In this day and age, many people use multi screens in their setup. I’m one of those people. One thing that really bugs me in OS X however, is that you cannot set one wallpaper to expand beyond one screen.
Let’s say you have two screens with 1920×1080 resolution and you have found a wallpaper of the appropriate dimension (ie. 3840×1080). Interfacelift got plenty of them.
Now, in order to properly use these, you need to slice the image into two images (one for each screen). Sure, you can do this in Photoshop, but that feels like an overkill.
convert source.jpg -crop 1920x1080 sliced.jpg
And voilá — you know got two images. One for each screen:
That wasn’t very hard, was it? If you have screens of different resolutions, that is a bit trickier, but ImageMagick should still be able to do it.