Setting the desktop background image via Powershell

Question

UPDATE: 
I found the solution that addressed my problem, which I posted in a post below. Keeping the original post for Internet historical reasons as I the hope this helps someone else later on in their search for a solution. 
===============
I have Bing'ed and I have Google'd and I haven't found a solid answer to setting the desktop wallpaper programmically.  I am trying to do this via PowerShell, but I would be happy for any other language flavor or application to work. 
Below is the code I have tried to set the desktop background image. This has been scrounged from a few sources across the web. This solution works 25% of the time and I haven't figured out what the cause for success or failure of the execution. Or maybe
it's neither, but waiting for Explorer to refresh. The only way to see the change 100% is to log out and log back in.
I am running Windows 8.1 btw. 
Thank you for looking.
Function Get-WallPaper()
$wp=Get-ItemProperty -path 'HKCU:\Control Panel\Desktop\' -name wallpaper
if(!$wp.WallPaper)
{ "Wall paper is not set" }
Else
{"Wall paper is set to $($wp.WallPaper)" }
Function Refresh-Explorer {
$code = @'
private static readonly IntPtr HWND_BROADCAST = new IntPtr(0xffff);
private const int WM_SETTINGCHANGE = 0x1a;
private const int SMTO_ABORTIFHUNG = 0x0002;
[System.Runtime.InteropServices.DllImport("user32.dll", SetLastError=true, CharSet=CharSet.Auto)]
static extern bool SendNotifyMessage(IntPtr hWnd, uint Msg, UIntPtr wParam,
IntPtr lParam);
[System.Runtime.InteropServices.DllImport("user32.dll", SetLastError = true)]
private static extern IntPtr SendMessageTimeout ( IntPtr hWnd, int Msg, IntPtr wParam, string lParam, uint fuFlags, uint uTimeout, IntPtr lpdwResult );
[System.Runtime.InteropServices.DllImport("Shell32.dll")]
private static extern int SHChangeNotify(int eventId, int flags, IntPtr item1, IntPtr item2);
public static void Refresh() {
SHChangeNotify(0x8000000, 0x1000, IntPtr.Zero, IntPtr.Zero);
SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, IntPtr.Zero, null, SMTO_ABORTIFHUNG, 100, IntPtr.Zero);
Add-Type -MemberDefinition $code -Namespace MyWinAPI -Name Explorer
[MyWinAPI.Explorer]::Refresh()
Function Set-WallPaper($Value)
echo "Setting background to: $value"
Refresh-Explorer
Set-ItemProperty -path 'HKCU:\Control Panel\Desktop\' -name wallpaper -value $value
rundll32.exe user32.dll, UpdatePerUserSystemParameters
#sleep 1
rundll32.exe user32.dll, UpdatePerUserSystemParameters
#sleep 1
rundll32.exe user32.dll, UpdatePerUserSystemParameters
#sleep 1
Refresh-Explorer
#Stop-Process -ProcessName explorer
NOTE: I left in a few commented out statements. I found that they do not offer any help in formulating a solution.
Thank you.

Answer 1

Great news! I found the solution and all props and credit goes to
jsd1982 of the XKCD comic
forum from a post he made in 2007 and some deep search kung-fu Googling on my part. Here is the
direct link to the post.
This solution has worked for me 100% of the time on Windows 8. The only gotcha I found (minor detail) was when setting this process to run as a scheduled task, I had to run it as elevated privileges for the code to compile in memory. Running this function
from PowerShell at the command prompt was fine. 
NOTE: The code below is a slight trimmed down version posted by jsd1982 to just set the desktop wallpaper. I removed the image fetching from the Internet and the color inversion.
# Credit to jsd1982
function Compile-Csharp ([string] $code, $FrameworkVersion="v2.0.50727",
[Array]$References)
# Get an instance of the CSharp code provider
$cp = new-object Microsoft.CSharp.CSharpCodeProvider
# Build up a compiler params object...
$framework = [System.IO.Path]::Combine($env:windir, "Microsoft.NET\Framework\$FrameWorkVersion")
$refs = new-object Collections.ArrayList
$refs.AddRange( @("${framework}\System.dll",
# "${mshhome}\System.Management.Automation.dll",
# "${mshhome}\System.Management.Automation.ConsoleHost.dll",
"${framework}\system.windows.forms.dll",
"${framework}\System.data.dll",
"${framework}\System.Drawing.dll",
"${framework}\System.Xml.dll"))
if ($references.Count -ge 1)
$refs.AddRange($References)
$cpar = New-Object System.CodeDom.Compiler.CompilerParameters
$cpar.GenerateInMemory = $true
$cpar.GenerateExecutable = $false
$cpar.CompilerOptions = "/unsafe";
$cpar.OutputAssembly = "custom"
$cpar.ReferencedAssemblies.AddRange($refs)
$cr = $cp.CompileAssemblyFromSource($cpar, $code)
if ( $cr.Errors.Count)
$codeLines = $code.Split("`n");
foreach ($ce in $cr.Errors)
write-host "Error: $($codeLines[$($ce.Line - 1)])"
$ce |out-default
Throw "INVALID DATA: Errors encountered while compiling code"
[System.Reflection.Assembly]::LoadWithPartialName("System.Drawing") > $null
[System.Reflection.Assembly]::LoadWithPartialName("System.Runtime") > $null
# C# code to post to wallpaper
$code = @'
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.IO;
using System.Net;
using Microsoft.Win32;
namespace test
public class Wallpaper
const int SPI_SETDESKWALLPAPER = 20 ;
const int SPIF_UPDATEINIFILE = 0x01;
const int SPIF_SENDWININICHANGE = 0x02;
[DllImport("user32.dll", CharSet=CharSet.Auto)]
static extern int SystemParametersInfo (int uAction , int uParam , string lpvParam , int fuWinIni) ;
public static void SetWallpaper(string uri)
System.IO.Stream s = new WebClient().OpenRead(uri);
Image img = System.Drawing.Image.FromStream(s);
Bitmap copy = new Bitmap(img.Width, img.Height);
Graphics g = Graphics.FromImage(copy);
Rectangle rect = new Rectangle(0, 0, img.Width, img.Height);
g.DrawImage(img, rect, 0, 0, img.Width, img.Height, GraphicsUnit.Pixel);
g.Dispose();
img.Dispose();
// Save to a temp file:
string tempPath = Path.Combine(Path.GetTempPath(), "wallpaper.bmp");
copy.Save(tempPath, System.Drawing.Imaging.ImageFormat.Bmp);
RegistryKey key = Registry.CurrentUser.OpenSubKey( @"Control Panel\Desktop", true ) ;
key.SetValue(@"WallpaperStyle", 1.ToString( ) ) ;
key.SetValue(@"TileWallpaper", 0.ToString( ) ) ;
SystemParametersInfo( SPI_SETDESKWALLPAPER,
0,
tempPath,
SPIF_UPDATEINIFILE | SPIF_SENDWININICHANGE );
function Set-Wallpaper([string] $imgurl)
compile-CSharp $code
[test.Wallpaper]::SetWallpaper($imgurl)