How to remove the User picture from Login and Lock screen?

This method will hide the logon picture and the picture frame

1. Go to C:\Windows\System32\authui.dll and copy the file to your desktop twice.
   We modify the first one and keep the second as backup

2. Use Resource Hacker or similar tools and open the newly copied file on your desktop

3. Navigate to "UIFILE". There are four subfolders with different numeric names.
   12400, 12401, 12402 and 14000

4. Each subfolder will contain one single file called "1033".
   Open the first one and search for <ZoomableElement id="atom(PictureContainer)".
   Insert height="0" as shown below

   <ZoomableElement id="atom(PictureContainer)" height="0" layout="filllayout()">
   

   

5. This has to be done three times for the files under 12400, 12401 and 12402.
   Don't be confused: The CTRL+F search will jump automatically to the next file

6. If you have modified three files and searched for all occurrences you are finished.
   Just save the file and close Resource Hacker

7. Now go back to the original C:\Windows\System32\authui.dll and take ownership of that file and give yourself enough permissions to replace it with your modified file.

   <sup>- Properties » Security » Advanced » Owner » Edit
   - Properties » Security » Advanced » Permissions » Change permissions » Full control</sup>
   If you have taken enough permissions, rename the original file to authui.dll.bak

8. Finally copy your modified version to the system32 folder and restart your PC to take effect

_(optional)
Some people like to restore the original file permissions and original owner so you may want to write down those settings before you begin to change them. I do not know if that is necessary at all.

If you are lazy and trust me enough, you could also download this already modified authui.dll

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Warning

If you make a mistake somewhere while editing the file, you could get serious login problems. For example not seeing a password input box any more. From there you have to restore your backup file via a live CD system or following these instructions you could also use your Windows 7 install disc and repair the file.

Original source

From this extensive thread discussing many possible approaches:

create a small image (eg. 20x20 px) and create a 1% opacity (it seems you can't to go any lower) 1 pixel dot so the image is no longer transparent and it will work fine!

You can do this with, e.g. The GIMP or Paint.NET free image editing applications.