Optimal wallpaper dimensions for scaled displays?

[dukee101]

If I have a 4K display scaled to 2560x1440, what should the dimensions of my wallpapers be if I want the crispest background possible? Will 2560x1440 wallpapers look as crisp as the scaled UI on a 4K monitor with native dimensions of 3840x2160? Or should I strive to download 3840x2160 wallpapers?

 

[dukee101]

I ran some experiments to answer my own question. I've concluded that images with a resolution higher than the scaled resolution will look crisper/sharper. For example: on a 5K display scaled to 1440p, using 5K resolution wallpapers will look better than 1440p wallpapers, even though 1440p would be 1:1 at that scale. In other words, wallpaper crispness/sharpness is not actually being scaled, from what I gather.