SUMMARY

Folder View (/Desktop) generates poor image previews -- but only for landscape images.

I.e., for the case that the with of the image is bigger than its height, the corresponding thumbnail gets exremely "unsharp". Square or landscape images look satisfactorily, though.

Please see attached screenshot (also showing a comparison with Dolphin).


STEPS TO REPRODUCE

1. Put an image having landscape size on your Desktop (e.g. a common photo, ratio 4:3) 
2. Put another image with portrait properties on your Desktop or make a copy of the first one and cut it to portrait (e.g. ratio 2:3)


OBSERVED RESULT

First image looks unsharp. Second image looks fine.


EXPECTED RESULT

Both images look sharp.


SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Debian GNU/Linux & KDE Neon Unstable Edition

KDE Plasma Version: 1.14.5 & 1.17.80
KDE Frameworks Version: 5.54.0 & 5.62.0
Qt Version: 5.11.3 & 5.13.1


ADDITIONAL INFORMATION

Related (resolved) bugs:
https://bugs.kde.org/show_bug.cgi?id=355592
https://bugs.kde.org/show_bug.cgi?id=376848