Changing the Lock Screen Wallpaper in Lubuntu

I noticed that after changing my desktop wallpaper in Lubuntu 13.10 "saucy" (right click on the desktop and choose Desktop Preferences, Appearance tab), that the image on my lock screen had not changed. I don't love that wallpaper, so I wanted to change it. After searching the web and not finding a way to do so, I tried a few things and finally ran a locate for "wallpaper" finding, among other things, these files:

dave@tyrant:~$ locate wallpaper
(output has been truncated to display only relevant files)
/usr/share/lubuntu/wallpapers
/usr/share/lubuntu/wallpapers/1310-A_Winter_Magic_by_Luciash_D-Being.jpg
/usr/share/lubuntu/wallpapers/1310-Moody_by_Robert_Wicek.jpg
/usr/share/lubuntu/wallpapers/1310-Muelle_by_Manuel_Puentes.jpg

Listing the contents of that directory gave me a little more insight:

dave@tyrant:~$ cd /usr/share/lubuntu/wallpapers
dave@tyrant:/usr/share/lubuntu/wallpapers$ ls -l
total 5260
-rw-r--r-- 1 root root  890508 Sep 19 11:57 1310-A_Winter_Magic_by_Luciash_D-Be
ing.jpg
-rw-r--r-- 1 root root  585583 Sep 19 14:41 1310-lubuntu-default-wallpaper.png
-rw-r--r-- 1 root root  370825 Sep 19 11:57 1310-Moody_by_Robert_Wicek.jpg
-rw-r--r-- 1 root root  461580 Sep 19 11:57 1310-Muelle_by_Manuel_Puentes.jpg
-rw-r--r-- 1 root root  835281 Sep 19 11:57 1310-Smolikas_by_George_Blades_Voul
garakis.jpg
-rw-r--r-- 1 root root 2175372 Sep 19 11:57 1310-Two_Jack_Lake_by_C_Ayers.jpg
lrwxrwxrwx 1 root root      29 Feb 11 12:49 lubuntu-default-wallpaper.jpg ->
lubuntu-default-wallpaper.png
lrwxrwxrwx 1 root root      12 Feb 22 10:54 lubuntu-default-wallpaper.png ->
./1310-lubuntu-default-wallpaper.png

So, I copied the picture I wanted as my wallpaper into this directory and re-established what seemed to be the operative link:

dave@tyrant:/usr/share/lubuntu/wallpapers$ sudo su - # be careful after this as
we are now root
root@tyrant:~# cd /usr/share/lubuntu/wallpapers
root@tyrant:/usr/share/lubuntu/wallpapers# cp /home/dave/unnecessarily_long_web
_name.jpg ./nifty_colors.jpg
root@tyrant:/usr/share/lubuntu/wallpapers# ln -fs ./nifty_colors.jpg ./lubuntu-
default-wallpaper.png
root@tyrant:/usr/share/lubuntu/wallpapers# exit
logout
dave@tyrant:/usr/share/lubuntu/wallpapers$

And it worked! Using this method I have a different wallpaper on my desktop than on my lock screen, which is also cool.