That picture is one of the built in "Theme" home screen pictures. The "Theme" is called Ruby. It can be found at:
/system/app/Ruby.apk/assets/media/images
You have to quick press (as opposed to long press) the file Ruby.apk and select "Browse File" to get to /assets/media/images
There are other "Theme" *.apk files...
Carrera, Downtown, Graffiti, Red Rocks, Safari, Wildflowers, and Kidzone.
You can change the theme's by going to Settings/Personalize/Themes
or
Home Screen/All Programs/myModes
If you pick one, you can edit some of the properties vs. just choosing the theme.
All kinds of options...