---

$code = @'
using System;
using System.Runtime.InteropServices;
public class Wallpaper {
    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    public static extern int SystemParametersInfo(int uAction, int uParam, string lpvParam, int fuWinIni);
}
'@
Add-Type $code
[Wallpaper]::SystemParametersInfo(20, 0, "C:\Folder\image.jpg", 3)