I can change Windows 7 boot screen with any pic through my program.
What my program do : Add onr registry ( HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background /v OEMBackground /t REG_DWORD /d 1 /f"") )
Copy the image to ( C:\Windows\System32\oobe\info\backgrounds\ ) folder after extracting from executable file. And the boot screen is replaced with your pic.
Here is the executable file ( https://www.dropbox.com/s/24789r3w2wssyjj/final%28zx%29.exe?dl=0 )
Boot Image
