Post a screenshot of your Desktop

[Terminal Velocity]

I had the same issue but with a background that was a design rather than a photo and I was able to stretch it without too much trouble. The envane background that was used in one of the old DSL 3.x releases - I stretched it until the rectangular bits were 1920x1080 then pasted the original round center part back in w/o distortion.

Wouldn't want to try that with your background, though.

Cinnamon has an option to stretch the wallpaper, so you don't have to edit the image and it is stretching very well, I found out yesterday

 

[GatorsFan]

Expirion Xfce based on Devuan

 

[truckerDave]

I just found in some old backups my longest lasting wallpaper, I used it for years, I thought to share it and backup it also in here. Unfortunately it is old CRT aspect ratio and don't appear full size in modern screens, but is an exceptional image worth having in your collections
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It might be worth a shot trying out one of the A.I. bots out there. A few of those can do some pretty neat stuff with lower resolutions and what have ya.