Comment 17 for bug 259181

Shouldn't the image be formatted to the smallest screen height/width ratio you expect, then stretched to 100% of the screen width and the height scaled the same and cropped?

To cover 4:3, 16:10 and 16:9 screens, you'd format the image 4:3 and set width = "100%" height="scale".

That would not work for screens taller than they are wide (rotated monitors for instance), but formatting the image to 9:16, putting the original image in the middle and filling the open areas at the top and bottom would handle all screens from 9:16 to 16:9. As far as I can tell, this is how the scale and crop wallpaper position works.

You would have to reformat the background used with the splash screen to match. RIght now it seems to be scaling both dimensions to 100%, which would cause a shift in aspect ratio on anything but a 16:10 screen (I think?)