[digiKam-users] Lossless rotate & auto-rotate

SDX sdx at inbox.lv
Thu Feb 25 07:26:48 GMT 2021


Hello, I have read through lots of documentation and could not find a
definitive answer IF and when DigiKam 7.2 uses lossless Jpeg rotation? 
If I rotate a JPG file, it all the time changes file size, so it probably is
NOT lossless?
Also DigiKam is not on the list here: http://jpegclub.org/losslessapps.html 

1 - is normal "Rotate Left/Right" lossless for JPG files? (it seems to be
no)
2 - is "Auto Rotate/Flip Using Exif information" lossless?

Because of the known issue that Windows Photo Gallery does not understand
rotation tags, I would like to fix all photos using "Auto Rotate/Flip Using
Exif information", but if DigiKam can not do it losslessly, then there
should be a confirmation dialog to stop people from messing up their photos.


Note, I also noticed that after DigiKam writes metadata to JPEG files from
Panasonic camera, the file becomes a few KB smaller. This is very strange as
DigiKam presumable wrote more metadata to it than Windows Photo Gallery and
yet the file becomes smaller... Scary stuff.



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