? I can save a 16 bit tiff with 290 kiB and still no thumbnail is created.
It doesn't matter how small or large the image is. The code allocates exactly as much memory as it needs for the image, but while doing it it assumes that 32 bit/4bytes are needed per pixel. See https://invent.kde.org/frameworks/kio/-/blob/master/src/gui/previewjob.cpp?ref_type=heads#L802
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