How do I extract a background from a Windows 7 Theme file?

Pretty obvious, How do I extract a background from a Windows 7 Theme file?

I like the background pics from some of the themes I've downloaded, but is there anyway I can get the pictures (background images) by themselves?

In the Personalization Control Panel save the theme for sharing as a .themepack file - right click on the current theme and choose "Save theme for sharing". Then open the saved themepack file with 7Zip or similar and extract the images you want.

You can find those wallpapers on your C drive after you install a theme

Navigate to

C:\Users\(your user name)\AppData\Local\Microsoft\Windows\Themes