How can I change my desktop background with python?

On Windows with python2.5 or higher, use ctypes to load user32.dll and call SystemParametersInfo() with SPI_SETDESKWALLPAPER action.

For example:

import ctypes
SPI_SETDESKWALLPAPER = 20 
ctypes.windll.user32.SystemParametersInfoA(SPI_SETDESKWALLPAPER, 0, "image.jpg" , 0)

For Python3.5, SystemParametersInfoA doesn't work. Use SystemParametersInfoW.

import ctypes
ctypes.windll.user32.SystemParametersInfoW(20, 0, "absolute path" , 0)

On a gnome desktop, you usually do this with gconf, either directly calling gconftool or using the gconf python module. The latter is in the link given by unutbu. The first method could be done like this.

import commands
command = "gconftool-2 --set /desktop/gnome/background/picture_filename --type string '/path/to/file.jpg'"
status, output = commands.getstatusoutput(command)  # status=0 if success

On windows, you will need some trickery with pywin32, and the windows API, on 'linux' the answer will depend on which desktop is running - KDE, Gnome, or something more exotic. Under KDE (and maybe Gnome) you can probably send a message using D-Bus, which you could do without including any new libraries by using the command line tool dbus-send.

The other option would be to set the desktop wallpaper to a file which you then edit / replace from python - but this will probably only result in a change when the user logs in.

Firstly, import ctypes: it gives you access to windows components such as the screensaver, wallpapers, etc.

Then call

ctypes.windll.user32.SystemParametersInfoA(20, 0, the_complete_path_of_your_image, 0)

Make sure the path is the complete path of your image, not just the path from the active directory

import ctypes,win32con

def getWallpaper():
    ubuf = ctypes.create_unicode_buffer(512)
    ctypes.windll.user32.SystemParametersInfoW(win32con.SPI_GETDESKWALLPAPER,len(ubuf),ubuf,0)
    return ubuf.value

def setWallpaper(path):
    changed = win32con.SPIF_UPDATEINIFILE | win32con.SPIF_SENDCHANGE
    ctypes.windll.user32.SystemParametersInfoW(win32con.SPI_SETDESKWALLPAPER,0,path,changed)

Alternatively: (with SystemParametersInfoA)

def getWallpaper():
    sbuf = ctypes.create_string_buffer(512) # ctypes.c_buffer(512)
    ctypes.windll.user32.SystemParametersInfoA(win32con.SPI_GETDESKWALLPAPER,len(sbuf),sbuf,0)
    return sbuf.value

def setWallpaper(path):
    changed = win32con.SPIF_UPDATEINIFILE | win32con.SPIF_SENDCHANGE
    ctypes.windll.user32.SystemParametersInfoA(win32con.SPI_SETDESKWALLPAPER,0,path.encode(),changed) # "".encode() = b""

Arguments are:
SystemParametersInfo(SetOrGet, GetBufferSize, SetBufferOrGetBuffer, SetChange)

The path has to be absolute, so if you're using something relative to your script, do:
path = os.path.abspath(path)

To see more stuff you can do with SystemParametersInfo, see the docs.
(near the bottom there's an example to change the mouse speed)

P.S. There are many answers already here, but they're leaving out the broadcasting you're supposed to do. Sure it works without it, but it's bad practice not to use it properly.

P.P.S And they only gave hard coded values, rather than the variables they come from.

Also note, i use 512 characters for the buffer size when getting the path, just to be more safe since paths might exceed 256. I doubt anyone will have paths as long as that though.

One more note. I've only tested the above examples in Python 3, but i don't think SystemParametersInfoA needs the .encode() in Python 2. (they updated strings in Python 3 to unicode i believe) The string in SystemParametersInfoW may need converting for Python 2.

I read all the answers and after searching for a while i found a easier solution.

Install the module named py-wallpaper.

pip install py-wallpaper

Import the module.

from wallpaper import set_wallpaper, get_wallpaper

set the wallpaper using set walpaper

set_wallpaper("location/to/image.jpg")

get the current wallpaper's path using get wallpaper

print(get_wallpaper())

thanks.

On Windows with python2.5 or higher, use ctypes to load user32.dll and call

import ctypes
ctypes.windll.user32.SystemParametersInfoW(20,0,"Path_wallpaper", 0) 
     speak("Background changed succesfully")

Just adding a small precision to ShivaGuntuku 's post : In python 3 you should replace the 'A' by a 'W' in SytemParametersInfoA. Small exemple to change your desktop background in windows10 with python 3 :

import ctypes
import os
SPI_SETDESKWALLPAPER = 20
ctypes.windll.user32.SystemParametersInfoW(
    SPI_SETDESKWALLPAPER, 0, 'C:\\Users\\godet\\OneDrive\\Images\\breaker_wall.jpg', 0)