Found this valuable information on the web, Miles' patch works very well for me.
If you use Miles Baders transparent emacs branch (currently only available via arch) you can make the buffer have a variety of different image backgrounds. Example 
It's possible to use the wallpaper pixmap directly, but I'd recommend processing the wallpaper image a bit in the Gimp first - in this case I dilated it and blurred it. This means it won't distract you from your work.
To get the branch of emacs that supports this, get a copy of tla installed (see gnuarch.org) and run:
$ tla register-archive email@example.com http://firstname.lastname@example.org
$ tla get email@example.com/emacs--tiling
Then build it in the normal way (hint: enabling gtk2 makes it look nicer too).
In order to enable transparent emacs, you have to add these lines in your ~/.emacs file :
(custom-set-faces '(default ((t (:stipple nil :background ((image :type jpeg :file "/Path/to/your/image.png") :origin display) :foreground "white" :inverse-video nil :box nil :strike-through nil :overline nil :underline nil :slant normal :weight normal :height 101 :width normal :family "misc-fixed")))))
You could also configure transparent background like that in Emacs without modify your configuration file by hand :
M-x customize-face → default → Background → Value Menu → 1 = Image → File (path)
Then you could Save for Future Sessions to save this configuration in you ~/.emacs file.