Windows 7 logon UI image files - How to locate and edit them?

Question

I want to change the color of my logon screen picture box - possibly along with other interface elements - in Windows 7.
The image I'm talking about is the glossy bluish box surrounding the selected user's profile picture, such as the one when you lock the screen and get a password prompt.

I would like to open the files in some image editor, convert them to grayscale to fit my logon background color and overwrite the old ones. Practically all I want to do is change the color, but there is no built-in way to do it (that I know of) and I guess it needs some file editing.
I realize there's an option to choose between 3 different colors for the "Switch User" button - unfortunately it doesn't change the picture box and password field arrow colors.

Q: Where might the image files be located, and how to bypass their protection (if applicable) so they're available for editing?

My system is Windows 7 Ultimate SP1 (64-bit), build 7601.

Solution

Custom 7 Authui.dll !

Additional Authui.dll resource info:

Windows 7 Logon Editing Guide

Custom Authui.dll sample:

Windows 7 Logon Screen Glass 32 Bit and 64 Bit

Edit logon GUI:

Logon WorkShop R2 (FreeWare)

Logon Workshop, Customize The Windows 7 Logon Screen.

Background Change:

GUI: Windows 7 Logon Background Changer

Command-line:

REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background" /v OEMBackground /t REG_DWORD /d 1 /f
md %windir%\System32\oobe\info\backgrounds\

Copy JPG file with size less than 256 kb in %windir%\System32\oobe\info\backgrounds folder and rename it to backgroundDefault.jpg

Comments

[STTR]

@Karan Thank you, my epic inattention, works flawlessly)

[Karan]

Yes, your answer works flawlessly, but it's not what the OP is asking for! :) This is what he wants to edit: "The image I'm talking about is the glossy bluish box surrounding the selected user's profile picture".

[STTR]

@Karan Update))

[rld.]

Great, the update seems to address my needs perfectly, it will be even easier if I only want to apply a color adjustment to the box. I will try this tomorrow, right now I don't have the time. Also if you could edit your answer to remove the unnecessary "change background" part, I'll be glad to accept it. I'm sure people can use simple programs like TweakLogon to change their background image, really, there's a ton of these questions on the web. I'd prefer the answer to only address editing the UI elements, as I couldn't find the question anywhere and answer may prove helpful for someone else.

[STTR]

@R3load May, need to change the background. This a full set)

[rld.]

@STTR You're right, after all I mentioned "other elements" I might want to change. It's perfect now with the Authui.dll tut at the top :) Tomorrow I will try to confirm if the tutorial works and immediately set your answer as "Accepted" if it does. Thank you for your time and effort!

[STTR]

@R3load. Custom Authui.dll sample found. Update.

[rld.]

I saw the Authui.dll guide - wow, now I'm sure I don't need to check anything. Think of it, I never did, as my question was about the file location. Sorry for stalling, I'm just a little sleepy. Accepting your answer, great job. Thanks a bunch.

[STTR]

@R3load. Logon WorkShop R2 (FreeWare) GUI software found.

[rld.]

@SSTR Looks great. I guess it was all about finding out about Authui.dll and it's a slide from there :) I wish I could upvote your question, but I've not enough reputation yet. I'll make sure to upvote after I get 15 (if it's still possible by then).

[rld.]

@SSTR You missed an image alt in the first image (picture guide) and the Logon WorkShop R2 (FreeWare) link points to a Softpedia download page, which immediately starts downloading a file. You might want to change it to point to the description page on Softpedia, users probably don't want to download the installer before they read about the software.

[STTR]

@R3load. Executed))

[rld.]

Got my 15 rep, +1 for you :)