Tuesday, May 14, 2013

Customising Windows Installation

In some cases - for example, where the only purpose of the PC is to run a specific software package - certain Windows features are customised with the provider's brand. Such features may include logon screen background, individual desktop backgrounds for each user and user account logon pictures (tile images). Therefore it may be useful to know where those are stored and how to update them. The following description is for Windows 7 and Windows Server 2008.

1. Windows logon screen background.

This is the easiest one. It should be copied to the following location: C:\Windows\system32\oobe\info\backgrounds\backgroundDefault.jpg. A registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background\OEMBackground should exist with a dword value of 00000001.

2. Desktop backgrounds (wallpaper) for each user

Check the following registry key: HKEY_CURRENT_USER\Control Panel\Desktop\Wallpaper. What I found was the following: C:\Users\Account_Name\AppData\Roaming\Microsoft\Windows\Themes\TranscodedWallpaper.jpg

Therefore, for each Account_Name the image has to be replaced with the desired one.

3. User Account logon pictures

This turned out to be trickier. There is a description on MSDN on how to do it manually [1]. Automating the task is not so obvious. Turns out, there is a function in the shell32.dll that sets a user login picture. It can be called easily from C# code by P/Invoke. In fact, the following is the full code of a console application that will update the user login picture.

using System;
using System.Runtime.InteropServices;

namespace UserPictureUpdater
    class Program
        [DllImport("shell32.dll", EntryPoint = "#262", CharSet = CharSet.Unicode, PreserveSig = false)]
        public static extern void SetUserTile(string username, int notneeded, string picturefilename);
        static void Main(string[] args)
            if (args.Length == 2)
                SetUserTile(args[0], 0, args[1]);

The application can run from command line

UserPictureUpdater Administrator adminnew.png

Or, in my case, I'm running it from PowerShell script the following way

Start-Process $command $params

Where $command is the full path, i.e. "C:\Folder\UserPictureUpdater.exe", and $params is the command line parameters, i.e. "Administrator adminnew.png".

Also, turns out someone figured out the way to do the whole thing in PowerShell [2]. But I was done with my approach by the time I found out.


About User Profiles
Setting the user tile image in Windows 7 and Server 2008 R2
by . Also posted on my website

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