Wallpapers larger than display dimensions won't adjust

I used to be able to get large wallpapers to adjust according to the desktop settings (fill screen, fit to screen, stretch to fill screen, and center), but now whatever setting they're on, they always show up as if set to "fill screen." Is there a way to make those settings work on larger wallpapers like they do on smaller ones?

about my mac:

OSX Mountain Lion 10.8.5

Display set to 1280 x 800